Eta Geminorum

Eta Geminorum (η Geminorum, abbreviated Eta Gem, η Gem), formally named Propus , is a triple star system in the constellation of Gemini. It is a naked-eye variable star around 380 light years from the Sun.
Nomenclature.
"Eta Geminorum" is the star's Bayer designation. The traditional names "Tejat Prior", "Propus" (from the Greek, meaning forward foot) and "Praepes" and "Pish Pai" (from the Persian Pīshpāy, پیش‌پای, meaning foreleg). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Propus" for this star.
This star, along with γ Gem (Alhena), μ Gem (Tejat Posterior), ν Gem and ξ Gem (Alzirr) were "Al Han'ah", "the brand" (on the neck of the camel). They also were associated in "Al Nuḥātai", the dual form of "Al Nuḥāt", "a Camel's Hump".
In Chinese lunar mansion, Tejat Prior is the only member of the lunar mansion 钺 (Pinyin: "Yuè", Chinese 'Battle Axe').
Surroundings.
η Geminorum lies at the foot of the Castor side of Gemini, about two degrees west of μ Geminorum and two degrees southeast of the bright open cluster M35. Between the two stars are several faint areas of nebulosity. η Gem just to the west of the supernova remnant shell IC 443. Further east around μ Gem is the emission nebula S249. In between is the small faint emission nebula IC 444 around the 7th magnitude 12 Geminorum.
η Geminorum is 0.9 degree south of the ecliptic, so it can be occulted by the Moon and, rarely, by planets. The last occultation by a planet took place on July 27, 1910, by Venus, and the next to last on July 11, 1837, by Mercury.
Variability.
In 1865, Julius Schmidt first reported that η Geminorum was a variable star. The light variations were described by Schmidt and other observers as having long maxima of constant brightness, minima of greatly varying size and shape, and a period around 231 days. The star was classified as both a semiregular variable and an eclipsing variable. The eclipse period has been set at about eight years, corresponding to the orbit of an unseen companion. The eclipses have been questioned many times, but special observations are still being made at the times of predicted eclipses.
The semi-regular variations have been classified as type SRa, indicating relatively predictable periodicity with some variations in amplitude and light curve shape. These types of variable are considered to be very similar to Mira variables, but with smaller amplitudes. Many long-period variables show long secondary periods, typically ten times longer than the main period, but these changes have not been detected for η Geminorum. The main period has been refined to an average of 234 days.
System.
η Geminorum is a triple system, with the luminous class M star having a close companion known only from radial velocity variations, and a more distant companion resolved visually.
In 1881, Burnham observed that η Geminorum had a close companion (η Gem B). At that time the separation was measured to be 1.08". This has now increased to 1.65" and an orbit has been calculated to be 474 years long and rather eccentric. Little is known about the companion, although it is 6th magnitude. It is given a G0 spectral type and is assumed to be a giant on the basis of its brightness.
In 1902, William Wallace Campbell reported that η Geminorum A showed radial velocity variations. The assumption was that the star was a spectroscopic binary, although no period or other orbital parameters were determined. An orbit calculated in 1944 is essentially unchanged today, with a period of 2,983 days and an eccentricity of 0.53. Observations were made looking for sign of eclipses corresponding to the derived orbit, but the evidence was regarded as inconclusive. Due to the appearance of the spectrum, the spectroscopic companion is suspected to be a fainter M-class star.
Evolution.
The luminous main component of η Geminorum is an asymptotic giant branch star, a highly evolved cool luminous star that was originally on the main sequence. How the system contains 3 evolved stars with very different masses remains to be seen.
Namesakes.
USS Propus (AK-132) was a United States Navy Crater class cargo ship named after the star.


List of the star names in Draco

This is the list of the star names in the constellation Draco.


27 Canis Majoris

27 Canis Majoris is a binary star system in the northern constellation of Canis Major, located approximately 1,700 light years away from the Sun. It has the variable star designation EW Canis Majoris; "27 Canis Majoris" is the Flamsteed designation. This system is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of +4.65. It is moving away from the Earth with a heliocentric radial velocity of 16 km/s.
The pair of stars in this system were first resolved by W. S. Finsen in 1953, and the split has been widening since that time. The system has an orbital period of around 119 years with an eccentricity of 0.7 and a semimajor axis of . The magnitude 4.92 primary, designated component A, is a Be star with a stellar classification of B3 IIIpe. It is spinning rapidly with a projected rotational velocity of 290 km/s, compared to a critical velocity of 389 km/s. The star appears to be a Beta Cephei variable with a pulsation period of 0.0919 days and an amplitude of 0.0080 in magnitude.
The magnitude 5.39 secondary, component B, is classified as a Gamma Cassiopeiae type variable star. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.


52 Arietis

52 Arietis (abbreviated 52 Ari) is a triple star system in the northern constellation of Aries. "52 Arietis" is the Flamsteed designation. The combined apparent magnitude is +5.46, which is bright enough to be faintly visible to the naked eye. Based upon an annual parallax shift of 6.05 mas, the system is roughly distant from the Earth. The inner pair of this system consist of two nearly identical B-type main sequence stars, each with about five times the mass of the Sun. The tertiary component is a smaller star with 88% of the Sun's mass, and is a common proper motion companion.


Theta Crateris

Theta Crateris (θ Crateris) is a solitary star in the southern constellation of Crater. It is a photometric-standard star that is faintly visible to the naked eye with an apparent visual magnitude of 4.70. With an annual parallax shift of 11.63 mas as seen from Earth, it is located around 280 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.07 because of interstellar dust.
This is a B-type main sequence star with a stellar classification of B9.5 Vn, where the 'n' suffix indicates "nebulous" absorption lines due to rapid rotation. It is spinning with a projected rotational velocity of 212 km/s, giving the star an oblate shape with an equatorial bulge that is an estimated 7% larger than the polar radius. The star has 2.79 times the mass of the Sun and around 3.1 times the Sun's radius. With an age of about 117 million years, it is radiating 107 times the solar luminosity from its outer atmosphere at an effective temperature of 11,524 K.


Nu Lupi

The Bayer designation Nu Lupi (ν Lup / ν Lupi) is shared by two stars, in the constellation Lupus (constellation):


NGC 2998

NGC 2998 is a barred spiral galaxy located in the constellation Ursa Major. It is 195 million light-years (59.7 megaparsecs) away from the Earth. It is an intermediate spiral galaxy. Its stellar mass is about that of the Milky Way.
NGC 2998 is a member of the eponymous NGC 2998 group, a relatively dense galaxy group which also includes NGC 3002, NGC 3005, NGC 3006, NGC 3008 and a few others.


List of stars in Scorpius

This is the list of notable stars in the constellation Scorpius, sorted by decreasing brightness.


Rho Eridani

The Bayer designation ρ Eridani (Rho Eridani, ρ Eri) is shared by three stars in the constellation Eridanus that lie in a line:


Kepler-90

Kepler-90, also designated 2MASS J18574403+4918185, is a G-type main sequence star located about from Earth in the constellation of Draco. It is notable for possessing a planetary system that has the same number of observed planets as the Solar System.
On 14 December 2017, NASA and Google announced the discovery of an eighth planet, Kepler-90i, in the Kepler-90 system: the discovery was made using a new machine learning method developed by Google.
Nomenclature and history.
Prior to Kepler observation, Kepler-90 had the 2MASS catalogue number 2MASS J18574403+4918185. It has the designation of KIC 11442793 in the Kepler Input Catalog, and given the Kepler object of interest number of KOI-351 when it was found to have a transiting planet candidate.
The star's planetary system was discovered by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses involves detecting dips in brightness in stars. These dips in brightness can be interpreted as planets whose orbits move in front of their stars from the perspective of Earth. The name Kepler-90 derives directly from the fact that the star is the catalogued 90th star discovered by "Kepler" to have confirmed planets.
The designations "b", "c", "d", "e", "f", "g", "h", and "i" derive from the order of discovery. The designation of "b" is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of Kepler-90, there are eight planets discovered, so designations up to "i" are used.
Stellar characteristics.
Kepler-90 is a G-type star that is approximately 120% the mass and radius of the Sun. It has a surface temperature of 6080 K, and an estimated age of around 2 billion years. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 14. It is too dim to be seen with the naked eye, which typically can only see objects with a magnitude around 6 or less.
Planetary system.
Kepler-90 is notable for similarity of the configuration of its planetary system to that of the Solar System, in which rocky planets are nearer the star and gas giants farther away. The six inner planets range from super-Earths to mini-Neptunes in size. The two outermost planets are gas giants. The most distant known planet orbits its host star at about the same distance as Earth from the Sun.
Kepler-90 was used to test the "validation by multiplicity" confirmation method for Kepler planets. Six inner planets met all the requirements for confirmation. The penultimate planet showed transit-timing variations, indicating that it is a real planet as well.
The Kepler-90 system is the only eight-planet candidate system from Kepler, and the second to be discovered after the Solar System. It was also the only seven-planet candidate system from Kepler before the eighth was discovered in 2017. All of the eight known planet candidates orbit within about 1 AU from Kepler-90. A Hill stability test and an orbital integration of the system show that it is stable.
The five innermost exoplanets, Kepler-90b, c, i, d, and e may be tidally locked, meaning that one side of the exoplanets permanently faces the star in eternal daylight and the other side permanently faces away in eternal darkness.
A 2020 analysis of transit-timing variations of the two outermost planets Kepler-90g and h found best-fit masses of and , respectively. Given a transit-derived radius of , Kepler-90g was found to have an extremely low density of , unusually inflated for its mass and insolation. Several possible explanations for its apparently low density include a puffy planet with a dusty atmosphere or a smaller planet surrounded by a tilted wide ring system (albeit the latter option is less likely due to the lack of evidence for rings in transit data).
Near resonances.
Kepler-90's eight known planets all have periods that are close to being in integer ratio relationships with other planets' periods; that is, they are close to being in orbital resonance. The period ratios b:c, c:i and i:d are close to 4:5, 3:5 and 1:4, respectively (4: 4.977, 3: 4.97 and 1: 4.13) and d, e, f, g and h are close to a 2:3:4:7:11 period ratio (2: 3.078: 4.182: 7.051: 11.102; also 7: 11.021). f, g and h are also close to a 3:5:8 period ratio (3: 5.058: 7.964). Relevant to systems like this and that of Kepler-36, calculations suggest that the presence of an outer gas giant planet (as exemplified by g and h in this system) facilitates the formation of closely packed resonances among inner super-Earths. The semimajor axis of any additional nontransiting outer gas giant must be larger than 30 AU to keep from perturbing the observed planetary system out of the transiting plane.


NGC 6789

NGC 6789 is an irregular galaxy in the constellation Draco. It was discovered by Lewis Swift on Aug 30, 1883.


NGC 6522

NGC 6522 is a globular cluster in the constellation Sagittarius. It is apparent magnitude 8.3, and diameter 16.4 arc minutes, and class VI with stars 16th magnitude and dimmer. It was discovered by William Herschel on June 24, 1784. It is centered in a region of the sky known as Baade's Window.
NGC 6522 is possibly the oldest star cluster in the Milky Way, with an age of more than 12 billion years.


52 Herculis

52 Herculis is a triple star system in the northern constellation of Hercules. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.82. Based upon parallax measurements, the system is located 180 light years away from the Sun. It is moving closer to the Earth with a heliocentric radial velocity of −1.6 km/s.
The primary member, designated component A, is a magnetic chemically peculiar star with a stellar classification of A1VpSiSrCr, appearing as an A-type main-sequence star with abnormal abundances of silicon, strontium, and chromium. It is an alpha2 Canum Venaticorum variable that ranges in brightness from visual magnitude 4.78 down to 4.85 with a period of 3.8567 days. The star is about 525 million years old with a projected rotational velocity of 23 km/s. It has 2.2 times the mass of the Sun and 2.3 times the Sun's radius. The star is radiating 29.5 times the Sun's luminosity from its photosphere at an effective temperature of 8,840 K.
The remaining components form a binary star system with an orbital period of 56 years, an angular semimajor axis of , and an eccentricity of 0.13. They have an angular separation of from the primary. The total mass of the pair is and they have a combined visual magnitude of 8.85. The brighter member of this pair is a suspected K-type main-sequence star with a class of K0V.


CoRoT-2

CoRoT-2 is a yellow dwarf main sequence star a little cooler than the Sun. This star is located approximately 700 light-years away in the constellation of Aquila. The apparent magnitude of this star is 12, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night.
It has a true physical companion, 2MASS J19270636+0122577, with a spectral type of K9, as earlier hypothesized by Alonso et al. (2008), making CoRoT-2 a wide binary system with at least one planet.
Planetary system.
This star is home to exoplanet CoRoT-2b discovered by the CoRoT Mission spacecraft using the transit method. CoRoT-2b (formerly known as CoRoT-Exo-2b) is the second extrasolar planet to be detected by the French-led CoRoT mission, and orbits the star CoRoT-2 at a distance of 930 light years from Earth towards the constellation Aquila. Its discovery was announced on 20 December 2007. After its discovery via the transit method, its mass was confirmed via the radial velocity method.
The planet is a large hot Jupiter, about 1.43 times the radius of Jupiter and approximately 3.3 times as massive. Its huge size is due to the intense heating from its parent star, which causes the outer layers of its atmosphere to bloat. The extremely large radius of the planet indicates that CoRoT-2b is really hot, estimated to be around 1500 K, even hotter than would be expected given its location close to its parent star. This fact may be a sign of tidal heating due to interactions with another planet. At Jupiter-like distances its radius would roughly be the same as Jupiter.
The complete phase curve of this planet has been observed.
CoRoT-2b orbits its star approximately once every 1.7 days, and orbits the star in a prograde direction close to the star's equator. Its parent star is a G-type star, a bit cooler than the Sun but more active. It is located about 800 light-years from Earth.
It takes 125 minutes to transit its star.
As of August 2008, the CoRoT-2b spin-orbit angle (that is, the angle between the equator of the star and the plane of the planet orbit) was calculated by Bouchy "et al." by means of the Rossiter–McLaughlin effect with a value of +7.2 ± 4.5 degrees.


V Puppis

V Puppis (V Pup) is a star system in the constellation Puppis. Its apparent magnitude is 4.41. There is a binary star system at the center with a B1 dwarf orbiting a B3 subgiant star. They have an orbital period of 1.45 days and a distance of only 15 solar radii apart. However, the system moves back and forth, indicating that there is a massive object orbiting them with a period around 5.47 years. Based on the mass of the object, its lack of a visible spectrum, and circumstellar matter in the system with many heavy elements (as would be produced by a past supernova in the system), it is probably a black hole.
In addition to the main system, more distant components have been reported: B, at magnitude 11.5 and separation 6.2", C, at magnitude 13.2 and separation 18.9", D, at magnitude 9.88 and separation 39", and E, at magnitude 13 and separation from D of 10.4".


Delta Pictoris

Delta Pictoris (δ Pic) is a class B3III (blue giant) star in the constellation Pictor. Its apparent magnitude is 4.72 and it is approximately 1300 light years away based on parallax.
It is a β Lyrae variable, a type of eclipsing binary, which ranges in brightness from 4.90 to 4.65 magnitude with a period of 1.67 days.


NGC 3607

NGC 3607 is an unbarred spiral galaxy that forms part of the Leo II Group (NGC 3607 Group) of galaxies.
Orbital motions of the globular cluster system
imply an unusual poverty of dark matter:
perhaps 16±44% of the total mass within 5 effective radii.
Recent article shows that its central black hole has a mass of about
M• = (1.2 ± 0.4) × 108 M⊙


NGC 5582

NGC 5582 is an elliptical galaxy in the constellation Boötes. It was discovered by William Herschel on April 29, 1788.


V Sagittae

V Sagittae or V Sge is a cataclysmic variable binary star system in the constellation Sagitta that is expected to go nova and briefly become the most luminous point of light in the Milky Way and the brightest stars in our sky around the year 2083. The system is composed of a main sequence star of about 3.3 solar masses and a white dwarf of about 0.9 solar masses; the fact that the white dwarf is less massive than its companion is highly unusual, and V Sge is the only super soft X-ray source nonmagnetic cataclysmic variable found so far.
V Sge has brightened by a factor of 10 over the last century, and based on research reported in 2020, it is expected to continue to brighten and briefly become the brightest star in the night sky sometime around 2083, plus or minus about 11 years. Over the last few months and days the pair will coalesce and go nova, eventually becoming a red giant star.
The stars orbit each other about every 0.514 days, and eclipse each other each orbit. The pair is viewed in the late stages of their spiral in. Their orbital period currently decreases by 4.73 * 10−10 days per cycle, a rate which will accelerate.
Material from the larger star is accreting onto the white dwarf at an exponentially increasing rate, generating a huge stellar wind. The doubling time is about 89 years.


Phi Sagittarii

Phi Sagittarii (Phi Sgr, φ Sagittarii, φ Sgr) is a star in the southern constellation of Sagittarius. With an apparent visual magnitude of 3.17, it is the ninth-brightest star in the constellation and is readily visible to the naked eye. Parallax measurements place it at a distance of roughly from the Earth.
The stellar classification of this star has been rated at B8.5 III and B7 IV, with a luminosity class of III indicating it is a giant star, while a class of IV suggests it is still a subgiant star. Both represent stages in the evolution of a star after it has exhausted the hydrogen at its core. This energy is being radiated from the star's outer envelope at an effective temperature of 14,990 K, which produces the blue-white hue typical of B-type stars.
In the past, this star catalogued as a spectroscopic binary and a companion was apparently detected through lunar occultation. However, it is most likely a solitary star and any nearby stars are merely optical companions.
Name and etymology.
In the catalogue of stars in the "Calendarium" of Al Achsasi al Mouakket, this star was designated "Aoul al Sadirah", which was translated into Latin as "Prima τού al Sadirah", meaning "first returning ostrich".
In Chinese, (), meaning "Dipper", refers to an asterism consisting of φ Sagittarii, λ Sagittarii, μ Sagittarii, σ Sagittarii, τ Sagittarii and ζ Sagittarii. Consequently,the Chinese name for φ Sagittarii itself is (, .)
This star, together with γ Sgr, δ Sgr, ε Sgr, ζ Sgr, λ Sgr, σ Sgr and τ Sgr comprising the "Teapot" asterism. φ Sgr, σ Sgr, ζ Sgr, χ Sgr and τ Sgr were "Al Naʽām al Ṣādirah" (النعم السادرة), the Returning Ostriches. According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Naʽām al Ṣādirah" or "Namalsadirah" was originally the title for four stars: φ Sgr as "Namalsadirah I", τ Sgr as "Namalsadirah II", χ1 Sgr as "Namalsadirah III" and χ2 Sgr as "Namalsadirah IV" (except σ Sgr and ζ Sgr) .


20 Vulpeculae

20 Vulpeculae is single star located around 1,170 light years away in the northern constellation of Vulpecula. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.91. The object is moving closer to the Earth with a heliocentric radial velocity of −22 km/s.
This is a Be star with a stellar classification of B7 Ve. It is spinning rapidly with a projected rotational velocity of 236 km/s (compared to a critical velocity of 332 km/s) and has an estimated polar inclination of 71.1°. The star has four times the mass of the Sun and is radiating around 460 times the Sun's luminosity from its photosphere at an effective temperature of 12,050 K.


NGC 358

NGC 358 is a very small open cluster of four stars in the constellation of Cassiopeia. It was originally thought to be an unrelated Asterism, but two of the members were found to have a similar distance of roughly 1700 light years, although the other two do not have well-constrained distances, so its exact nature is uncertain.
The asterism was discovered on February 4, 1865 by the German-Danish astronomer Heinrich Louis d'Arrest.


NGC 2374

NGC 2374 is an open cluster in the Canis Major constellation.


Mu Velorum

Mu Velorum (μ Vel, μ Velorum) is a binary star system in the southern constellation Vela. The two stars orbit each other with a semi-major axis of 1.437 arcseconds and a period of 116.24 years. (Wulff-Dieter Heintz (1986) lists a period of 138 years with his orbital elements.) The pair have a combined apparent visual magnitude of 2.69, making the system readily visible to the naked eye. From parallax measurements, the distance to this system is estimated to be . The system is about 360 million years old.
The primary component is a giant star with an apparent magnitude of 2.7 and a stellar classification of G5 III. It is radiating about 107 times the luminosity of the Sun from an expanded atmosphere about 13 times the Sun's radius. The mass of this star is 3.3 times that of the Sun. In 1998, the Extreme Ultraviolet Explorer space telescope detected a strong flare that released an X-ray emission nearly equal to the output of the entire star. The quiescent X-ray luminosity of Mu Velorum A is about .
The fainter companion, Mu Velorum B, is a main sequence star with an apparent magnitude of 6.4 and an assigned stellar classification of G2V. However, this classification is suspect. Closer examination of the spectrum suggests the star may actually have a classification of F4V or F5V, which suggests a mass of about 1.5 times the mass of the Sun. Such stars typically do not show a marked level of magnetic activity.


NGC 5793

NGC 5793 is an active spiral galaxy located approximately 150 million light years away in the constellation Libra. It is classified as a seyfert galaxy and was discovered by Francis Leavenworth in 1886.
In 2014, the Hubble Space Telescope examined and photographed NGC 5793.
Seyfert galaxies such as NGC 5793 are known to house megamasers, these megamasers are capable of having a luminosity of thousands of times greater than the Sun.
Neutral hydrogen has been detected against the galactic nucleus. This means that NGC 5793 has an estimated HI cloud size of ≈15 pc and an estimated atomic gas density size of ≈200 cm -3.


TY Coronae Borealis

TY Coronae Borealis, also known as Ross 808, is a variable white dwarf star of the DAV (or ZZ Ceti) type in the constellation Corona Borealis. It has a surface temperature of 11,213 ± 130 K and a mass around 70% times that of the Sun, but only 1.1% of its diameter. It is around 100 light-years distant from Earth. It was confirmed as a variable star in 1976.


Theta Pictoris

Theta Pictoris (θ Pic) is a star in the Pictor constellation.
Theta Pictoris is a multiple star system: AB: 7.0, 7.5; PA 152°, separation 0.2" C: 7.0; PA 287°, separation 38".
The Theta Pictoris system consists of a total of 4 stars. Theta Pictoris C (HD 35859), an A2V star of about 6.77 magnitude, can be distinguished visually with a small telescope from the main system Theta Pictoris AB; its angular separation from AB is 38.3 arc seconds. Theta Pictoris AB, in turn, consists of a magnitude 6.76 A0V star and a magnitude 7.40 star separated by 0.287" with an orbital period of 123.2 years and eccentricity of 0.692. One of them is also an unresolved spectroscopic binary.
Tet Pic B or HD 35859, Hip 25298, SAO 233964


NGC 288

NGC 288 is a globular cluster in the constellation Sculptor. Its visual appearance was described by John Dreyer in 1888. It is located about 1.8° southeast of the galaxy NGC 253, 37′ north-northeast of the South Galactic Pole, 15′ south-southeast of a 9th magnitude star, and encompassed by a half-circular chain of stars that opens on its southwest side. It can be observed through binoculars. It is not very concentrated and has a well resolved, large 3′ dense core that is surrounded by a much more diffuse and irregular 9′ diameter ring. Peripheral members extend farther outward towards the south and especially southwest.


Kepler-23b

Kepler-23b is an exoplanet orbiting Kepler-23, located in the Cygnus constellation. The exoplanet was discovered with the Kepler space telescope in January 2012.
The planet is bigger than Earth, and its orbit is very close to its parent star. Orbital periods are 7.1 days and it presents a semi-major axis 0.099 AU.


89 Herculis

89 Herculis is a binary star system located about 4,700 light years away from the Sun in the northern constellation of Hercules. It is visible to the naked eye as a faint, fifth magnitude star. The system is moving closer to the Earth with a heliocentric radial velocity of −28.5 km/s.
This is a spectroscopic binary with the pair surrounded by a dusty disc. The system shows variable brightness and spectral line profiles. The companion has a very low mass and luminosity and orbits the primary in 288 days.
The primary component has a stellar classification of F2Ibe, and is among a rare class of post-asymptotic giant branch stars – low-mass stars in the last stages of their lives, highly inflated to appear as supergiants. It is classified as a semiregular variable star, subtype SRd, and ranges from magnitude 5.3 down to 5.5 over a period of around 68 days. The star has expanded to 71 times the Sun's radius and is radiating 8,350 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 6,550 K.


4 Cygni

4 Cygni is a binary star system in the northern constellation of Cygnus. It is a faintly visible to the naked eye with an apparent visual magnitude of 5.17. The distance to 4 Cygni, as determined from its annual parallax shift of , is about 560 light years.
This is single-lined spectroscopic binary with an orbital period of 35 days and an eccentricity of 0.45. The visible component is a B-type star with a stellar classification of , where the suffix notation indicates this is type of chemically peculiar star known as a silicon star. It displays an overabundance of iron in the visual spectrum, while the star appears helium-weak in the ultraviolet.
4 Cygni A is an Alpha2 Canum Venaticorum variable that varies by 0.02 magnitude over a period of 0.68674 days. The average quadratic field strength of the magnetic field is . With an age of 145 million years, it has four times the mass of the Sun and five times the Sun's radius. It radiates around 501 times the Sun's luminosity from its photosphere at an effective temperature of 12,190 K.


Phi Orionis

The Bayer designation Phi Orionis (φ Ori, φ Orionis) is shared by two star systems in the constellation Orion.
The two stars are separated by approximately 0.71° in the sky.
Etymology.
Both of φ Ori and λ Ori were Al Haḳʽah, "a White Spot".
The similar composition were found in Chinese astronomy, known as (), meaning "Turtle Beak (asterism)", Consequently, both of φ Ori themselves is known as ( .) (for φ1Ori) and ( .) (for φ2Ori)


V520 Persei

V520 Persei is a blue supergiant member of NGC 869, one of the Perseus Double Cluster open clusters. It is an irregular variable star.
V520 Persei is the brightest member of the Double Cluster at magnitude 6.55. Two brighter stars in the same field are foreground objects. 7 Persei, sometimes considered to be the actual star χ Persei, is a yellow giant star, and HD 14443 is a white supergiant. Several other early B supergiants in NGC 869 are the most luminous members of the cluster, while NGC 884 contains several red supergiants.
The Washington Double Star Catalog lists V520 Per as a double star about 15" from a 13th magnitude A0 companion which is another cluster member. There are dozens of other stars within an arc-minute, including several brighter than 10th magnitude and two 15th magnitude stars closer than the listed companion. The Catalogue of Components of Double and Multiple Stars also lists a single companion, but it is an 11th magnitude star 29" away.
The Hipparcos parallax is negative with a large margin of error, so does not constrain the distance except that it is clearly large However, V520 Per is a well-defined member of NGC 869 by location, proper motion, photometry, and spectroscopy, which places it at the same distance of around 7,000 light years.
The type of variability is listed in the General Catalogue of Variable Stars as IA, indicating it is poorly studied with no clear period. The visual range is 6.52 - 6.67. Statistical analysis of Hipparcos photometry suggests a possible period of 1.6 days, but the type variability is not clearly defined.
V520 Persei is a supergiant with a spectral class of B3. It also shows some emission lines in its spectrum. It has exhausted its core hydrogen and expanded into a more luminous star fusing hydrogen in a shell or helium in its core. It is over 100,000 times more luminous than the sun, although only thirty times its mass. Much of the luminosity arises from ultraviolet radiation created by the temperature of over 20,000 K.
V520 Per has been identified as one of Flamsteed's "missing stars", catalogue numbers created by Flamsteed but not actually associated with a current star in that constellation. It is described as being 61 Andromedae, although it is well outside the boundary of Andromeda and Flamsteed catalogued other nearby stars in Perseus, for example 7 Persei for χ Per itself.


NGC 3402

NGC 3402, also known as NGC 3411, is an elliptical galaxy in the constellation Hydra. The object was discovered on March 25, 1786 by German-British astronomer William Herschel. NGC 3402 is the largest galaxy in the eponymous NGC 3402 cluster.


NGC 2257

NGC 2257 is a globular cluster that lies on the outskirts of the Large Magellanic Cloud (LMC).


Omicron Tauri

ο Tauri, Latinized as Omicron Tauri, is a binary star system in the constellation Taurus, near the constellation border with Cetus. It has a yellow hue and is visible to the naked eye with an apparent visual magnitude of 3.61. It is approximately 191 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20 km/s. This system has the Flamsteed designation 1 Tauri; Omicron Tauri is the Bayer designation.
This is a single-lined spectroscopic binary system with the two components orbiting each other over a period of with an eccentricity of 0.263. The visible component is an aging G-type giant with a stellar classification of G6 III. This star has three times the mass of the Sun and eighteen times the Sun's radius. Based on the latter, interferometry-measured radius, it is rotating once every 533 days. It is radiating 149 times the luminosity of the Sun from its photosphere at an effective temperature of 5,180 K.


NGC 334

NGC 334 is a barred spiral galaxy in the constellation Sculptor. It was discovered on September 25, 1834 by John Herschel. It was described by Dreyer as "very faint, small, round, gradually a little brighter middle, 2 stars of 11th magnitude to south."


50 Cancri

50 Cancri is a single star in the zodiac constellation of Cancer, located 183 light years away from the Sun. It has the Bayer designation A2 Cancri; "50 Cancri" is the Flamsteed designation. It is faintly visible to the naked eye as a white-hued star with an apparent visual magnitude of 5.89. The star is moving away from the Earth with a heliocentric radial velocity of 23 km/s, having come to within some 1.2 million years ago.
This is a chemically peculiar A-type main-sequence star with a stellar classification of A1 Vp. It is a Lambda Boötis star displaying strongly-depleted iron peak and alpha process elements, but otherwise relatively normal solar abundances. The star shows no variability down to a detection limit of 1.6 millimagnitudes. It is 264 million years old with a relatively low projected rotational velocity of 18 km/s. 50 Cancri has 2.1 times the mass of the Sun and is radiating 11 times the Sun's luminosity from its photosphere at an effective temperature of 8,340 K.
50 Cancri has an infrared excess, which most likely indicates a debris disk in orbit around the host star. A blackbody model of the emission shows a two component fit, with the warm section having a temperature of at a radius of from the star, and a cool component at with a separation of .


Pyxis globular cluster

The Pyxis globular cluster is a globular cluster in the constellation Pyxis. It lies around 130,000 light-years distant from earth and around 133,000 light-years distant from the centre of the Milky Way—a distance not previously thought to contain globular clusters. It is around 13.3 ± 1.3 billion years old. Discovered in 1995 by astronomer Ronald Weinberger while he was looking for planetary nebulae, it is in the Galactic halo. Irwin and colleagues noted that it appears to lie on the same plane as the Large Magellanic Cloud and raised the possibility that it might be an escaped object from that galaxy.


Gamma Circini

Gamma Circini, Latinized from γ Circini, is a star system in the constellation Circinus. It was noted as a double star by Herschel in 1835, who estimated the separation as 1 arc second. It is visible to the naked eye with an apparent visual magnitude of 4.51. Based upon an annual parallax shift of 7.27 mas, it is about 450 light years away.
This is a wide binary star system and may even be a triple star. The two visible components orbit each other with a preliminary estimated period of 258 years and a large eccentricity of 0.931. As of 2014, the visible components have an angular separation of 0.80 arc seconds on a position angle of 359°.
The primary star, component A, is a B-type subgiant star with a stellar classification of B5 IV. Based upon isochrone curve fitting it is hypothesized to be a pair of matching B5 stars, and is a Be variable with an uncertain maximum. It has an effective temperature of 15,135 K and an estimated mass six times that of the Sun. The companion, component B, is an F-type main sequence star with a stellar classification of F8 V. It has an effective temperature of 4,786 K.


KKR 25

KKR 25 is an irregular galaxy in the constellation of Draco. It is about 6.4 million light years (1.95 megaparsecs) away from the Earth. KKR 25 is located outside the Local Group but the Local group is the nearest galaxy group with the M81 Group being the second nearest.


NGC 5557

NGC 5557 is an elliptical galaxy in the constellation Boötes. It was discovered by William Herschel on May 1, 1785. The distance to NGC 5557 is not well known, but it is estimated to be about 127 million light-years (38.8 megaparsecs) away.
NGC 5557 is quite massive, with a K-band absolute magnitude of −24.8, and is a slow rotator, which suggests it gained mass through dry mergers (galaxy mergers involving galaxies significant amounts of gas). However, it has a faint tidal tail to its east, as well as a more complex structure to the west. This structure, if found to be connected to NGC 5557, would one of the largest around a galaxy, spanning about 1.1 million light-years (350,000 parsecs). This filamentary structure suggests that NGC 5557 may have formed from a more gas-rich galaxy merger a couple billion years ago. This implies that the galaxy merger would need to have a low impact parameter.
NGC 5557 is part of a galaxy group, and is the largest such galaxy in the group by far. Surrounding the galaxy near the eastern filament are several small bluish objects, which are possibly tidal dwarf galaxies.


Alphard

Alphard , designated Alpha Hydrae (α Hydrae, abbreviated Alpha Hya, α Hya), is the brightest star in the constellation of Hydra. It is a single giant star, cooler than the sun but larger and more luminous. It is about 177 light years away.
Nomenclature.
"α Hydrae" (Latinised to "Alpha Hydrae") is the star's Bayer designation.
The traditional name "Alphard" is from the Arabic الفرد ("al-fard"), "the individual", there being no other bright stars near it. It was also known as the "backbone of the Serpent" to the Arabs. In the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", it was designated "Soheil al Fard", which was translated into Latin as "Soheil Solitarius", meaning "the bright solitary one". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Alphard" for this star. It is now so entered in the IAU Catalog of Star Names.
The European astronomer Tycho Brahe dubbed it "Cor Hydræ", Latin for 'the heart of Hydra'.
In Chinese, (), meaning "Star", refers to an asterism consisting of Alphard, τ1 Hydrae, τ2 Hydrae, ι Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. Consequently, Alphard itself is known as (), "the First Star of Star". In ancient China it formed part of an asterism called the "red bird".
Properties.
Alphard has three times the mass of the Sun. Its estimated age is 420 million years and it has evolved away from the main sequence to become a giant star with a spectral classification of K3 and luminosity class between II and III. The angular diameter has been measured using long-baseline interferometry, yielding a value of milliarcseconds, only beaten in it by Betelgeuse and R Doradus. It has expanded to 50 times the radius of the Sun.
Alphard's spectrum shows a mild excess of barium, an element that is normally produced by the s-process of nucleosynthesis. Typically a barium star belongs to a binary system and the anomalies in abundances are explained by mass transfer from a companion white dwarf star.
Precise radial velocity measurements have shown variations in the stellar radial velocities and spectral line profiles. The oscillations are multi-periodic with periods from several hours up to several days. The short-term oscillations were assumed to be a result of stellar pulsations, similar to the solar ones. A correlation between the variations in the asymmetry of the spectral line profile and the radial velocity has also been found. The multi-periodic oscillations make HD 81797 (Alphard) an object of interest for asteroseismologic investigations.
Modern legacy.
Alphard appears on the flag of Brazil, symbolising the state of Mato Grosso do Sul.
The Toyota Alphard is a minivan named after this star.
The character Roy Alphard from "" is named after this star.


Eta Leonis

Eta Leonis (η Leo, η Leonis) is a fourth-magnitude star in the constellation Leo, about away.
Properties.
Eta Leonis is a white supergiant with the stellar classification A0Ib. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Though its apparent magnitude is 3.5, making it a relatively dim star to the naked eye, it is nearly 20,000 times more luminous than the Sun, with an absolute magnitude of -5.60. The Hipparcos astrometric data has estimated the distance of Eta Leonis to be roughly 390 parsecs from Earth, or 1,270 light years away.
Eta Leonis is apparently a multiple star system, but the number of components and their separation is uncertain.


4 Canum Venaticorum

4 Canum Venaticorum is a binary star system in the northern constellation of Canes Venatici, located around 425 light years away. It has the variable star designation AI Canum Venaticorum; "4 Canum Venaticorum" is its Flamsteed designation. Its brightness varies from magnitude +5.89 to +6.15 with a period of 2.8 hours, which places it around the lower limit of visibility to the naked eye. This was found to be a binary by Schmid et al. in 2014, based on periodic, non-sinusoidal changes in its radial velocity. It is a single-lined spectroscopic binary with an orbital period of 124.4 days and an eccentricity of 0.31.
The primary component is an evolved F-type star with a stellar classification of F3 IV or F0 III, matching a subgiant or giant star, respectively. It is a variable of the Delta Scuti class, displaying both radial and non-radial pulsations. The variable nature of this star was discovered by D. H. P. Jones and C. Margaret Haslam in 1966 at the suggestion of Olin J. Eggen, and it has become one of the best studied stars in its class. The radial pulsations have shown little if any variations between 1974 and 2012. However, the non-radial pulsations vary continuously in frequency over periods spanning decades. It is spinning rapidly with a rotation of at least one third of its critical velocity.


20 Cygni

20 Cygni is a single, orange-hued star in the northern constellation of Cygnus. It is a faint star but is visible to the naked eye with an apparent visual magnitude of 5.03. The distance to 20 Cygni can be estimated from its annual parallax shift of , which yields a range of 202 light years. It is moving closer to the Earth with a heliocentric radial velocity of .
This is an aging red giant star with a stellar classification of , a star that has used up its core hydrogen and is expanding. The suffix notation indicates there are unusually strong lines of cyanogen in the spectrum. 20 Cyg is listed as one of the least variable stars in the Hipparcos catalogue, changing its brightness by no more than 0.01 magnitude. It has 1.28 times the mass of the Sun and has expanded to 13 times the Sun's radius. The star is radiating 57.5 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,337 K.


NGC 7250

NGC 7250 is an irregular galaxy located in the Lacerta constellation. It is a blue-colored galaxy with bright bursts of star formation: its star forming rate is more than an order of magnitude greater than that of the Milky Way.
In 2013, a type Ia supernova was detected within the galaxy, and was designated SN 2013dy. It was detected about 2.4 hours after the explosion, making it the earliest known detection of a supernova at the time.
The brighter star located in front of the galaxy is named TYC 3203-450-1, and is barely studied. It is about a million times closer to Earth than it the galaxy itself.


Adhil

The name Adhil has been applied to a number of stars, especially in the constellation of Andromeda. It is the name approved by the International Astronomical Union for Xi Andromedae.
Origin.
"Adhil" was originally applied to the description of Ptolemy's 21st and 22nd of Andromeda in his star catalogue in Latin translated version of "Almagest".
Renaissance times.
However Bayer gave "Adhil" for 60/b And in his prominent work "Uranometria" in 1603, and Bode followed Bayer in his great star atlas "Uranographia" in 1801.
Recent times.
"Adhil" is applied to Xi Andromedae from Manitius' identification of Ptolemy's 21st of Andromeda.


List of stars in Canes Venatici

This is the list of notable stars in the constellation Canes Venatici, sorted by decreasing brightness.


GZ Velorum

GZ Velorum is a single, orange-hued star in the southern constellation of Vela. It is a faint star but visible to the naked eye, having an apparent visual magnitude of 4.58. The star is located around 1,300 light years from Earth, as determined from its annual parallax shift of . It is moving further away with a heliocentric radial velocity of +13 km/s.
This is a bright giant star with a stellar classification of K2.5 II. It is a slow irregular variable of type LC with a frequency of 0.16585 cycles per day. In the R (red) band, the magnitude of the star ranges from 3.43 down to 3.81. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of GZ Vel, this yields a physical size of about 140 times the radius of the Sun.
GZ Vel is 30 million years old with 9 times the mass of the Sun. It is radiating 9,241 times the Sun's luminosity from its photosphere at an effective temperature of 4,140 K.
References.
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NGC 202

NGC 202 is a lenticular galaxy located in the constellation Pisces. It was discovered on November 17, 1876 by Édouard Stephan.


Perseus molecular cloud

The Perseus molecular cloud (Per MCld) is a nearby (~1000 ly) giant molecular cloud in the constellation of Perseus and contains over 10,000 solar masses of gas and dust covering an area of 6 by 2 degrees. Unlike the Orion molecular cloud it is almost invisible apart from two clusters, IC 348 and NGC 1333, where low-mass stars are formed. It is very bright at mid and far-infrared wavelengths and in the submillimeter originating in dust heated by the newly formed low-mass stars.
It shows a curious ring structure in maps made by the IRAS and MSX satellites and the Spitzer Space Telescope and has been detected by the COSMOSOMAS at microwave frequencies as a source of anomalous "spinning dust" emission.


Nu Lyrae

The Bayer designation ν Lyrae is shared by two stars in the constellation Lyra:


BQ Octantis

BQ Octantis (BQ Oct) is a variable star in the constellation Octans. It is an S-type star with an apparent magnitude of 6.82. It lies less than a quarter degree from the South Celestial Pole (SCP), making it the closest star to the SCP brighter than magnitude 10. While it is much nearer than Sigma Octantis (the star commonly used as the south pole star), it is too dim to the naked eye to use as a visual reference under typical skies.
BQ Octantis is a red giant on the asymptotic giant branch. Its spectrum has been classified as M3III or M4III. The spectrum shows abnormal abundances of s-process elements and particularly ZrO, so it is classified as an S star. These stars have dredged up fusion products from the interior, especially carbon. They have reached approximately equal levels of carbon and oxygen in their atmospheres, which causes dramatic changes to the atmospheric chemistry which are visible in the spectrum. As an S star, its spectrum is classified as S5,1, with S5 approximately equivalent to the temperature of an M5 giant and the 1 indicating that the ZrO bands are relatively weak.
BQ Octantis is a variable star. An amplitude of 0.05 magnitudes about an apparent magnitude of 6.82 has been derived from Hipparcos satellite photometry. The same photometry found a possible period of but this was very uncertain and no variability type could be determined. It is listed in the General Catalogue of Variable Stars as a possible slow irregular variable. It was classified as a variable star in 1977, on the basis of a 1960 study.


NGC 270

NGC 270 is a lenticular galaxy in the constellation Cetus. It was discovered on December 10, 1798 by William Herschel.


K Velorum

The Bayer designations k Velorum and K Velorum are distinct. Due to , both designations link here. For the star


HIP 57274

HIP 57274 is a star in the northern circumpolar constellation of Ursa Major with a system of three planets. It is invisible to the naked eye, having an apparent visual magnitude of 8.96. The distance to this system is 84.4 light years based on stellar parallax, and it is drifting further away with a radial velocity of +30 km/s. The star has a relatively high rate of proper motion, traversing the celestial sphere at the rate of .
This is an ordinary K-type main-sequence star with a stellar classification of K5V. It appears to be older than the Sun with an age of roughly eight billion years and is spinning slowly with a projected rotational velocity of under 1 km/s. The star has 73% of the mass of the Sun and 68% of the Sun's radius. The abundance of elements heavier than helium is about the same or slightly higher than in the Sun. The star is radiating just 19% of the luminosity of the Sun from its photosphere at an effective temperature of 4,640 K.
Planetary system.
The three exoplanets orbiting HIP 57274 were discovered by the radial velocity method in 2011, all of them having mass significantly greater than the Earth. A 2014 search for planetary transits was unsuccessful. The planetary orbits are possibly highly variable, being strongly affected by mean motion resonances. The most stable region for a hypothetical super-earth within the star's habitable zone would be an orbit inside 0.37– from the host star.


Zeta Ursae Minoris

Zeta Ursae Minoris, which is Latinized from ζ Ursae Minoris, is a single star in the northern circumpolar constellation of Ursa Minor, forming the northernmost part of the bowl in this "little dipper" asterism. The star has a white hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.28. It is located at a distance of approximately 369 light years from the Sun based on parallax, but is drifting further closer with a radial velocity of about −13 km/s.
The stellar classification of Zeta UMi is A3Vn, a notation that indicates this is an A-type main-sequence star with broad "nebulous" absorption lines in its spectrum due to rapid rotation. Based on photometric data, some light variability was suspected by R. A. Baker in 1926, and it may be a Delta Scuti variable. The star is spinning with a projected rotational velocity of 210 km/s, which is creating an equatorial bulge that is estimated to be 10% larger than the polar radius.
Zeta Ursae Minoris is about 180 million years old with 6.15 times the radius of the Sun. It is radiating 227 times the luminosity of the Sun from its photosphere at an effective temperature of 8,720 K. This anomalously high temperature and an absolute magnitude of −0.98 may indicate it is on the verge of evolving into a giant star. An infrared excess has been detected from an orbiting circumstellar disk. A black body fit to the data yields a mean dust temperature of 160 K and an orbital radius of .
In some Arabic star charts it is listed as أخفى الفرقدين "ʼakhfā al-farqadayn", meaning "the dimmer of the two calves", and paired with η Ursae Minoris as "ʼanwar al-farqadayn", "the brighter of the two calves". The names may originally refer to a pair of Ibexes, and are more properly applied to γ UMi and β UMi respectively, the brighter two stars in the rectangle of Ursa Minor.


HD 76653

HD 76653 is a single star in the southern constellation Vela. It is faintly visible to the naked eye with an apparent visual magnitude of +5.71. Based upon an annual parallax shift of 41.22 mas as seen from Earth, it is located 79 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −6 km/s. It is a probable (96% chance) co-moving companion of the nearby Delta Velorum; the two have an estimated physical separation of with similar proper motions. Both are likely members of the Ursa Major association.
This is an F-type main-sequence star with a stellar classification of F6 V. It is larger than the Sun, with 1.22 times the mass of the Sun and 1.35 times the Sun's luminosity. The star is radiating 2.72 times the Sun's luminosity from its photosphere at an effective temperature of about 6,296 K. Pace (2013) estimates HD 76653 to be 770 million years old, while Fuhrmann and Chini (2012) date it to an age of around two billion years. However, is an X-ray source with a luminosity of , which is unusually high for the older age estimate. The metallicity is near solar and it is spinning with a projected rotational velocity of 10.3 km/s.
HD 76653 displays an infrared excess that suggests the presence of an orbiting debris disk. This excess was detected with the Spitzer Space Telescope both by the IRS instrument at 30−34 μm and weakly by MIPS at 70 μm. The dust has a temperature of about 73−77 K and is orbiting at a mean distance of 16−18 AU from the host star.


Epsilon Normae

Epsilon Normae, Latinised from ε Normae, is a blue-white hued triple star system in the southern constellation of Norma. It has an apparent visual magnitude of 4.47, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 6.15 mas as seen from Earth, the system is located around 530 light years distant from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.21 due to interstellar dust.
The inner pair form a double-lined spectroscopic binary system with an orbital period of 3.26 days and an eccentricity of 0.13. Both stars appear to be similar B-type main-sequence stars with stellar classifications of B4 V. The third component has an angular separation of 22.8 arc seconds from the inner pair, and most likely is a smaller B-type main sequence star of spectral type B9V. The system is relatively young, with an estimated age of around 50 million years.


NGC 507

NGC 507, also known as Arp 229, CGCG 502-67, MCG 5-4-44, PGC 5098, UGC 938, and V V 207, is a lenticular galaxy in the constellation Pisces. It was described as being "very faint", "pretty large", "round", "brighter in the middle", and "south of NGC 508" by John Dreyer in the New General Catalogue. The two galaxies (NGC 507 and NGC 508) are a part of the Atlas of Peculiar Galaxies, where NGC 507 is described as "Circular or near circular rings of small density difference."
It was discovered by William Herschel on September 12, 1784.


V830 Tauri b

V830 Tauri b is an exoplanet orbiting around the young T Tauri star V830 Tauri, about away from Earth in the constellation of Taurus. The exoplanet has a young age of only about 2 million years.
Characteristics.
Orbit and mass.
V830 Tauri b orbits its parent star every 4.93 days at a distance of 0.057 AU from its parent star. This is about 7x closer to the host star than the planet Mercury is to the Sun. Its mass is about 70% that of Jupiter, and, because it is orbiting very close to its parent star, it is classified as a hot Jupiter.
Host star and age.
The host star, V830 Tauri, is a T Tauri star that is the same mass of the Sun, but twice the radius. It has a surface temperature of 4250 ± 50 K. In comparison, the Sun has a surface temperature of 5778 K. The star's age is estimated to be about 2 million years old, which makes it a very young star. For comparison, the Sun is 4.6 billion years old. The star has not yet fully contracted to become a main sequence star, which ties in with its bloated radius but similar mass to the Sun. Given its mass, it will likely be on the main sequence portion of its lifetime for about 10 billion years, much like the Sun.
Discovery.
Significance.
Previously, before the discovery of V830 Tauri b (and a slightly older planet named K2-33b, with an age around 5-10 million years), TW Hya b was discovered and disproven and PTFO 8-8695 b / CVSO 30 b was discovered with an age equally young and an orbit even closer. The yet unconfirmed objects are pending confirmation. The discovery of V830 Tauri b, K2-33b and PTFO 8-8695 b / CVSO 30 b suggests that the formation and migration of close-in giant planets can occur on a timescale of only a few million years. The new discoveries support planet-disc interactions as the most likely mechanism for efficiently producing young hot Jupiters.


24 Scorpii

24 Scorpii is a star that was originally placed by John Flamsteed within the constellation of Scorpius but in now placed within the southeastern constellation of Ophiuchus. It is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 4.91. Based on the trigonometric parallax published in Gaia Data Release 2, the star lies approximately 121 parsecs or 390 light years away. It is positioned near the ecliptic and thus is subject to lunar occultations.
This object is a luminous giant star that is classified by spectral and luminosity class as G7.5II or G7.5II-IIICN1Ba0.5. 24 Sco is associated with the faint reflection nebulae RfN VDB 109 or GN 16.36.7, but may just lie along the same line of sight. It is a very mild Barium star, but the enhanced barium lines in the spectrum may be a simple luminosity effect rather than a true abundance anomaly. It is a probable horizontal branch star, fusing helium in its core, with just a 13% likelihood that it is still on the red giant branch. The star has 2.51 times the mass of the Sun and has expanded to 22 times the Sun's radius. It is radiating 208 times the Sun's luminosity from its photosphere at an effective temperature of 4,667 K.


HD 240237 b

HD 240237 b is a super-Jupiter exoplanet orbiting the K-type giant star HD 240237 about 4,900 light-years (1,500 parsecs, or nearly km) away from Earth in the constellation Cassiopeia. It orbits outside of the habitable zone of its star at a distance of 1.9 AU. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. The planet has a mildly eccentric orbit.
Characteristics.
Mass, radius and temperature.
HD 240237 b is a "super-Jupiter", an exoplanet that has a radius and mass larger than that of the gas giants Jupiter and Saturn. It has a temperature of , around that of the surface temperature of Venus. It has an estimated mass of around 5.3 and a potential radius of around 9% larger than Jupiter (1.11 , or 12.2 ) based on its mass, since it is more massive than the jovian planet.
Host star.
The planet orbits a (K-type) giant star named HD 240237. It has exhausted the hydrogen supply in its core and is currently fusing helium. The star has a mass of 1.69 and a radius of around 32 . It has a surface temperature of 4361K and is likely 2 billion years old based on its mass and evolution. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 8.19. Therefore, HD 240237 is too dim to be seen with the naked eye.
Orbit.
HD 240237 b orbits its star with nearly 331 times the Sun's luminosity (331 ) every 746 days at a distance of 1.9 AU (compared to Mars' orbital distance from the Sun, which is 1.52 AU). It has a mildly eccentric orbit, with an eccentricity of 0.4.
Discovery.
The planet was detected through Doppler spectroscopy, the method of observing exoplanets through the measurement of radial velocities of a star. If there is a wobble, it could mean that there is a possible planetary companion orbiting it.
Observations were taken with the Hobby-Eberly Telescope equipped with the High-Resolution Spectrograph in a queue-scheduled mode. From July 2004 to October 2009, 40 epochs were measured, with SNR values ranging from 161–450. These observations eventually led the team to conclude that there was in fact a planetary companion orbiting around HD 240237, and they estimated its parameters to be a mass of 5.3 times that of Jupiter, an orbital period of 746 days, an eccentricity of 0.4, and a semi-major axis of 1.9 AU. The discovery, along with 2 other exoplanets, were announced on October 9, 2011.


Omega2 Scorpii

ω2 Scorpii, Latinised as Omega2 Scorpii, is a suspected variable star in the zodiac constellation of Scorpius. A component of the visual double star ω Scorpii, it is bright enough to be seen with the naked eye having an apparent visual magnitude of +4.320. The distance to this star, as determined using parallax measurements, is around 291 light years. The visual magnitude of this star is reduced by 0.38 because of extinction from interstellar dust.
It is 0.05 degree north of the ecliptic, so can be occulted by the moon and planets.
This is a G-type giant star with a stellar classification of G6/8III. With an estimated age of 282 million years, it is an evolved, thin disk star that is currently on the red horizontal branch. The interferometry-measured angular diameter of this star is , which, at its estimated distance, equates to a physical radius of nearly 16 times the radius of the Sun. It has 3.27 times the mass of the Sun, and radiates 141 times the Sun's luminosity The effective temperature of the star's outer atmosphere is 5,363 K.
Names.
In the Cook Islands, a traditional story is told of twins who flee their parents into the sky and become the pair of stars Omega2 and Omega1 Scorpii. The girl, who is called Piri-ere-ua "Inseparable", keeps tight hold of her brother, who is not named. (The IAU used a version of this story from Tahiti to name Mu2 Scorpii.)
References.
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UU Aurigae

UU Aurigae is a carbon star in the constellation Auriga. It is approximately from Earth.
Description.
UU Aurigae is a carbon-rich asymptotic giant branch star. The spectral type listed in the General Catalogue of Variable Stars (GCVS) is C5,3-C7,4(N3). The N3 refers back to an older type of classification where carbon stars were given spectral types of N or R, although the numeric index was correlated more with the strength of the carbon chemistry rather than temperature. The C5 to C7 indicates various classifications using the newer Morgan-Keenan system where the numeric index corresponds better to the temperature of the star. C5 - C7 types are approximately equivalent to early-M stars. The second numeric index, 3 or 4 for UU Aurigae indicates the strength of the Swan bands in the spectrum, on a scale of 1 to 5. Using the more modern revised Morgan-Keenan scheme, a spectral type of C-N5- C2 6- has been published, with the C-N5 indicating an N-type carbon star with a temperature index of 5-, and a Swan band strength of 6- on a scale of 1 to 8.
UU Aurigae is classified as a semiregular variable of type SRb, indicating it is a giant star with poorly-defined variations. Its brightness varies from magnitude +4.9 to +7.0 in visual apparent magnitude. The period is given in the GCVS as 441 days, but there is also a strong variation with a period of 235 days. Using British Astronomical Association observations from 1971 to 1998, the periods are calculated as 439.4 and 233.1 days.
The angular diameter of UU Aurigae has been measured at 12.07 ± 0.22 mas using very-long-baseline interferometry (VLBI). Around the star is a shell of dust made up largely of amorphous carbon and silicon carbide (SiC), with the SiC appearing at three times the star's radius and the amorphous carbon at nine times its radius. Further out is a carbon-rich shell at 300 stellar radii and two oxygen-rich shells even further away. UU Aurigae also has a bow shock 0.14 parsecs wide, created by its motion through the interstellar medium.


Mu Persei

Mu Persei (Mu Per, μ Persei, μ Per) is a binary star in the constellation of Perseus, with an apparent magnitude of +4.16. The primary component is a yellow G-type supergiant. It is approximately 900 light years from Earth. With an effective temperature of about 5400 kelvins and a radius of 53 solar radii, this star has the luminosity of about 2030 times that of the Sun. Mu Persei is a spectroscopic binary with an orbital period of 284 days and an eccentricity of about 0.06.
Mu Persei is moving through the Galaxy at a speed of 35.6 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,900 and 32,400 light years from the center of the Galaxy.
Mu Persei came closest to the Sun 5.6 million years ago when it had brightened to magnitude 3.25 from a distance of 600 light years.
Naming.
In Chinese, (), meaning "Celestial Boat", refers to an asterism consisting of μ Persei, η Persei, γ Persei, α Persei, ψ Persei, δ Persei, 48 Persei and HD 27084. Consequently, μ Persei itself is known as (, .)


Gamma Reticuli

Gamma Reticuli (Gamma Ret, γ Reticuli, γ Ret) is a solitary star in the southern constellation of Reticulum. With an apparent visual magnitude of 4.5, it can be faintly seen with the naked eye. Based upon an annual parallax shift of 6.95 mas, it is located roughly 469 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.08 due to interstellar dust.
This is an evolved red giant star, currently on the asymptotic giant branch, with a stellar classification of M4 III. It is a semiregular variable with a period of 25 days. Gamma Reticuli has 1.5−2 times the mass of the Sun, 115 times the Sun's radius, and radiates 1,846 times the solar luminosity from its outer atmosphere at an effective temperature of 3,450 K.
Gamma Reticuli is moving through the Galaxy at a speed of 24.8 km/s relative to the Sun. Its projected Galactic orbit carries it between 24,100 and 39,200 light years from the center of the Galaxy.


Malus (constellation)

Malus (Latin for "mast") was a subdivision of the ancient constellation Argo Navis proposed in 1844 by the English astronomer John Herschel. It would have replaced Pyxis, the compass, which was introduced in the 1750s by Nicolas Louis de Lacaille. Herschel's suggestion was not widely adopted and Malus is not now recognized by astronomers.
External links.
[[Category:Former constellations]]


68 Herculis

68 Herculis is a triple star system located around 990 light years away from the Sun in the northern constellation of Hercules. In the astronomical community it is more commonly referred to by its Bayer designation of u Herculis, while "68 Herculis" is the Flamsteed designation. The system is visible to the naked eye as a faint, blue-white hued point of light with a peak apparent visual magnitude of 4.80. It is approaching the Earth with a heliocentric radial velocity of −17 km/s.
The inner pair of this system form a well-studied semidetached binary with the orbital plane oriented near the line of sight to the Earth, making it an Algol-type eclipsing binary. They have an orbital period of just over two days and a semimajor axis of 15 times the radius of the Sun, with the secondary component transferring mass to the hotter primary star. The main eclipse reduces the magnitude of the system to 5.37, while the second eclipse lowers the brightness to magnitude 4.93. Theoretical calculations suggest the donor star began with 7.2 times the mass of the Sun, the current primary at 3.6 solar masses, and their initial orbital period was around 1.35 days.
The primary, designated component A, displays Beta Cephei-like pulsational behavior. It appears to be a B-type main-sequence star with a stellar classification of B2 V. The star has a high rate of spin, with a projected rotational velocity of 145 km/s. It has nearly eight times the mass of the Sun and five times the Sun's radius. The star is radiating 4,786 times the Sun's luminosity from its photosphere at an effective temperature of 21,600 K.
The secondary, component B, has proven difficult to classify, but appears as a B-type star of type B8−9. It is close to triple the mass of the Sun with 4.3 times the Sun's radius. The star is spinning with a projected rotational velocity of 105 km/s. It is radiating 426.5 times the Sun's luminosity from its photosphere at an effective temperature of 12,600 K.
The third member of this system, component C, lies at an angular separation of from the inner pair with a visual magnitude of 10.2.


NGC 534

NGC 534 is a lenticular galaxy located in the constellation of Sculptor about 260 million light years from the Milky Way. It was discovered by the British astronomer John Herschel in 1835.


NGC 5890

NGC 5890 is an unbarred lenticular galaxy in the constellation Libra. It was discovered in April 1785 by Ormond Stone.


NGC 7028

NGC 7028 is the designation of a celestial object in the constellation of Delphinus. The object was supposedly discovered by the German astronomer Albert Marth on 17 September 1863. However, its identification is uncertain, and the object is considered lost. No galaxies or nebulous objects are at the coordinates that he gave.
One candidate is a spiral galaxy designated UGC 11676, or CGCG 448-039. It has an apparent magnitude of 14.8, and is "very faint, small, very little extended", just as Marth described. While the declination of this object matches that of Marth's description, the right ascension is 2.5 arcminutes off.


NGC 7060

NGC 7060 is an intermediate spiral galaxy located about 200 million light-years away in the constellation of Microscopium. The spiral arms of NGC 7060 appear to overlap. NGC 7060 was discovered by astronomer John Herschel on September 2, 1836.
NGC 7060 is the dominant member of a small group of galaxies known as the NGC 7060 group. Other members of the group are NGC 7057, NGC 7072, and NGC 7072A.


Tau2 Serpentis

Tau2 Serpentis, Latinized from τ2 Serpentis, is a star in the constellation of Serpens, located approximately 480 light-years from the Sun. It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.22. The star is drifting closer with a radial velocity of −19 km/s.
This object is a late B-type main-sequence star with a stellar classification of B9V. It is a probable Lambda Boötis star. The star is 278 million years old and is spinning with a projected rotational velocity of 154 km/s. It has nearly three times the mass and radius of the Sun. Tau2 Serpentis is radiating 96 times the Sun's luminosity from its photosphere at an effective temperature of 10,839 K.
There is evidence of a possible companion, which is contributing about 15% to the total emission of the system.


Beta Mensae

Beta Mensae, Latinized from β Mensae, is the third-brightest star in the constellation of Mensa. Despite this, it is only faintly visible to the naked eye, appearing as a dim, yellow-hued point of light with an apparent visual magnitude of 5.31. The star is positioned near the southwest edge of the Large Magellanic Cloud, but it does not form part of this much more distant satellite galaxy. Based upon an annual parallax shift of just 4.11 mas as seen from the Earth, the star is located at a distance of roughly 790 light years from the Sun. It is moving closer with a heliocentric radial velocity of −11 km/s.
This is a solitary, G-type giant star with a stellar classification of G8 III. It is around 270 million years old with 3.6 times the mass of the Sun. Having exhausted the supply of hydrogen at its core, it has expanded to 26 times the Sun's radius. Beta Mensae is radiating 513 times the Sun's luminosity from its photosphere at an effective temperature of about 5,088 K.


HD 68988

HD 68988 is a star in the northern constellation of Ursa Major. It has been given the proper name Násti, which means star in the Northern Sami language. The name was selected in the NameExoWorlds campaign by Norway, during the 100th anniversary of the IAU. HD 68988 is too faint to be seen with the naked eye, having an apparent visual magnitude of 8.20. The star is located at a distance of 199 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −69 km/s and is predicted to come as close as in 617,000 years.
The stellar classification of HD 68988 has been given as G0V, G2V, and G2IV. The age of this star was estimated as six billion years in 2002, but was later revised down to one billion years in 2015. It is rotating slowly and is chromospherically inactive. The star has 16% more mass than the Sun and an 8% greater radius with a high metallicity; what astronomers term the abundance of heavier elements. It is radiating 1.3 times the luminosity of the Sun from its photosphere at an effective temperature of 5,919 K.
Planetary system.
There are two exoplanet: HD 68988 b was discovered in 2002 and HD 68988 c was discovered in 2006. The orbit of the inner exoplanet is surprisingly eccentric for such a close in orbit, and over time it may become circularized.


Gamma Capricorni

Gamma Capricorni (γ Capricorni, abbreviated Gamma Cap, γ Cap), named Nashira , is a giant star in the constellation of Capricornus. Based on parallax measurements obtained during the Hipparcos mission, it is about 139 light-years from the Sun. It is 2.56 degrees south of the ecliptic, so it can be occulted by the Moon, and (rarely) by planets.
Nomenclature.
"γ Capricorni" (Latinised to "Gamma Capricorni") is the star's Bayer designation.
It bore the traditional name "Nashira", derived from the Arabic سعد ناشرة "sa'd nashirah" "the lucky one" or "bearer of good news". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name "Nashira" for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Line of Ramparts", refers to an asterism consisting of Gamma Capricorni, Kappa Capricorni, Epsilon Capricorni, Delta Capricorni, Iota Aquarii, Sigma Aquarii, Lambda Aquarii, Phi Aquarii, 27 Piscium, 29 Piscium, 33 Piscium and 30 Piscium. Consequently, the Chinese name for Gamma Capricorni itself is (, ).
Namesake.
Nashira (AK-85) was a United States Navy ship, though it was never commissioned and never bore the USS designation.
Properties.
γ Capricorni is a hot chemically peculiar Am star with a mean apparent magnitude of +3.67. It is classified as an α2 Canum Venaticorum type variable star and its brightness varies by 0.03 magnitudes.


Alpha Pyxidis

Alpha Pyxidis (Alpha Pyx, α Pyxidis, α Pyx) is a giant star in the constellation Pyxis. It has a stellar classification of B1.5III and is a Beta Cephei variable. This star has more than ten times the mass of the Sun and is more than six times the Sun's radius. The surface temperature is 24,300 K and the star is about 10,000 times as luminous as the Sun. Stars such as this with more than 10 solar masses are expected to end their life by exploding as a supernova.
Naming.
In Chinese, (), meaning "Celestial Dog", refers to an asterism consisting of α Pyxidis, e Velorum, f Velorum, β Pyxidis, γ Pyxidis and δ Pyxidis. Consequently, α Pyxidis itself is known as (, .)


68 Aquilae

68 Aquilae (abbreviated 68 Aql) is a double star in the equatorial constellation of Aquila. "68 Aquilae" is its Flamsteed designation. Its apparent magnitude is 6.12.


Epsilon Ceti

Epsilon Ceti, Latinized from ε Ceti, is the Bayer designation for a binary star system located in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of +4.84. Based upon an annual parallax shift of 14.58 mas, it is located around 98 light years away from the Sun.
This is a line-width spectroscopic binary star system. It has an orbital period of 2.65 years and an eccentricity of 0.23. The semimajor axis is 0.11 AU, or 11% of the distance between the Sun and the Earth, and the orbital plane is inclined at an angle of 24.2°.The primary member, component A, is an F-type main sequence star with a stellar classification of F2 V. The spectrum of the secondary, component B, can not be readily separated from that of the primary, so its type can only be estimated as a main sequence star lying in the range between F7 V and G4 V. The system is estimated to be 1.8 billion years old, with the primary having 1.4 times the mass of the Sun and the secondary being about equal to the Sun's mass.
Name.
This star, along with π Cet, ρ Cet and σ Cet, was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's Breast
According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Sadr al Ḳaiṭos" were the title for four stars :ρ Cet as "Al Sadr al Ḳaiṭos I", σ Cet as "Al Sadr al Ḳaiṭos II", this star (ε Cet) as "Al Sadr al Ḳaiṭos III" and π Cet as "Al Sadr al Ḳaiṭos IV"
In Chinese, (), meaning "Hay", refers to an asterism consisting of ε Ceti, ρ Ceti, 77 Ceti, 67 Ceti, 71 Ceti and HD 14691. Consequently, the Chinese name for ε Ceti itself is (, .


HVS 7

HVS 7 -- hyper-velocity star 7, otherwise known as SDSS J113312.12+010824.9 is a rare star that has been accelerated to faster than our Milky Way Galaxy's escape velocity. In 2013 a team under N. Przybilla wrote that the star had a chemically peculiar photosphere, which masked its origins. The star was first cataloged during the Sloan Digital Sky Survey. It was identified as a hyper-velocity star in 2006.
The star has a chemically peculiar spectrum, roughly matching a B-type subdwarf. Stars in this region of the Hertzsprung–Russell diagram are expected to either be hot horizontal branch stars, low-mass helium-burning objects, or moderate mass hydrogen-burning stars slightly below the main sequence. The high rotational velocity of HVS 7 means it is likely to be a young star near the main sequence, around 150 million years old and 3.7 times the mass of the sun.


R Arae

R Arae is an Algol-type eclipsing binary in the constellation Ara. Located approximately distant, it normally shines at magnitude 6.17, but during eclipses can fall as low as magnitude 7.32. It has been suggested by multiple studies that mass transfer is occurring between the two stars of this system, and the period of eclipses seems to be increasing over time. The primary is a blue-white main sequence star of spectral type B5V that is 5 times as massive as the Sun, while the secondary is a yellow-white star of spectral type F1IV that is 1.5 times as massive as the Sun. Stellar material is being stripped off the secondary and accreting on the primary.
R Arae has an 8th-magnitude companion away. The companion star is at a similar distance.


Phi Herculis

Phi Herculis (φ Her) is a binary star system in the northern constellation of Hercules. Based upon an annual parallax shift of 15.99 mas as seen from Earth, it is located around 204 light years from the Sun. With a combined apparent visual magnitude of 4.24, it is bright enough to be seen with the naked eye.
This is a single-lined spectroscopic binary star system with an orbital period of 564.8 days and an eccentricity of 0.526. The primary, component A, is a B-type main sequence star with a stellar classification of B9VspHgMn. It is a chemically peculiar star of the type called a mercury-manganese star. The star is tentatively cataloged as an Alpha2 Canum Venaticorum variable.
The secondary, component B, was first separated via interferometry in 2004. It is an A-type main sequence star of class A8V. The magnitude difference between the two components is 2.64.


U Antliae

U Antliae (U Ant) is a variable star in the constellation Antlia. It is a carbon star surrounded by two thin shells of dust.
U Antliae is an extremely red C-type carbon star. These cool stars on the asymptotic giant branch are further reddened by strong mass loss and dust that forms around the star. U Antliae is calculated to have an effective surface temperature of , although the light that reaches us has an appearance more like that from a black body with a temperature of surrounded by dust at a temperature of . It emits most of its radiation in the infrared and although it is only about 500 times brighter than the sun at visual wavelengths, its bolometric luminosity is 8,000 times higher than the Sun's.
U Antliae and is an irregular variable star with an apparent magnitude that varies between 5.27 and 6.04. Approximately 900 light years from Earth, it is surrounded by two shells of dust, thought to have been ejected 14,000 and 10,000 years ago. The exact origin and structure of the shells is uncertain, possibly due to enhanced mass loss during thermal pulses, possibly due to interaction of the stellar wind with interstellar material.


HD 30963

HD 30963 is a star in the constellation of Eridanus. With an apparent magnitude of 7.23, it cannot be seen with the naked eye. Parallax measurements made by Hipparcos put the star at a distance of around 900 light-years (280 parsecs) away.
HD 30963 is a late B-type star. It is a mercury-manganese star, a class of chemically peculiar star that has an overabundance of certain elements like mercury. HD 30963 has 150,000 times as much mercury, 2,500 times as much platinum, 1,000 times as much yttrium, and 150 times as much zirconium compared to the Sun. It has a mass of , and its surface temperature is about 11,500 K.
HD 30963 is close to the orbit that the solar system is traversing in the Milky Way. The sun will be close to the current location of HD 30963 in about 18.5 million years. Interstellar absorption lines for Na I are present for velocities lower than 10 km/s.


Pi Leonis

Pi Leonis, Latinized from π Leonis, is a single star in the zodiac constellation Leo. It is a red hued star that is visible to the naked eye with an apparent visual magnitude of 4.70. This object is located at a distance of some 410 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +22 km/s. Because the star lies near the ecliptic it is subject to occultations by the Moon.
This is an evolved, red giant star with a stellar classification of M2 III. With the supply of hydrogen at its core exhausted, it has expanded to 70 times the Sun's radius. The star shines with 1,077 times the luminosity of the Sun from an expanded outer atmosphere that has an effective temperature of 3,956 K. According to the "General Catalogue of Variable Stars", it is a suspected variable star with a maximum magnitude of 4.67.


NGC 3244

NGC 3244 is a spiral galaxy in the Antlia constellation discovered by John Herschel on April 22, 1835. A supernova was detected in NGC 3244 on June 27, 2010, designated SN 2010ev. With an apparent magnitude of about 14, it was the third-brightest supernova observed in 2010.


List of stars in Sculptor

This is the list of notable stars in the constellation Sculptor, sorted by decreasing brightness.


V923 Aquilae

V923 Aquilae is a variable binary star system in the equatorial constellation of Aquila. It has the designation HD 183656 from the "Henry Draper Catalogue"; V932 Aql is the variable star designation. The system is dimly visible to the naked eye with an apparent visual magnitude that fluctuates around 6.06. It is located at a distance of approximately 890 light years from the Sun based on parallax, but is drifting closer with a radial velocity of around −26 km/s.
This system was first identified as a likely spectroscopic binary by W. E. Harper in 1937, who noted it showed "narrow intense lines of peculiar spectrum". P. W. Merrill and C. G. Burwell identified it as a shell star in 1949. Merrill and A. L. Lowen showed in 1953 that the shell displayed large radial velocity variations. A photometric study by C. R. Lynds in 1960 showed the system varied in brightness with an amplitude of more than 0.1 in magnitude and a characteristic period of 0.85 days, although it doesn't behave periodically over long time intervals.
A more thorough investigation by P. Koubský and associates in 1989 using long-term radial velocity measurements determined this is a spectroscopic binary with an orbital period of 214.75 days. There is also an overlaying long-term cyclical variation of changing amplitude and period. The modelled binary system shows a primary with a class of around B5–7e and a low mass secondary separated by around 250 times the radius of the Sun (). They hypothesized that the long-term variation was due to an envelope created by a mass transfer from the secondary component to the primary. However, the mass transfer concept was later brought into question and remains unverified as of 2004.


NGC 3227

NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the "Atlas of Peculiar Galaxies". Both galaxies may be found in the constellation Leo.
Sir William Herschel already recognised them as a 'double nebula' and they were jointly listed as Holm 187 in the "Catalogue of Double and Multiple Galaxies" and as Arp 94 in the "Atlas of Peculiar Galaxies". Amateur telescopes can discern them but require magnification of about 100 times. They are situated 50′ east of the well-known double star system Gamma Leonis (i.e. Algieba).
Nucleus.
NGC 3227 contains a Seyfert nucleus, a type of active galactic nucleus (AGN). Such Seyfert nuclei typically contain supermassive black holes. This object has an estimated mass of .
As is typical of many AGN, the nucleus of NGC 3227 has been identified as a source of variable X-ray emission. This variability occurs on time scales ranging from a few hours to a few months. The variability may be caused by variations in the density or ionization of gas and dust near the AGN that absorb the X-ray emission. A substantial amount of the X-ray-absorbing gas may lie within 0.4 parsec (1.3 light-years) of the nucleus. An observed change in the shape of the X-ray spectrum in 2000 and 2001 suggests that some of the X-ray absorbing gas is located within 10–100 light-days of the nucleus.
The luminosity of the nucleus reached a maximum in 1977 when evidence suggesting long-lived one-sided or two-sided gas streams was obtained.
X-ray radiation of the central accretion disc is reprocessed in one to two days to be re-emitted in the optical spectrum. Infra-red light emission from the hot dust torus lags optical light emission from the nucleus by about 20 days in NGC 3227. The temperature of the dust torus is estimated at 1500 K to 1800 K in NGC 3227 and similar galaxies.
This galaxy was studied by the Multicolor Active Galactic Nuclei Monitoring 2m telescope.


HR 4796

HR 4796 is a binary star system in the southern constellation of Centaurus. Parallax measurements put it at a distance of from the Earth. The two components of this system have an angular separation of 7.7 arcseconds, which, at their estimated distance, is equivalent to a projected separation of about 560 Astronomical Units (AU), or 560 times the separation of the Earth from the Sun. The star and its ring resemble an eye, and it is sometimes known by the nickname "Sauron's Eye".
Components.
This is a young system with an estimated age of about 8 million years. The primary member A has a stellar classification of A0 V, while its smaller companion B is a red dwarf with a classification of M2.5 V. The luminosity class of 'V' indicates that both stars belong to the main sequence and are generating energy through the thermonuclear fusion of hydrogen at their cores. The primary is emitting this energy from its outer envelope at an effective temperature of about 9,378 K, which gives it the white hue characteristic of A-type stars. It has a radius about 168% of the radius of the Sun and 218% of the Sun's mass. By comparison, the secondary has only 30% of a solar mass. The abundance of elements other than hydrogen or helium, what astronomers term the star's metallicity, is similar to the proportion in the Sun.
Debris disk.
In 1991, the primary was found to have an excess of infrared emission, implying that it has a circumstellar debris disk. Observations using the Near-Infrared Multi-Object Spectrometer aboard the Hubble Space Telescope in 2007 indicated that the dust had a reddish spectrum similar to that of tholins. The disk was resolved with the Hubble Space Telescope in 2009, confirming that it exists. Based on these images, the disk has a radius of 75 AU and a width of less than 18.5 AU. It may have some asymmetries and the center appears to be slightly offset from the star. The dust in the disk is likely the result of collisions between larger particles. In 2011, observations of the ring offset by the Subaru Telescope implies that one or more planets would likely exist within gaps tugging at its dust grains. With a new image in 2014, the configuration and alignment of the dust ring and HR4796A has been nicknamed "Eye of Sauron".
In 2017 a group using NASA/IRTF and Spitzer infrared spectroscopy of the infrared excess determined that the bright narrow ring is made up of very red devolatilzed cometary material, and that a second faint, hot diffuse dust component likely due to inspiralling material escaping from the ring was present close to the star and evaporating. The discovery of a complex dust structure about 1,600 AU across, enveloping HR 4796A, was announced in March 2018. The structure is believed to have been formed by the pressure of starlight from HR 4796A expelling dust from the debris disk far into space. The structure is much more extended in one direction than the other, possibly due to either the motion of HR 4796A through the interstellar medium, or the gravitational influence of HR 4796B.
Kinematics.
The space velocity of HR 4796 in the Galactic coordinate system is = . This trajectory and the location of the system suggests that it may be a member of the TW Hydrae association of stars that share a common origin. A low-mass member of this association, identified as 2MASS J12354893−3950245, may be a tertiary component of the HR 4796 system. It has a proper motion matching HR 4796, suggesting it is gravitationally bound to the other two stars, and is separated from the pair by a distance of about 13,500 AU.


Psi2 Orionis

Psi2 Orionis a binary star system in the equatorial constellation of Orion. It has an apparent visual magnitude of 4.60, indicating that it is visible to the naked eye. Based upon an annual parallax shift of 2.87 mass, it is roughly 1,100 light years distant from the Sun.
This is a double-lined spectroscopic binary, which means that the individual absorption lines of both components can be discerned. The pair orbit each other with a period of 2.526 days and a low eccentricity of 0.04. The close orbit is causing their mutual gravitational interaction to distort the shapes of the stars, turning this system into an ellipsoidal variable. The inclination of orbital plane is sufficiently low that the two stars form a grazing eclipsing binary. During the eclipse of the primary component, the visual magnitude is reduced by 0.06, whereas the secondary eclipse reduces the magnitude by 0.03.
The combined spectrum of Psi2 Orionis matches that of a B-type subgiant star with a stellar classification of B2 IV. The primary component is an evolved giant star with a class of B1 III, while the secondary is a B-type main sequence star with a classification of B2 V.


Mu Ophiuchi

μ Ophiuchi, Latinized as Mu Ophiuchi, is a solitary, blue-white hued star in the equatorial constellation of Ophiuchus. It is visible to the naked as a faint point of light with an apparent visual magnitude of 4.62. This object is located approximately 760 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −18.5 km/s.
This object has a stellar classification of B8II-IIIp:Mn, showing a luminosity class with mixed traits of a giant or bright giant star. The suffix notation indicates it is a candidate chemically peculiar star with an overabundance of manganese in its spectrum. It may be a mercury-manganese star. This object has 11 times the radius of the Sun and is radiating nearly 400 times the Sun's luminosity from its photosphere at an effective temperature of 7,748 K. It is spinning with a projected rotational velocity of 95 km/s.
In 2006, a new nearby star cluster, Mamajek 2 (), was discovered. Mu Ophiuchi is a candidate member. The cluster has an estimated age of  million years.


HD 290327 b

HD 290327 b (also known as HIP 25191 b) is an extrasolar planet which orbits the G-type subgiant star HD 290327, located approximately 180 light years away in the constellation Orion. This planet has at least five halves the mass of Jupiter and takes 6.7 years to orbit the star at a semimajor axis of 3.35 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.


Alpha Herculis

Alpha Herculis (α Herculis, abbreviated Alpha Her, α Her), also designated 64 Herculis, is a multiple star system in the constellation of Hercules. Appearing as a single point of light to the naked eye, it is resolvable into a number of components through a telescope. It has a combined apparent magnitude of 3.08, although the brightest component is variable in brightness. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 360 light-years (110 parsecs) distant from the Sun.
System.
Alpha Herculis is a triple star system. The primary (brightest) of the three stars, designated α1 Herculis or α Herculis A, is a pulsating variable star on the asymptotic giant branch (AGB), and is the second nearest AGB star after Mira. The primary star forms a visual binary pair with a second star, which is itself a spectroscopic binary.
Alpha Herculis also forms the A and B components of a wider system designated WDS J17146+1423, with two additional faint visual companions designated WDS J17146+1423C and D. The two fainter stars are far more distant than the triple system.
Nomenclature.
"α Herculis" (Latinised to "Alpha Herculis") is the system's Bayer designation; "α1" and "α2 Herculis", those of its two visible components. "64 Herculis" is the system's Flamsteed designation. WDS J17146+1423 is the wider system's designation in the Washington Double Star Catalog. The designations of Alpha Herculis' main components as "Alpha Herculis A" and "B" and the wider system's four components as WDS J17146+1423A, B, C and D, together with the spectroscopic pair - "Alpha Herculis Ba" and "Bb" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Alpha Herculis bore the traditional name "Rasalgethi" or "Ras Algethi" ( 'Head of the Kneeler'). 'Head' comes from the fact that in antiquity Hercules was depicted upside down on maps of the constellation. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name "Rasalgethi" for the component Alpha Herculis A (α1) on 30 June 2016 and it is now so included in the List of IAU-approved Star Names.
The term "ra's al-jaθiyy" or "Ras al Djathi" appeared in the catalogue of stars in the "Calendarium" of Al Achsasi al Mouakket, which was translated into Latin as "Caput Ingeniculi".
In Chinese astronomy, Alpha Herculis is called 帝座, Pinyin: Dìzuò, meaning 'Emperor's Seat', this star is marking itself and stands alone in the center of the "Emperor's Seat" asterism, Heavenly Market enclosure (see : Chinese constellations). 帝座 (Dìzuò) was westernized into "Ti Tso" by R.H. Allen, with the same meaning
Properties.
Alpha Herculis A and B are more than 500 AU apart, with an estimated orbital period of approximately 3600 years. A presents as a relatively massive red bright giant, but radial velocity measurements suggest a companion with a period of the order of a decade. B's two components are a primary yellow giant star and a secondary, yellow-white dwarf star in a 51.578 day orbit.
Alpha Herculis A is an asymptotic giant branch (AGB) star, a luminous red giant that has both hydrogen and helium shells around a degenerate carbon-oxygen core. It is the second nearest AGB star to the Sun. The angular diameter of the star has been measured with an interferometer as
34 ± 0.8 mas, or 0.034 arcseconds. At its estimated distance of 110 parsecs this corresponds to a radius of about 280 million kilometers (or 170 million miles), which is roughly or 1.87 AU. If Alpha Herculis were at the center of the Solar System its radius would extend past the orbit of Mars at 1.5 AU but not quite as far as the asteroid belt. The red giant is estimated to have started its life with about .
Alpha Herculis A has been specified as a standard star for the spectral class M5 Ib-II. Like most type M stars near the end of their lives, Alpha Herculis is experiencing a high degree of stellar mass loss creating a sparse, gaseous envelope that extends at least 930 AU. It is a semiregular variable with complex changes in brightness with periods ranging from a few weeks to many years. The most noticeable variations occur at timescales of 80–140 days and at 1,000 - 3,000 days. The strongest detectable period is 128 days. The full range in brightness is from magnitude 2.7 to 4.0, but it usually varies over a much smaller range of around 0.6 magnitudes.


HD 9986

HD 9986 is a Sun-like star in the equatorial constellation of Pisces. With an apparent visual magnitude of 6.77, it lies below the normal limit for visibility with the naked eye. The star is located at a distance of 83 light years from the Sun as determined from parallax measurements, but it is drifting closer with a radial velocity of −21 km/s.
This object is a G-type main-sequence star with a stellar classification of G5 V, and is a near solar twin with physical properties very similar to the Sun's. It is around 3.3 billion years old and is spinning slowly with a rotation period of about 23 days. A speckle survey of G-dwarfs by Elliott P. Horch in 2002 noted that HD 9986 may not be non-single star.