25 Canum Venaticorum

25 Canum Venaticorum is a binary star system in the northern constellation of Canes Venatici, approximately 199 light years from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of +4.82 The system is moving closer to the Earth with a heliocentric radial velocity of roughly −10 km/s.
This is a wide binary system with an orbital period of 228 years and an eccentricity of 0.80. As of 2001, they had a projected separation of . The magnitude 4.98 primary, component A, has a stellar classification of , which matches an A-type giant star. It is 659 million years old with a projected rotational velocity of 235 km/s. This rate of spin is giving the star an oblate shape with an equatorial bulge that is an estimated 27% larger than the polar radius. The companion, component B, is a magnitude 6.95 A-type main-sequence star with a class of A8 V:. The ':' suffix indicates some uncertainty in the classification of this star.


HFLS3

HFLS3 is the name for a distant galaxy at "z =" 6.34, originating about 880 million years after the Big Bang. Its discovery was announced on 18 April 2013 as an exceptional starburst galaxy producing nearly 3,000 solar masses of stars a year. It was found using the far-infrared-capable Herschel Space Telescope. The galaxy was estimated to have 35 billion stars. It is 10–30 times the mass of other known galaxies at such an early time in the universe.
HFLS3 was subjected to a follow-up campaign by other telescopes due to its high redness. It was found in the HerMES campaign, which also found other very red sources.


Iota Trianguli

Iota Trianguli, Latinized from ι Trianguli, is a quadruple star system in constellation of Triangulum. It is approximately 290 light years from Earth.
Both components of ι Trianguli are spectroscopic binaries and the brighter pair is variable. It has been given the variable star designation TZ Trianguli. The variations are due to the ellipsoidal shape of the stars as they rotate, and also it is classified as an RS Canum Venaticorum variable.


Alpha Leporis

Alpha Leporis (α Leporis, abbreviated Alpha Lep, α Lep), formally named Arneb , is the brightest star in the constellation of Lepus.
Nomenclature.
"Alpha Leporis" is the star's Bayer designation. The traditional name "Arneb" comes from the Arabic "أرنب" "’arnab" 'hare' ('Lepus' is Latin for hare). 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 "Arneb" for this star.
In Chinese, (), meaning "Toilet", refers to an asterism consisting of α Leporis, β Leporis, γ Leporis and δ Leporis. Consequently, the Chinese name for α Leporis itself is (), "the First Star of Toilet".
Properties.
This is a massive star with about 14 times the mass of the Sun. The interferometer-measured angular diameter of this star, after correction for limb darkening, is . At an estimated distance of , this yields a physical size of about 129 times the radius of the Sun. Alpha Leporis has a stellar classification of F0 Ib, with the Ib luminosity class indicating that it is a lower luminosity supergiant star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. The effective temperature of the outer envelope is about 6,850 K, which gives the star a yellow-white hue that is typical of F-type stars. It is an estimated 13 million years old.
Alpha Leporis is an older, dying star that may have already passed through a supergiant phase and is now contracting and heating up in the latter phases of stellar evolution, or perhaps is still expanding into the supergiant phase. Based upon its estimated mass, it is expected to end its life in a spectacular stellar explosion known as a supernova. However, this is not expected to happen for another million years.
Arneb in Military.
USS Arneb (AKA-56) was a ship of the United States navy.
References.
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G 29-38

Giclas 29-38, also known as ZZ Piscium, is a variable white dwarf star of the DAV, or ZZ Ceti,
whose variability is due to large-amplitude, non-radial pulsations, known as gravity waves. It was first reported to be variable by Shulov and Kopatskaya in 1974. DAV stars are like normal white dwarfs but have luminosity variations with amplitudes as high as 30%, arising from a superposition of vibrational modes with periods from 100 to 1,000 seconds. Large-amplitude DAVs generally differ from lower-amplitude DAVs by having lower temperatures, longer primary periodicities, and many peaks in their vibrational spectra with frequencies which are sums of other vibrational modes.
G29-38, like other complex, large-amplitude DAV variables, has proven difficult to understand. The power spectrum or periodogram of the light curve varies over times which range from weeks to years. Usually, one strong mode dominates, although many smaller-amplitude modes are often observed. The larger-amplitude modes, however, fluctuate in and out of observability; some low-power areas show more stability. Asteroseismology uses the observed spectrum of pulsations from stars like G29-38 to infer the structure of their interiors.
Debris disk.
The circumstellar environment of G29-38 first attracted attention in the late 1980s during a near-infrared survey of 200 white dwarfs conducted by Ben Zuckerman and Eric Becklin to search for low mass companion stars and brown dwarfs. G29-38 was shown to radiate substantial emission between 2 and 5 micrometres, far in excess of that expected from extrapolation of the visual and near infrared spectrum of the star. Like other young, hot white dwarfs, G29-38 is thought to have formed relatively recently (600 million years ago) from its AGB progenitor, and therefore the excess was naturally explained by emission from a Jupiter-like brown dwarf with a temperature of 1200 K and a radius of 0.15 solar radius. However, later observations, including speckle interferometry, failed to detect a brown dwarf.
Infrared observations made in 2004 by NASA's Spitzer Space Telescope indicated the presence of a dust cloud around G29-38, which may have been created by tidal disruption of an exocomet passing close to the white dwarf. This may mean that G29-38 is still orbited by a ring of surviving comets and, possibly, outer planets. This is the first observation supporting the idea that comets persist to the white dwarf stage of stellar evolution.


NGC 235

NGC 235 is a lenticular galaxy in the constellation of Cetus. Its companion, PGC 2570, appears in the line of sight of NGC 235, but has no relation with NGC 235. This pair was first discovered by Francis Leavenworth in 1886. Dreyer, the compiler of the catalogue, described the galaxy as "extremely faint, small, round, brighter middle and nucleus".


KKh 060

KKH 060 is an irregular galaxy and a low surface brightness galaxy located in the direction of the constellation Leo at a distance of 4.89 million light years from Earth. The galaxy is close to the Local Group, but is not considered to be a member of it.


Mz 3

Mz 3 (Menzel 3) is a young bipolar planetary nebula (PN) in the constellation Norma that is composed of a bright core and four distinct high-velocity outflows that have been named lobes, columns, rays, and chakram. These nebulosities are described as: two spherical bipolar lobes, two outer large filamentary hour-glass shaped columns, two cone shaped rays, and a planar radially expanding, elliptically shaped chakram.
Mz 3 is a complex system composed of three nested pairs of bipolar lobes and an equatorial ellipse.
Its lobes all share the same axis of symmetry but each have very different morphologies and opening angles.
It is an unusual PN in that it is believed, by some researchers, to contain a symbiotic binary at its center.
One study suggests that the dense nebular gas at its center may have originated from a source different from that of its extended lobes. The working model to explain this hypothesizes that this PN is composed of a giant companion that caused a central dense gas region to form, and a white dwarf that provides ionizing photons for the PN.
Mz 3 is often referred to as the Ant Nebula because it resembles the head and thorax of a garden-variety ant.
Characteristics.
Mz 3 is radially expanding at a rate of about 50 km/s and has its polar axis oriented at an angle of around 30° from the plane of the sky (Lopez & Meaburn 1983; Meaburn & Walsh 1985). It is sometimes compared to the more extensively studied Butterfly Nebula (M 2-9), and it is quite likely that both have a similar evolutionary history. They both have point-like bright nuclei, are narrow-waisted bipolar nebulae, and share surprisingly similar spatially dependent spectra. Because of their similarity, their differences are noteworthy. Their greatest difference is probably in their near infrared emissions. Mz 3 has no trace of molecular hydrogen emission, whereas the M 2-9 has prominent H2 emission lines in the near-IR. The lack of H2 emissions from Mz 3 is unusual given the strong correlation between such emissions and bipolar structures of PN. Additionally, the polar lobes of Mz 3 are more mottled and rounded as compared to M 2-9. Finally, Mz 3 is not known to evidence temporal variability in its polar lobes as is found in M 2-9 (Doyle et al. 2000).
The Herschel Space Observatory has detected laser light emissions from the nebula -- specifically, hydrogen recombination line laser emissions. This confirms the presence of a white dwarf with a binary companion at the heart of the nebula.
Chakram.
Of the morphological features of Mz 3, one of the most unusual and odd is the chakram (first noticed in 2004), a faint, large, limb brightened ellipse that appears to have its center on the PN's nucleus. While the plane of the ellipse is near the other feature's shared reflection symmetry plane, it is definitely offset. This structure's kinematics are the only such ones known among studied PN. Unlike all the other Mz 3 structures, there is no increase of velocity as the radial offset from the nucleus increases. Consequently, this must not be a simple equatorial flow despite the fact that its motion appears to be strictly radial (that is, there is no indication of rotation which would suggest that this feature is dynamically stable). All the kinematic properties of the ellipse are symmetric and very ordered relative to the nucleus, consistent with all the other Mz 3 features. Therefore, the ellipse must be historically linked to the evolution of the central star.
The Ant Nebula is 8,000 light years away from Earth and it has a magnitude of 13.8
History.
Mz 3 was discovered by Donald Howard Menzel in 1922.
It was studied on July 20, 1997 by astronomers Bruce Balick (University of Washington) and (Leiden University) on observations done with the Hubble Space Telescope. The telescope was later used on June 30, 1998 by Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory to picture the PN.


Carina OB2

Carina OB2 is a giant OB association in the constellation Carina. It contains anywhere from 91 to 157 stars, many of which are hot blue stars of spectral types B and O. It is located 3.1 kiloparsecs distant and is around 4 million years old.


B Carinae

The Bayer designations b Carinae and B Carinae are distinct and the designation b Carinae is shared by two stars in the constellation Carina:
See also.
β Carinae


F Cygni

The Bayer designation f Cygni is shared by two stars in the constellation Cygnus:


AE Aurigae

AE Aurigae (abbreviated as AE Aur) is a runaway star in the constellation Auriga; it lights the Flaming Star Nebula.
Description.
AE Aurigae is a blue O-type main sequence dwarf with a mean apparent magnitude of +6.0. It is classified as an Orion type variable star and its brightness varies irregularly between magnitudes +5.78 and +6.08. It is approximately 1,300 light-years from Earth.
AE Aur is a runaway star that might have been ejected during a collision of two binary star groups. This collision, which also is credited with ejecting Mu Columbae and possibly 53 Arietis, has been traced to the Trapezium cluster in the Orion Nebula two million years ago. The binary Iota Orionis may have been the other half of this collision.
AE Aur is seen to light up the Flaming Star nebula, but it was not formed within it. Instead it is passing through the nebula at high speed and producing a violent bow shock and high energy electromagnetic radiation.
Companions.
Possibly due to its runaway star nature, AE Aurigae has no physical companion stars, although some nearby stars have been erroneously identified as ones. A theoretical companion 1000 AU (0.016 light-years) away from AE Aurigae would have an angular separation of less than 2.5 arcseconds and would probably be lost in the star's glare.


NGC 6603

NGC 6603 is an open cluster discovered by John Herschel on July 15, 1830 located in Sagittarius constellation.
Situated within the brightest part of star cloud Messier 24, it is classified by Shapley as type "g". This cluster consists of about 30 stars in a field of about 5 arc minutes in diameter, and is about 9400 light years remote. Thus its linear diameter should be about 14 light years. The hottest stars are about B9 (pointing to an intermediate age of several 100 million years, an estimate of which is not known to the present author), and the brightest of photographic mag 14.
Many sources improperly identify NGC 6603 as Messier 24.


Psi Velorum

Psi Velorum (ψ Vel, ψ Velorum) is a binary star system in the southern constellation of Vela. Based upon an annual parallax shift of 53.15 mas as seen from Earth, it is located 61.4 light years from the Sun. It is visible to the naked eye with a combined apparent visual magnitude of +3.58. The motion of this system through space makes it a candidate member of the Castor stellar kinematic group.
The two components of this system orbit their common barycenter with a period of 33.95 years and an eccentricity of 0.433. The semimajor axis of their orbit has an angular size of 0.862 arc seconds. The primary, component A, is a yellow-white hued F-type subgiant with an apparent magnitude of +3.91 and a stellar classification of F0 IV. The fainter secondary, component B, is also an F-type subgiant of magnitude +5.12 and class F3 IV. It has been reported to be variable between magnitude 4.5 and 5.1.


NGC 3686

NGC 3686 is a spiral galaxy that forms with three other spiral galaxies, NGCs 3681, 3684, and 3691, a quartet of galaxies in the Leo constellation. It was discovered on 14 March 1784 by William Herschel.


Alpha Coronae Australis

Alpha Coronae Australis (α Coronae Australis, abbreviated Alf CrA, α CrA), officially named Meridiana , is the brightest star in the constellation of Corona Australis and is located about 125 light-years from Earth.
Nomenclature.
"α Coronae Australis" (Latinised to "Alpha Coronae Australis") is the star's Bayer designation.
It is the only star in the constellation with a traditional proper name, "Alphekka Meridiana" (Latin for 'Alphekka South'), after "Alphecca", the brightest star in the constellation Corona Borealis. The name "Alphecca" or "Alphekka" is Arabic, short for نير الفكّة "nayyir al-fakka" "the bright (star) of the broken (ring of stars)". 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 "Meridiana" for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "River Turtle", refers to an asterism consisting of Alpha Coronae Australis, Alpha Telescopii, Eta¹ Coronae Australis, Zeta Coronae Australis, Delta Coronae Australis, Beta Coronae Australis, Gamma Coronae Australis, Epsilon Coronae Australis, HD 175362, Kappa² Coronae Australis and Theta Coronae Australis. Consequently, the Chinese name for Alpha Coronae Australis itself is (, .).
Properties.
Alpha Coronae Australis belongs to the spectral class A2Va, making it an A-type star like Vega. Like the latter, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It has an apparent magnitude of +4.10. The star's mass and radius are estimated at 2.3 times the Sun's mass and radius. With an effective temperature of roughly 9,100 K, the star radiates a total luminosity of about 31 times the Sun's. This star is roughly 254 million years old. A rapidly rotating star, it spins at almost 200 km per second at the equator, making a complete revolution in approximately 14 hours, close to its breakup velocity.


Kappa Hydrae

κ Hydrae, Latinised as Kappa Hydrae, is a solitary star in the equatorial constellation of Hydra. Its apparent visual magnitude is 5.06, which is bright enough to be faintly visible to the naked eye. The distance to this star is around , based upon an annual parallax shift of 7.48 mas. It may be a variable star, meaning it undergoes repeated fluctuations in brightness by at least 0.1 magnitude.
This is an evolving B-type star with a stellar classification of B4 IV/V, having a luminosity class intermediate between a subgiant and a giant star. It has an estimated five times the mass of the Sun and 3.4 times the Sun's radius. Kappa Hydrae has a high rate of spin with a projected rotational velocity of 115.0 km/s, and is only about 31 million years old. The star radiates 328 times the solar luminosity from its outer atmosphere at an effective temperature of 16,150 K.
Name.
This star was one of the set assigned by the 16th century astronomer Al Tizini to Al Sharāsīf (ألشراسيف), the Ribs (of Hydra), which included the stars from β Crateris westward through κ Hydrae.
According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Sharāsīf" were the title for two stars : β Crateris as "Al Sharasīf II" and κ Hydrae as "Al Sharasīf I".
In Chinese, (), meaning "Extended Net", refers to an asterism consisting of Kappa Hydrae, Upsilon1 Hydrae, Lambda Hydrae, Mu Hydrae, HD 87344, and Phi1 Hydrae. Consequently, Kappa Hydrae itself is known as (), "the Fifth Star of Extended Net".


NGC 4296

NGC 4296 is a barred lenticular galaxy located about 200 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on April 13, 1784. It forms a pair with NGC 4297, and both galaxies are listed as CGCG 042-041, and KPG 331.
It also interacts with NGC 4297.


Gamma Octantis

The Bayer designation γ Octantis (gamma Octantis, γ Oct) is shared by three stars, in the constellation Octans, all yellow giants:


NGC 397

NGC 397 is a lenticular galaxy located in the constellation Pisces. It was discovered on December 6, 1866 by Robert Ball. It was described by Dreyer as "extremely faint, small, round, very faint star to west."


AD Andromedae

AD Andromedae (AD And) is an eclipsing binary in the constellation Andromeda. Its maximum apparent visual magnitude is 11.2, but it shows a decrease of 0.62 magnitudes during the main eclipse and 0.58 during the secondary one. It is classified as a Beta Lyrae variable star with a period of almost one day.
System.
The AD Andromedae system consists of two close main sequence stars of spectral type A0V. They orbit so close to each other that they have an ellipsoidal shape induced by their gravitational interaction.
The presence in this system of a third body with a minimum mass of 2.21 has been proposed; however, it should give a significant contribution to the light emitted by the system, and has not been detected yet. A possible solution is for two unseen, but less massive and luminous, stars orbiting close to each other.
Variability.
The orbital plane of the two stars is aligned to our line of sight, so each component eclipses the other when passing in front of it. In AD Andromedae this cycle repeats with a period 20 minutes less than one day.
A cyclic variation of 14.3 years in the orbital period of this binary system has been reported, and this could be an effect of another body orbiting in this system.


VW Leonis Minoris

VW Leo Minoris is a tight quadruple star system, located in the constellation of Leo Minor. With a peak combined apparent visual magnitude of 8.07, it is too faint to be seen with the naked eye. Parallax measurements give a distance estimate of approximately 360 light years from the Sun, and it is drifting further away with a radial velocity of +5 km/s.
Hierarchy of orbits
This system was found to be variable using observations with the Hipparcos satellite. It is classified as an A-type W Ursae Majoris eclipsing binary, where the two stars share a common envelope. The eclipse of the primary causes the magnitude of the system to drop to 8.45. These components (1 & 2) have an orbital period of and the orbital plane has an inclination of 72.4° to the line of sight from the Earth. They have a combined stellar classification of F2V, matching an F-type main sequence star.
In 2006 an additional, detached binary component was discovered, making this a quadruple star system. This binary has an orbital period of 7.93 days, a mild eccentricity (ovalness) of 0.04, and it shows an apsidal precession with a period of . The components (3 & 4) have a combined stellar class of G2V, showing a match with a G-type main-sequence star.
The two binaries (1–2 & 3–4) orbit each other with a period of 355 days and an eccentricity of 0.1. The plane of their orbit is close to coplanar (within 5°) with the orbital plane of the detached binary. This outer orbit appears stable, suggesting there is no additional outlying component to this system. The nearby ninth magnitude star HD 95606 (HIP 53969) shares a common proper motion with this system and may be loosely gravitationally bound. They likely all formed in the same protostellar cloud.


Tau Pegasi

Tau Pegasi (τ Pegasi, abbreviated Tau Peg, τ Peg), formally named Salm (a homophone with the planet Samh), is a 4.6 magnitude star in the constellation of Pegasus.
Nomenclature.
"τ Pegasi" (Latinised to "Tau Pegasi") is the star's Bayer designation.
The star bore the traditional names "Salm", "Kerb" (or "El Khereb") and "Markab" (often spelled "Markeb"), a name shared with Alpha Pegasi, k Puppis and Kappa Velorum. 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 "Salm" for this star and "Markeb" for the component Kappa Velorum A, both on 5 September 2017. "Markab" had previously been approved for Alpha Pegasi on 30 June 2016. All three are now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Resting Palace", refers to an asterism consisting of Tau Pegasi, Lambda Pegasi, Mu Pegasi, Omicron Pegasi, Eta Pegasi and Nu Pegasi. Consequently, the Chinese name for Tau Pegasi itself is (), "the Fifth Star of Resting Palace".
Properties.
Tau Pegasi belongs to spectral class A5 Vp, making it an A-type main-sequence star.
This is a Delta Scuti variable star with a pulsation period of 0.94 hours. It is rotating rapidly with a projected rotational velocity of 150 km s−1. Tau Pegasi is radiating nearly 30 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 7,762 K.


Kepler-27

Kepler-27 is a star in the northern constellation of Cygnus, the swan. It is located at the celestial coordinates: Right Ascension , Declination . With an apparent visual magnitude of 15.855, this star is too faint to be seen with the naked eye.
Planetary system.
The planetary system of Kepler-27 comprising two small gas giants on eccentric orbits was discovered in late 2011. The planets Kepler-27 b and Kepler-27 c equilibrium temperatures are 610 K and 481 K, correspondingly.


GSC 03089-00929

GSC 03089-00929 is a magnitude 12 star located approximately 760 light-years away in the constellation of Hercules. This star is a G type main sequence star that is similar to but slightly cooler than our sun.
This star is identified in SIMBAD as a variable star per the 1SWASP survey.
The star GSC 03089-00929 is named Pipoltr. The name was selected in the NameExoWorlds campaign by Liechtenstein, during the 100th anniversary of the IAU. In the local dialect of Triesenberg, Pipoltr is a bright and visible butterfly.
Planetary system.
In 2007 the TrES program found exoplanet TrES-3b orbiting this star by using the transit method.
The transit timing variation analysis did not reveal any additional planets in the system as of 2020.


55 Persei

55 Persei is a single, blue-white hued star in the northern constellation Perseus. It is faintly visible to the naked eye under good seeing conditions, having an apparent visual magnitude of 5.73. Based upon an annual parallax shift of as seen from Earth's orbit, the star is located about 380 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction of 0.39 due to interstellar dust.
This is a B-type main-sequence star with a stellar classification of B8 V; a massive star that is generating energy through hydrogen fusion at its core. It has 3.44 times the mass of the Sun and about 3 times the Sun's radius. The star is about 197 million years old and is spinning rapidly with a projected rotational velocity of 288 km/s. It is radiating roughly 193 times the Sun's luminosity from its photosphere at an effective temperature of 12,246 K.


Q Puppis

The Bayer designations q Puppis and Q Puppis are distinct. Due to , both designations link here. For the star


RBC EXT8

RBC EXT8 is a globular cluster in the galaxy Messier 31, 27 kpc from the galaxy center. The spectral lines reveal levels of iron 800 times lower than our sun. Its position is right ascension 00h53m14s.53, declination +41°33′24′′. (J2000 equinox) according to the Revised Bologna Catalogue (10). Its magnitude is 15.79, and 15.5" across.


Iota Centauri

Iota Centauri, Latinized from ι Centauri, is a star in the southern constellation of Centaurus. Based upon parallax measurements, it lies at a distance of approximately from Earth. Iota Centauri has an apparent visual magnitude of +2.73, making it easily visible to the naked eye.
In Chinese, (), meaning "Pillars", refers to an asterism consisting of ι Centauri, υ2 Centauri, υ1 Centauri, a Centauri, ψ Centauri, 4 Centauri, 3 Centauri and 1 Centauri. Consequently, the Chinese name for ι Centauri itself is (, .)
The spectrum of ι Centauri matches a stellar classification of A2 V. It is an A-type main sequence star that is generating energy by the nuclear fusion of hydrogen in its core region. This energy is being radiated from the outer envelope of the star at an effective temperature of 8,600 K, giving the star a white hue. It has about 2.5 times the Sun's mass and is roughly 350 million years old. The abundance of elements other than hydrogen and helium, what astronomers term the metallicity, is only 35% of the abundance in the Sun. A weak magnetic field has been tentatively identified with a strength of .
This star has an excess emission of infrared indicating it is surrounded by a circumstellar disk of dust, known as a debris disk. The disk is located within an orbital radius of six Astronomical Units from the star. The dust is unusually luminous for a star this age, suggesting that some process may have recently increased the amount of debris, such as collisions between planetesimals. Alternatively, the planetesimals in this system may have unusual physical properties. As of 2011, a search for planets in this system has thus far been unsuccessful.
Iota Centauri appears to belong to the stellar kinematic group known as IC 2391. This is a group of around 16 co-moving stars that most likely originated in the same molecular cloud at least 45 million years ago.


HD 97658

HD 97658 is a star 70 light years away in the constellation of Leo. The star is slightly too dim to be seen with the naked eye, though almost any additional equipment will allow it to be seen. The star itself is a metal-poor early K-dwarf that is somewhat older than the sun.
Planetary system.
On November 1, 2010, a super-Earth was announced orbiting the star along with Gliese 785 b as part of the NASA-UC Eta-Earth program. The planet orbits in just under 9.5 days and was originally thought to have a minimum mass of 8.2 ± 1.2 M⊕. Spurred by the possibility of transits, additional data was acquired for less than a year which found a lower mass for the star and hence reduced the minimum mass of the planet to 6.4 ± 0.7 M⊕, and improved certainty on the time of possible transit. Transits of the planet were apparently detected and announced on September 12, 2011; this would make HD 97658 the second-to-brightest star with a transiting planet after 55 Cancri and indicating a low-density planet like Gliese 1214 b. However, the occurrence of transits was quietly retracted on April 11, 2012, and three days later it was announced that observations by the MOST space telescope could not confirm transits. Transits of radii larger than 1.87 R⊕ were ruled out.
Further transit measurements were taken in April 2012 and were confirmed with transit readings made in the following year, March and April 2013. It was determined that HD 97658 b had a diameter 2.34 times that of Earth. Using a radial velocity mass of 7.86 M⊕ and the radius measured from the transits taken in 2012 and 2013 and in early 2014, the density of the planet was calculated as 3.44 g cm−3. It is likely therefore that the super-Earth exoplanet HD 97658 b has a large rocky core covered with a thick layer of volatiles, either a deep ocean of water or a thick atmosphere possibly made up of a mixture of helium and hydrogen. The gravity on this exoplanet's surface is about 1.6 times greater than that of Earth's.
The planetary transmission spectrum of HD 97658 b taken in 2020 have revealed presence of clouds up to millibar pressure. Although no conclusion can be made on atmosphere composition, best model fitting is obtained with hydrogen-helium envelope with carbon monoxide and methane admixture. No helium was detected at HD 97658 b in 2020 though.


Chi2 Hydrae

Chi2 Hydrae, Latinised from χ2 Hydrae, is a binary star system in the equatorial constellation of Hydra. Based upon an annual parallax shift of 4.6 mas as seen from Earth, it is located roughly 710 light years from the Sun. It is visible to the naked eye with a combined apparent visual magnitude of 5.71.
This is a detached eclipsing binary star system with an orbital period of 2.27 days and an essentially circular orbit having a measured eccentricity of 0.00. The eclipse of the primary by the secondary component reduces the visual magnitude of the system by 0.29, while the eclipse of the secondary diminishes the magnitude by 0.27.
The primary, component A, is a magnitude 5.85 B-type star with a stellar classification of B8 III-IVe, suggesting it may be part way along the path of evolving into a giant star from a subgiant. It has about 3.6 times the mass of the Sun and 4.4 times the Sun's radius, although it may be tidally deformed since its radius is 86% of the Roche radius. With an estimated age of 158 million years, it has a projected rotational velocity of 112 km/s.
Component B is a magnitude 7.57 B-type main sequence star with a class of B8.5 V. It has 2.6 times the Sun's mass and 2.16 times the radius of the Sun. The star is filling 60% of its Roche radius.


NGC 3576

NGC 3576 is a bright emission nebula in the Sagittarius arm of the galaxy a few thousand light-years away from the Eta Carinae nebula. It is also approximately 100 light years across and 9000 light-years away from Earth. This nebula even received six different classification numbers. Currently, astronomers call the entire nebula NGC 3576. A popular nickname is "The Statue of Liberty Nebula" because of the distinctive shape in the middle of the nebula. Discovered by John Frederick William Herschel on 16 March 1834. The name was first suggested in 2009 by Dr. Steve Mazlin, a member of Star Shadows Remote Observatory (SSRO). Within the nebula, episodes of star formation are thought to contribute to the complex and suggestive shapes. Powerful winds from the nebula's embedded, young, massive stars shape the looping filaments.


NGC 3550

NGC 3550 is a lenticular galaxy in the constellation Ursa Major. It was discovered on April 11, 1785 by William Herschel. It is one of the brightest galaxies of the Abell 1185 galaxy cluster.


NGC 276

NGC 276 is a barred spiral galaxy located approximately 626 million light-years from the Solar System in the constellation Cetus. It was discovered in 1886 by Frank Muller and was later also observed by DeLisle Stewart.
John Dreyer, creator of the New General Catalogue describes the object as "extremely faint, pretty small, extended 265°, 11 magnitude star 3 arcmin to north". The galaxy's right ascension was later corrected in the Index Catalogue using the observation data by Stewart.


20 Canum Venaticorum

20 Canum Venaticorum is a single variable star in the northern constellation of Canes Venatici, located 238 light years from the Sun. This object has the variable star designation AO Canum Venaticorum; "20 Canum Venaticorum "is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star with a baseline apparent visual magnitude of +4.72. The star is moving further from the Earth with a heliocentric radial velocity of +9 km/s. Eggen (1971) listed this star as a member of the Hyades Stream.
This star has a stellar classification of , which indicates the hydrogen line matches an A-type bright giant but the metal lines are closer to an F-type star. However, it does not appear to be an Am star as the Calcium K line is normal. Earlier, Morgan and Abt (1972) assigned it a giant star class of F3 III. It is classified as a Delta Scuti type variable star with a single radial pulsation mode providing the best fit to the observed variation. Its brightness varies from magnitude +4.70 to +4.75 with a period of 2.92 hours.
20 Canum Venaticorum is 750 million years old with 2.43 times the mass of the Sun and 4 time the Sun's radius. It is radiating 63 times the Sun's luminosity from its photosphere at an effective temperature of 7,314 K.


NGC 5929

NGC 5929 is a Seyfert galaxy in the constellation Boötes. The pair of galaxies, NGC 5929 and NGC 5930, are interacting.


NGC 782

NGC 782 is a barred spiral galaxy located in the constellation Eridanus about 160 million light-years from the Milky Way. It was discovered by British astronomer John Herschel in 1834.


NGC 5749

NGC 5749 is an open cluster in the constellation Lupus.


32 Cygni

32 Cygni (32 Cyg, Omicron2 Cyg, ο2 Cyg) is the Flamsteed designation for a binary star system in the Cygnus constellation. It is a 4th magnitude star, which can be seen with the naked eye under suitably dark skies. Parallax measurements give an estimated distance of 1,100 light-years (320 parsecs) from the Earth. However, Schröder et al. (2007) suggest the actual value, after correcting for Malmquist bias, may be closer to 1,174 light-years (360 parsecs). Although it is a spectrsocopic binary with components that cannot be separated visually, it has two entries in the Henry Draper Catalogue, with identical magnitudes and positions, but showing the spectral types of the two components.
The Bayer letter ο has been variously applied to two or three of the stars 30, 31, and 32 Cygni. 32 Cygni has been designated as either ο2 or ο3 Cygni. For clarity, it is preferred to use the Flamsteed designation 32 Cygni rather than one of the Bayer designations.
The primary component in this system, 32 Cygni A, has a stellar classification of K5 Iab, indicating that it is a supergiant star. Its effective temperature of 3,840 K lies in the range for K-type stars, giving it an orange hue. This star has more four than times the mass of the Sun and the outer envelope has expanded to about 184 times the Sun's radius. It is radiating 6,600 times the luminosity of the Sun.
The companion star, 32 Cygni B, is smaller than the primary, with four times the Sun's mass and three times the Sun's radius. It has a much higher effective temperature of 16,200 K and is radiating over 300 times the Sun's luminosity. This star has the blue-white hue of a B7 star main sequence star.
The two stars form an eclipsing binary system (variable star designation: V1488 Cyg) similar to Algol. The orbital plane of the two stars is nearly aligned with the line of sight from the Earth, so that the giant star eclipses the secondary component once per orbit. During an eclipse, emission lines can be seen in the spectrum of this system. These originate in the stellar wind escaping from the giant star. In a volume around the B star, this wind becomes ionized, resulting in a circumstellar H II region. The giant star is losing mass at the rate of times the mass of the Sun per year, or the equivalent of the Sun's mass every 77 million years.
The Washington Double Star Catalog and Catalog of Components of Double and Multiple Stars both list a visual companion 208" distant. This star is the 8th magnitude A class HD 192933.


G 9-38

G 9-38, also known as EI Cancri and GJ 1116, is a binary star system consisting of two M-type stars. At 16.7 light-years from the Sun, the system is relatively nearby. The system has a very high stellar flare activity, with average five flares per hour.
In 2015, the search for third star in the system has yielded inconclusive results.


Gamma2 Sagittarii

Gamma² Sagittarii (γ² Sagittarii, abbreviated Gamma² Sgr, γ² Sgr), formally named Alnasl , is a 3rd-magnitude star in the zodiac constellation of Sagittarius. The location of this star forms the tip of the arrow in the bow of Sagittarius the Centaur. Based on parallax measurements obtained during the Hipparcos mission, it is approximately from the Sun. It has an apparent visual magnitude of +2.98, making it the seventh-brightest star in the constellation.
It forms part of a double star along with a fainter optical companion designated Gamma¹ Sagittarii located about 50 arcminutes north of this star. The latter is a magnitude 4.7 Cepheid variable star that also has the variable star designation W Sagittarii.
Nomenclature.
"γ² Sagittarii" (Latinised to "Gamma² Sagittarii") is the star's Bayer designation.
It bore the traditional names "Alnasl" (alternatively "Nasl", "El Nasl"), "Nushaba" ("Nash") and "Awal al Warida". "Alnasl" is derived from the Arabic النصل "al-naşl" and "Nushaba" is derived from the Arabic "Zujj al-Nashshaba", both meaning "arrowhead". In the catalogue of stars in the calendarium of Al Achsasi al Mouakket, this star was designated "Awal al Waridah", meaning "first [star] of the [ostrich] going down to the water", from the Arabic النعامة الواردة "Al Naʽāma al Wārida", the name of the asterism consisting of this star, Delta Sagittarii, Epsilon Sagittarii and Eta Sagittarii. This ostrich was thought of as going down to the river (the Milky Way) to drink, and another ostrich (σ, φ, τ, and ζ, "al Sadira") was thought of as coming back up.
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 "Alnasl" for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
Gamma² Sagittarii, together with Delta Sagittarii, Epsilon Sagittarii, Zeta Sagittarii, Lambda Sagittarii, Sigma Sagittarii, Tau Sagittarii and Phi Sagittarii, comprise the Teapot asterism.
Together with Delta Sagittarii and Epsilon Sagittarii, Gamma Sagittarii formed the Akkadian "Sin-nun‑tu", or "Si-nu-nu‑tum" 'the Swallow'.
In Chinese, (), meaning "Winnowing Basket", refers to an asterism consisting of Gamma Sagittarii, Delta Sagittarii, Epsilon Sagittarii and Eta Sagittarii. Consequently, Gamma Sagittarii itself is known as (, .)
Properties.
A stellar classification of K1 III reveals that this is a giant star, having expanded to an estimated 12 times the Sun's radius. This means it has exhausted the hydrogen in its core and evolved away from the main sequence. The abundance of elements other than hydrogen and helium in this star, what astronomers term the star's metallicity, is lower than in the Sun. Gamma² Sagittarii has an effective temperature of 4,760 K, compared to 5,778 K for the Sun. It is this lower temperature that gives Gamma² Sagittarii the orange hue that is a characteristic of K-type stars.


Theta Lupi

Theta Lupi, Latinized from θ Lupi, is a solitary star in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.22. (The planetary nebula NGC 6072 lies 1.4° to the east-northeast.) Based upon an annual parallax shift of 7.87 mas as seen from Earth, it is located roughly 410 light years away from the Sun. Relative to its neighbors, this star has a peculiar velocity of . It is a member of the nearby Sco OB2 association.
This is a B-type main sequence star with a stellar classification of B2.5 Vn, where the 'n' suffix indicates nebulous lines due to spin. It is rotating rapidly with a projected rotational velocity of 331 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 15% larger than the polar radius. The star has an estimated 6.5 times the mass of the Sun and around 4.5 times the Sun's radius. With an age of just 24.6 million years, it is radiating 792 times the solar luminosity from its outer atmosphere at an effective temperature of 15,395 K.


Sigma Aurigae

Sigma Aurigae, Latinized from σ Aurigae, is a giant star in the northern constellation of Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of 4.99. With an annual parallax shift of 6.21 mas, it is approximately distant from the Earth. This is an evolved giant star with a stellar classification of K4 III.
Sigma Aurigae has a 12th magnitude companion at an angular separation of 8 arcseconds, as well as two fainter companions at 28 and 35" respectively. All are background objects, stars much further away than Sigma itself.


22 Aurigae

22 Aurigae is a star located 537 light years away from the Sun in the northern constellation Auriga. It is just bright enough to be barely visible to the naked eye under good viewing conditions, appearing as a blue-white hued star with an apparent visual magnitude of 6.45. At the distance of this object, the brightness is diminished by an extinction of 0.57 due to interstellar dust. The star is moving further from the Earth with a heliocentric radial velocity of +10 km/s, and it is a member of the Taurion OB association, located between Orion and Taurus.
This object is a B-type main-sequence star with a stellar classification of B9 Vs. The 's' notation indicates the spectrum appears "sharp"-lined, due to its relatively moderate projected rotational velocity of 66 km/s. It has 2.9 times the mass of the Sun and about 3.1 times the Sun's radius. The star is radiating 90 times the luminosity of the Sun from its photosphere at an effective temperature of 10,764 K.


Nu Eridani

Nu Eridani (ν Eri) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.93. The distance to this star is roughly 520 light years, based upon an annual parallax shift of 0.00625 arcseconds. If the star were from the Sun, it would be the brightest star in the night sky with an apparent magnitude of −2.84. (Currently, the brightest star is Sirius at magnitude −1.46.)
This is a B-type subgiant star with a stellar classification of B1.5 IV. It is a hybrid pulsator variable, lying as it does on the overlapping instability strips for Beta Cephei variables and slowly pulsating B-type stars. The star shows at least fourteen pulsations frequencies, with nine that also display radial velocity variations. It has about nine times the mass of the Sun and six times the Sun's radius. Nu Eridani shines with 7,943 times the solar luminosity from its outer atmosphere at an effective temperature of 22,000 K.


CM Draconis

CM Draconis (GJ 630.1A) is an eclipsing binary system approximately 47 light-years away in the constellation of Draco (the Dragon). The system consists of two nearly identical red dwarf stars located in the constellation Draco. The two stars orbit each other with a period of 1.27 days with a separation of 2.7 million kilometres (0.018 AU). Along with two stars in the triple system KOI 126, the stars in CM Draconis are the lightest stars with precisely measured masses and radii. Consequently, the system plays an important role in testing stellar structure models for very low mass stars. These comparisons find that models underpredict the stellar radii by approximately 5%. This is attributed to consequences of the stars' strong magnetic activity.
According to the system's entry in the Combined General Catalogue of Variable Stars, at least one of the components is a flare star and at least one is a BY Draconis variable. The white dwarf star GJ 630.1B, located 25.7 arcseconds away shares the same proper motion as the CM Draconis stars and is thus a true companion star of the system. Given the system's distance of 47 light years, this corresponds to a separation of at least 370 astronomical units between CM Draconis and GJ 630.1B.
Possible planetary system.
The system was the subject of a dedicated search for transiting extrasolar planets in orbit around the binary from 1994–1999. In the end, the existence of all of the transiting planet candidates suggested by the project was ruled out.
Based on variations in the timing of the system's eclipses, it has been suggested that there may be an object in a circumbinary orbit around the two red dwarf stars. In 2000, it was proposed that a Jovian planet is orbiting the system with a period of 750–1050 days. A later analysis of timing variations did not confirm this proposed planet and instead suggested that there was a Jovian planet in an 18.5-year orbit, or a more massive object further out. This analysis was itself not supported by a 2009 study that found the eclipse timings were indistinguishable from linear, though the binary stars do have a small eccentricity that may indicate that they are being perturbed by an orbiting body that prevents the orbit from being fully circularised by tidal effects. A massive planet or brown dwarf on an orbit of 50–200 days would fulfil the observational criteria: the requirement for dynamical stability, the constraints from the lack of observed timing variations and the requirement that the object can maintain the eccentricity of the binary stars.


List of stars in Carina

This is the list of notable stars in the constellation Carina, sorted by decreasing brightness.
This constellation's Bayer designations (Greek-letter star names) were given while it was still considered part of the constellation of Argo Navis. After Argo Navis was broken up into Carina, Vela, and Puppis, these Greek-letter designations were kept, so that Carina does not have a full complement of Greek-letter designations. For example, since Argo Navis's gamma star went to Vela, there is no Gamma Carinae.


39 Arietis

39 Arietis (abbreviated 39 Ari), officially named Lilii Borea , is a star in the northern constellation of Aries. It is visible to the naked eye with an apparent visual magnitude of +4.5. The distance to this star, as determined from an annual parallax shift of 19.01 mas, is approximately .
Nomenclature.
"39 Arietis" is the star's Flamsteed designation.
This star was described as "Lilii Borea" by Nicolas-Louis de Lacaille in 1757,
as a star of the now-defunct constellation of Lilium (the Lily). The words are simply the Latin phrase "Līliī Boreā" 'in the north of Lilium'. "Līliī Austrīnā" 'in the south of Lilium' was 41 Arietis.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name "Lilii Borea" for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Stomach", refers to an asterism consisting of 39 Arietis, 35 Arietis and 41 Arietis. Consequently, the Chinese name for 39 Arietis itself is (, ).
Properties.
39 Arietis is a giant star with a stellar classification of K1.5 III. It is currently at an evolutionary stage known as the red clump, indicating that it is generating energy through the fusion of helium at its core. It has 1.6 times the mass of the Sun, but its outer envelope has expanded to around 11 times the Sun's radius. It shines with 56 times the luminosity of the Sun. This energy is being radiated into outer space from its outer atmosphere at an effective temperature of 4,603 K, giving it the cool orange-hued glow of a K-type star.
External links.


36 Serpentis

36 Serpentis is a binary star system in the equatorial constellation of Serpens. It has the Bayer designation b Serpentis, while "36 Serpentis" is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with a combined apparent visual magnitude of 5.09. It is located 162 light years away from the Sun based on parallax, and is moving closer with a radial velocity of −8 km/s.
This is a spectroscopic binary star system with a long orbital period of 52.8 years and a high eccentricity of 0.83. The combined mass of the pair is . Gray et al. (2017) found a merged stellar classification of A2IV-Vn for this system, while Cowley et al. matched it with a class of A3Vn, where the 'n' indicates "nebulous" lines caused by rapid rotation.
The primary component is a Lambda Boötis star, meaning that it has solar-like amounts of carbon, nitrogen, and oxygen, while containing very low amounts of iron peak elements. It is an A7 class main sequence star of visual magnitude 5.2 that is spinning rapidly, showing a projected rotational velocity of 229. The star is 723 million years old with around double the mass of the Sun. It is radiating 19 times the Sun's luminosity from its photosphere at an effective temperature of 8,246 K.
The cooler secondary component, a G0 star, is the source for the X-ray emission that has been detected coming from this system. It has a visual magnitude of 7.8.


HD 220466

HD 220466 is a F-type subgiant or main sequence star in the constellation Aquarius. It has apparent magnitude 6.47 and is about 200 light-years away. In 1913, an apparent visual companion of apparent magnitude 10.3 was observed 1.9 arcseconds away from the star, but it is doubtful whether it exists.


Lambda Lyrae

λ Lyrae, Latinized from Lambda Lyrae, is a suspected binary star system in the northern constellation of Lyra. It is an orange-hued point of light that is dimly visible to the naked eye with an apparent visual magnitude of 4.94. The system is located approximately 1,300 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −17.7 km/s.
The visible component is an aging giant star with a stellar classification of K2.5III:Ba0.5 and an estimated age of around 58 million years. The suffix notation indicates this is a mild barium star and hence it may have a white dwarf companion, while the colon indicates there is some uncertainty about the class. Having exhausted the supply of hydrogen at its core, it has cooled and expanded off the main sequence, and now has 102 times the radius of the Sun. The star has six times the mass of the Sun and is radiating over 3,000 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,253 K.


94 Piscium

94 Piscium is a single star in the zodiac constellation Pisces, located 305 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.495. The object is moving closer to the Earth with a heliocentric radial velocity of −43 km/s. It is a possible member of the Wolf 630 moving group.
This is an evolved K-type giant star with a stellar classification of K1 III. It is a red clump giant, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 4.1 billion years old with 1.34 times the mass of the Sun and 13 times the Sun's radius. It is radiating 69 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,665 K.


NGC 378

NGC 378 is a barred spiral galaxy located in the constellation Sculptor. It was discovered on September 28, 1834 by John Herschel.


NGC 6760

NGC 6760 is a globular cluster in the constellation Aquila. It may have contributed to the formation of the open cluster Ruprecht 127 during NGC 6760's passage through the galactic disk 71 million years ago.
At least two millisecond pulsars have been found in NGC 6760.


Phi Cancri

The Bayer designation Phi Cancri (φ Cnc / φ Cancri) is shared by a star and star system, in the constellation Cancer:
They are separated by 0.96° on the sky.


NGC 2803

NGC 2803, also known as PCG 26181, is an elliptical or lenticular galaxy in the zodiac constellation Cancer. It was discovered March 21, 1784, by William Herschel. It is interacting with NGC 2802.


U Aquilae

U Aquilae is a binary star system in the constellation Aquila, Located approximately away from Earth.
The primary star (component A) is a yellow supergiant with a radius of and a luminosity of . The secondary (component B) is a blue main-sequence star, twice the mass of the sun and around thirty times more luminous. It is hotter than the primary star at 9,300 K, but much smaller and fainter. The two stars orbit every five years and their separation varies from five to seven astronomical units in a mildly eccentric orbit.
u Aql A is a classical Cepheid variable star ranging between magnitudes 6.08 and 6.86 over a period of 7.02 days. It is an evolved star which has exhausted its core hydrogen and is now fusing helium into carbon.


SX Centauri

SX Centauri is a variable star in the constellation Centaurus. An RV Tauri variable, its light curve alternates between deep and shallow minima, varying its apparent magnitude from 9.1 to 12.4. From the period-luminosity relationship, it is estimated to be around 1.6 kpc (5200 light-years) from Earth. Gaia Data Release 2 gives a parallax of 0.2175 mas, corresponding to distance of about .
RV Tauri variables like SX Centauri are supergiant pulsating stars and a subtype of the population II Cepheids. They are stars that have already passed the asymptotic giant branch (AGB) and are in the last stage of their evolution before becoming a planetary nebula. This transition phase is very fast, and may last for less than a thousand years. SX Centauri is in the beginning of this process and is estimated to be leaving the AGB right now, or to have left the AGB a few decades ago. Its pulsations are radial in nature and have a period of about 32.9 days (from deep minimum to deep minimum), causing the effective temperature of the star to vary between 5,000 and 6,500 K and the radius between 21 and 29 solar radii. The radius seems to have the same value in both the primary and secondary minima, while the temperature shows a 500 K variation between minima.
The spectrum of SX Centauri shows infrared excess, indicating the presence of a circumstellar disk of hot dust around the star. interferometric observations constrained the diameter of the disk to less than 11 arcseconds (18 AU at the star's distance), indicating a very compact system. The infrared emission is consistent with a hotter component (715 K) corresponding to 4% of the dust, and a colder one (244 K) corresponding to 96% of the dust. This material is composed mainly of amorphous carbon and graphite (83%), with the remainder being pyroxene and olivine. The disk is related to a depletion of refractory elements (with high condensation temperature) in the star's photosphere; this is caused by separation of gas from dust rich in refractories, followed by accretion of the gas by the star.
SX Centauri is a spectroscopic binary, having a companion star with an orbital period of 592 days and an orbital eccentricity of 0.16. This companion has a mass estimated between 1.4 and 1.9 solar masses and is probably an unevolved main sequence star. The system must have interacted in the past when the primary was a red giant, which is likely related to the formation of disk. All RV Tauri stars with dust disks are believed to be part of a binary system.
Slow periodic variations in the mean brightness of SX Centauri have been detected, leading the star to be classified as an RV Tauri star of the photometric class b (RVb). The period of this variation is approximately equal to the orbital period of the system. This phenomenon can be explained as variation of the circumstellar extinction during the orbital motion of the disk.


54 Arietis

54 Arietis is a star in the northern zodiac constellation of Aries. "54 Arietis" is the Flamsteed designation. It is a challenge to view with the naked eye even under good viewing conditions, having an apparent visual magnitude of 6.27. Based upon an annual parallax shift of , it is located approximately distant from Earth, and it is drifting further away with a radial velocity of +44 km/s. The brightness of the star is diminished by 0.15 in magnitude from extinction caused by interstellar gas and dust. The star is positioned near the ecliptic and thus is subject to lunar occultations.
This is an aging red giant star with a stellar classification of M0 III that is currently evolving along the asymptotic giant branch. Having exhausted the supply of hydrogen at its core, the star has expanded to 41 times the Sun's radius. It varies slightly in brightness, with a periodicity of 6.2 days and an amplitude change of 0.0096 in magnitude. On average it is radiating 387 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,013 K.


OJ 287

OJ 287 is a BL Lac object located 3.5 billion light-years away that has produced quasi-periodic optical outbursts going back approximately 120 years, as first apparent on photographic plates from 1891. Seen on photographic plates since at least 1887, it was first detected at radio wavelengths during the course of the Ohio Sky Survey. It is a supermassive black hole binary. The intrinsic brightness of the flashes corresponds to over a trillion times the Sun's luminosity, greater than the entire Milky Way galaxy's light output.
Characteristics.
Its central supermassive black hole is among the largest known, with a mass of 18.35 billion solar masses, more than six times the value calculated for the previous largest object. Its Schwarzschild radius is ~362 AU, about 12 and 0.75 times the semimajor axes of the orbits of Neptune and dwarf planet Sedna, respectively.
The optical light curve shows that OJ 287 has a periodic variation of 11–12 years with a narrow double peak at maximum brightness. This kind of variation suggests that it is a binary supermassive black hole. The double-burst variability is thought to result from the smaller black hole punching through the accretion disc of the larger black hole twice in every 12 years.
The smaller supermassive black hole with a mass of "only" 150 million orbits the larger one with an observed orbital period of ~12 years and a calculated eccentricity of ~0.65. The maximum brightness is obtained when the minor component moves through the accretion disk of the supermassive component at perinigricon. The perinigricon and aponigricon of its orbit are ~3,250 and ~17,500 AU, or about 9 and 48 times the primary's Schwarzschild radius; the latter is also ~0.275 light-year and ~0.085 parsec.
The mass was calculated in 2008 by a team led by Mauri Valtonen of Tuorla Observatory in Finland. The timing of these outbursts allows the precession of the companion's elliptical orbit to be measured (39° per orbit), which allows the mass of the central black hole to be calculated using Einstein's principles of general relativity (see Kepler problem in general relativity). The timings also provide a test of the black hole no-hair theorem, which so far is consistent with the results.
In order to reproduce all the known outbursts, the rotation of the primary black hole has to be 38% of the maximum allowed rotation for a Kerr black hole.
The companion's orbit is decaying via the emission of gravitational radiation and it is expected to merge with the central black hole within approximately 10,000 years.


NGC 777

NGC 777 is an elliptical galaxy in the constellation of Triangulum. It was discovered by William Herschel on September 12, 1784.


Theta Coronae Australis

Theta Coronae Australis, Latinized from θ Coronae Australis, is a star located in the constellation Corona Australis. Theta Coronae Australis is also known as HR 6951, and HD 170845. Parallax measurements by Hipparcos put it at a distance of roughly 560 light-years, or 171 parsecs, away from the Solar System.
Theta Coronae Australis is a G-type giant star that is radiating 497 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,794 K. It has an apparent visual magnitude of 4.64, and is about 11 times wider than the Sun. Theta Coronae Australis has an unusually high rate of rotation for an evolved star of this type, showing a projected rotational velocity of 11.8 km/s. One possible explanation is that it may have engulfed a nearby giant planet, such as a hot Jupiter.


V4998 Sagittarii

V4998 Sagittarii is a luminous blue variable star (LBV) in the constellation of Sagittarius. Located some 25,000 light years away, the star is positioned about 7 pc (23 ly) away from a starburst cluster known as the Quintuplet cluster. It has an ejection nebula measuring over 0.8 pc in diameter, formed 5000-10,000 years ago through large eruptions. The star has a large mass comparable to the Pistol star and a luminosity of around 4,000,000 times the Sun (). This places the star as one of the most massive and luminous stars known.
Observational history.
The star was first discovered in a 1993 survey that searched for bright near-infrared sources within 0.55°2 of the galactic centre. The survey used 1–20 micron photometry and used a two channel InSb detector on the 1 meter ANU telescope in Australia. 50 objects were targeted and most of them had bolometric magnitudes below -5. The star itself was observed in May 1987. Its position, "JHKLNMQ" magnitudes, right ascension, declination, and silicate absorption were noted. The survey was conducted by Tetsuya Nagata, A. R. Hyland, S. M. Straw, Shuji Sato, and Kimiaki Kawara. The survey named the star NHS93 22; NHS standing for the three leading scientists in the survey (Nagata, Hyland, and Straw), 93 signifying the date of discovery, and 22 indicating that it was the 22nd star observed.
The next observation was made by the 2MASS survey, which took place in 1997-2001. The star was designated 2MASS J17460562-2851319 and its position, luminosity, and "JHKs" magnitudes were catalogued. After that, the star was observed in a 2001 survey called the "Study of Long Period Variables stars near the Galactic Centre". The survey named the star GMC2001 10-1, GMC standing for Glass, Matsumoto, and Carter. It was observed by the Infrared Array Camera on board the Spitzer Space Telescope in a 2008 survey covering 2.0 by 1.4 degrees (280 by 210 pc) and was given the name SSTGC 595621. It was also observed by a 2009 near-infrared survey that targeted the Galactic Centre. The star was designated MKN2009 in that survey, MKN standing for the three leading scientists (Matsunaga, Kawadu, and Nishiyama) and 2009 specifying the date of the survey.
A narrowband imaging survey of the Galactic centre region conducted by the Hubble Space Telescope (HST) Near Infrared Camera and Multi Object Spectrometer (NICMOS) revealed LBV G0.120-0.048 as a strong source of Paschen-alpha (Paschen-α) emission which exceeded that of the Pistol star. Therefore the star was selected for spectroscopy. The survey, which was conducted in 2010, confirmed that the star was a luminous blue variable and the star was designated LBV G0.120-0.048, LBV meaning luminous blue variable and G0.120-0.048 standing for its Galactic coordinates. It was also found through the use of Pα imaging that the star had a large ejection nebula with a diameter over 0.8 pc which was ejected by it 5000-10,000 years ago through large eruptions. The star's spectrum was studied and it was found that the spectrum was similar to the Pistol star so a mass similar to the Pistol star was assumed. The extinction rates were measured and a luminosity of about was obtained. It also has the designation MMC2010 from a 2010 survey, MMC standing for the three leading scientists of the survey, Mauerhan, Morris, and Cotera. In 2011, a survey led by Dong, Wang, and Cotera reached for stars in the Galactic centre that emitted Paschen-α. The stars targeted were the ones detected from the HST/NICMOS Paschen-α survey of the Galactic Centre. V4998 Sagittarii was one of the stars observed and it was given another designation of DWC2011 92.
In 2014 a group decided to study the LBVs in the Quintuplet cluster. The mass of the star's nebula was measured at . Also measured was the star's effective temperature and it was found to be 12,000 K. The star was designated LBV3 in that survey because it was the third LBV in the Quintuplet cluster.
Characteristics.
V4998 Sgr's high mass compresses its core and accelerates fusion primarily by the CNO cycle which leads to a luminosity of about and a temperature of 12000 K. It boasts a large ejection nebula with a diameter of about 0.8 parsec (2.5 ly) and a mass of . Since comparable nebulae typically last no more than 10,000 years, V4998 Sagittarii is presumed to have undergone a massive eruption 5000-10,000 years ago.
The star is a projected 7 pc (23 ly) away from the Quintuplet starburst cluster, which lies in the direction of the Galactic center. The cluster contains around 100 O-type stars and several Wolf–Rayet stars. There are also two other luminous blue variables beside V4998 Sagittarii: the Pistol star and qF362.
Evolution.
The star's high mass loss rate combined with its eruptions will strip off its hydrogen layers and expose a hot helium core. It will proceed to the Wolf–Rayet sequence. It will eventually start fusing heavy elements in its core, and when it develops a large iron core the star will collapse in on itself and explode as a type Ib or Ic supernovae. Depending on the amount of mass lost before the supernova explosion, the remnant will be a neutron star or black hole. A black hole is predicted for the most massive stars such as this one.


AK Pyxidis

AK Pyxidis is a semiregular variable star located in the constellation Pyxis. It varies between magnitudes 6.09 and 6.51, pulsating to multiple periods simultaneously of 55.5, 57.9, 86.7, 162.9 and 232.6 days. Located around 1228 light-years distant, it shines with a luminosity approximately 1500 times that of the Sun and has a surface temperature of 3410 K.


Mu Piscis Austrini

Mu Piscis Austrini (μ Piscis Austrini) is a solitary, white-hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.49. Based upon an annual parallax shift of 26.7542 mas as seen from the Gaia space telescope, the star is located around 122 ± 2 light years from the Sun.
This star has the spectrum of an A-type subgiant with a stellar classification of A1.5 IVn. It is spinning rapidly with a projected rotational velocity of 308 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 23% larger than the polar radius. An X-ray emission has been detected from this star with a luminosity of . This may be coming from an undiscovered companion, since A-type stars are not expected to be a significant source of X-rays.
Mu Piscis Austrini is moving through the Galaxy at a speed of 20 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,800 and 28,500 light years from the center of the Galaxy. Mu Piscis Austrini came closest to the Sun 1.2 million years ago when it had brightened to magnitude 4.06 from a distance of 111 light years.
Naming.
In Chinese, (), meaning "Celestial Money", refers to an asterism consisting of refers to an asterism consisting of μ Piscis Austrini, 13 Piscis Austrini, θ Piscis Austrini, ι Piscis Austrini and τ Piscis Austrini. Consequently, the Chinese name for μ Piscis Austrini itself is (, .)


Pi Lupi

π Lupi (Latinised to Pi Lupi) is a multiple star system in the southern constellation Lupus. Two components form a wide binary pair with an orbital period of 517 years and a semimajor axis of 1.59″. At least one of the components is a spectroscopic binary. They belong to the Upper Centaurus
Lupus component of the Sco–Cen Complex.


GR 8 (galaxy)

GR 8 (also known as UGC 8091) is a gas-rich dwarf irregular galaxy.
In 1995, Tolstoy et al. estimated its distance (with the Hipparcos correction of 1997 applied) to be approximately from Earth. It is still an open question as to whether or not it is a member of the Local Group. It was discovered at the Lick Observatory using the 20-inch astrograph in either 1946, 1947, or 1951.


NGC 7429

NGC 7429 is an open cluster in the constellation Cepheus. The object was discovered on 29 September 1829 by the British astronomer John Herschel.


X Caeli

X Caeli, or Gamma2 Caeli, is a binary star system in the southern constellation of Caelum. It is barely visible to the naked eye with an apparent visual magnitude of 6.32. based upon an annual parallax shift of , it is located 341 light years from Earth. The system is moving further away with a heliocentric radial velocity of +6 km/s.
The yellow-white hued primary, component A, has an apparent magnitude of +6.32 and stellar classification of F2 IV/V, showing mixed traits of an F-type main-sequence star and a subgiant. It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +6.28 to +6.39 with a period of 3.25 hours. A 2000 observing campaign identified at least six independent pulsation modes for this variation. The companion star, component B, has an apparent magnitude of +9.65 and, as of 2000, is at an angular separation of along a position angle of 183°.


4 Persei

4 Persei is a single star in the northern constellation of Perseus, located around 670 light years away from the Sun. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 5.04 The Bayer designation for this star is g Persei; "4 Persei" is the Flamsteed designation. This object has a peculiar velocity of 26.3 km/s and may be a runaway star.
The stellar classification for 4 Persei is B8 III, matching an aging B-type giant star that has evolved off the main sequence. It is spinning with a projected rotational velocity of 60 km/s and has about 3.2 times the Sun's radius The star is radiating 670 times the luminosity of the Sun from its photosphere at an effective temperature of 12,230 K. 4 Persei is embedded in a small, relatively dense dust cloud, which is resulting in infrared emission from the cold dust.


NGC 5882

NGC 5882 is a small planetary nebula in the southern constellation of Lupus, positioned about 1.5° to the southwest of the star Epsilon Lupi. It was discovered by English astronomer John Herschel on July 2, 1834 from the Cape of Good Hope observatory. John L. E. Dreyer described it as "very small, round, quite sharp". It is located at a distance of approximately from the Sun.
This nebular region consists of the cast-off outer atmosphere of an aging star. It is roughly elliptical in shape with several clumps of ionized material, and is surrounded by a larger region of low-level emission that extends for three times the nominal diameter of the main nebula. The nebula is expanding with an average velocity of . It consists of two shells: the inner shell is elliptical and measures , while the more rapidly expanding outer shell is rounder with a diameter of . The inner shell has what appears to be multiple bubble-like shapes. The clumps in the outer shell may be the result of instabilities.
The elemental abundances of the nebula are very similar to those in the Sun, except for a times two enrichment of nitrogen. The latter suggests that the central star did not go through second dredge-up. The central star has an apparent visual magnitude of 13.43. It shines with 830 times the luminosity of the Sun and has 22.7% of the Sun's radius. It is displaced slightly from the center of symmetry for the nebula.


HD 83953

HD 83953 (I Hydrae) is a single, blue-white hued star in the equatorial constellation of Hydra. It is visible to the naked eye, having an apparent visual magnitude of 4.76. Based upon an annual parallax shift of , the distance to this star is estimated as 500 light years. It is moving further from Earth with a heliocentric radial velocity of +16 km/s.
This is a B-type main-sequence star with a stellar classification of B5 V. It has been known to be a Be star since 1926, when an Hβ emission line was discovered in the stellar spectrum by Mount Wilson Observatory. This energy is coming from a circumstellar envelope of heated gas that has been expelled from the central star and formed a thin orbiting disk. HD 83953 is spinning rapidly with a projected rotational velocity of 315 km/s, giving the star an oblate shape with an equatorial bulge that is 18% larger than the polar radius.
HD 83953 has 4.6 times the mass of the Sun and 4.0 times the Sun's radius. It is radiating 708 times the Sun's luminosity from its photosphere at an effective temperature of 15,000 K.


NGC 5002

NGC 5002 is a Magellanic spiral galaxy in Canes Venatici. It was discovered by Heinrich d'Arrest in 1865. It is also known as MCG 6-29-51, PGC 45728, UGC 8254.
It has an apparent size of 1.7 by 1.0 arcmin.


NGC 3665

NGC 3665 is a lenticular galaxy located in the constellation Ursa Major. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that NGC 3665 is about 85,000 light years across. It was discovered by William Herschel on March 23, 1789.
Characteristics.
NGC 3665 is a lenticular galaxy whose disk is characterised by the presence of a circular dust lane. The galaxy has high molecular gas content, as determined by the detection of CO lines. The molecular gas mass in the galaxy is estimated to be 108.91 . The galaxy has a UV excess that indicates the presence of a young stellar population. The total star formation rate in NGC 3665 is estimated to be 1.7 per year. This rate is less than the one expected based on the molecular gas reservoirs of the galaxy. It has been suggested that the compact yet massive bulge of the galaxy has stabilised the cold gas, and thus suppressed star formation.
The nucleus of the galaxy is active and hosts a low luminosity transition active galactic nucleus (AGN). The most accepted theory for the energy source of AGNs is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 3665 is measured using the rotation of the molecular gas around the nucleus as , or based on the M–sigma relation.
NGC 3665 has been found to emit radio waves. Its emission appears elongated at a position angle perpendicular to the dust lane, with the most luminous region being in the nucleus. The emission extends for more than 5 arcminutes in 610 MHz. In 1.4 GHz, the galaxy has one jet with FRI morphology, that extends for more than 3 kpc. In 5 GHz, emission appears in the nucleus and two jet-like structures. The southeast source has not been resolved, while the northwest extends for 0.7 arcseconds, which corresponds to 120 pc at the distance of NGC 3665. The radio emission is likely associated with a low luminosity AGN.
Supernova.
One supernova has been detected in NGC 3665, SN 2002hl. It was discovered by T. Boles in unfiltered CCD images taken on November 5, 2002 with a 0.35-m reflector, as part of the U.K. Nova/Supernova Patrol. The supernova had then a magnitude of 16.3. The spectrum of the supernova obtained on November 5 indicated it was a type Ia supernova about one or two months after maximum light.
Nearby galaxies.
NGC 3665 is the brightest member of a galaxy group known as the NGC 3665 group. Other members of the group include NGC 3648, NGC 3652, NGC 3658, and UGC 6433. NGC 3658 lies 15 arcminutes from NGC 3665.


Gamma Trianguli

Gamma Trianguli (Gamma Tri, γ Trianguli, γ Tri) is a star in the constellation Triangulum located approximately 112 light years from Earth. It has an apparent magnitude of +4.01 and forms an optical (line-of-sight) triple with Delta Trianguli and 7 Trianguli.
Properties.
This star has a stellar classification of A1Vnn, which indicates it is an A-type main sequence star. It has 2.7 times the mass of the Sun and nearly double the Sun's radius. Gamma Trianguli is radiating about 33 times the luminosity of the Sun from its outer envelope at an effective temperature of 9,440 K, giving the star a white hue. The star is roughly 300 million years old.
Rotation.
It is rotating rapidly, with a projected rotational velocity of 254 km/s along the equator, which causes the star to take the pronounced shape of an oblate spheroid like Altair. Because the inclination of the star's axial tilt is unknown, this means that the azimuthal equatorial velocity is at least this amount and possibly higher. By comparison, the Sun is a slow rotator with an equatorial azimuthal velocity of 2 km/s. The doppler shift from the rapid rotation results in very diffuse absorption lines in the star's spectrum, as indicated by the 'nn' in the classification.
Debris disk.
Orbiting the star is a dusty debris disk with a combined mass of about times the mass of the Earth. This disk can be detected because it is being heated to a temperature of about 75 K by Gamma Trianguli and is radiating this as infrared energy. The disk is separated from the host star by an angle of 2.24 arcseconds, corresponding to a physical radius of 80 AU, or 80 times the separation of the Earth from the Sun.
Naming.
In Chinese, (), meaning "Heaven's Great General", refers to an asterism consisting of γ Trianguli, γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli, and δ Trianguli. Consequently, the Chinese name for γ Trianguli itself is (, .).


HD 64740

HD 64740 is a class B1.5V (blue main-sequence) star in the constellation Puppis. Its apparent magnitude is 4.63 and it is approximately 760 light years away based on parallax.


Tau Geminorum

Tau Geminorum, Latinized from τ Geminorum, is a star in the northern zodiac constellation of Gemini. It has the apparent visual magnitude of +4.42, making it visible to the naked eye under suitably good seeing conditions. This star is close enough to the Earth that its distance can be measured using the parallax technique, which yields a value of roughly .
It is an evolved giant star of the spectral type K2 III. It has double the mass of the Sun and has expanded to 27 times the Sun's radius. Tau Geminorum is radiating 224 as much radiation as the Sun from its expanded outer atmosphere at an effective temperature of 4,528 K, giving it the characteristic orange-hued glow of a K-type star. It appears to be rotating slowly with a projected rotational velocity of .
This star has a brown dwarf or Super-Jupiter companion called Tau Geminorum b, whose mass is 18.1 Jupiter masses, and which was discovered in 2004 by Mitchell et al., who also discovered Nu Ophiuchi b at the same time. This brown dwarf takes 305 days or 0.84 years or 26.4 megaseconds to revolve around Tau Gem.


49 Cassiopeiae

49 Cassiopeiae is a binary star system in the northern circumpolar constellation of Cassiopeia. It is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 5.22. The system is located about 412 light years away from the Sun, based on parallax. The pair had an angular separation of along a position angle of 244°, as of 2008, with the brighter component being of magnitude 5.32 and its faint companion having magnitude 12.30.
The primary, designated component A, is an aging giant star with a stellar classification of G8III. It is 302 million years old with 3.3 times the mass of the Sun. With the supply of hydrogen at its core exhausted, the star has now expanded to 16 times the Sun's radius. It is a red clump giant on the horizontal branch, which indicates it is generating energy through the fusion of helium at its core. The star is radiating 142 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,957 K. Its faint secondary companion, component B, is of an unknown spectral type.


Sigma Pegasi

σ Pegasi, Latinised as Sigma Pegasi, is a binary star system in the northern constellation of Pegasus. With a combined apparent visual magnitude of 5.16, it is faintly visible to the naked eye. Based upon an annual parallax shift of 36.66 mas as seen from Earth, the system is located 89 light years distant from the Sun. It has a relatively high proper motion, advancing across the celestial sphere at the rate of 0.524 arcseconds per year.
The primary, component A, is a yellow-white hued F-type main-sequence star with a stellar classification of F6 V. However, Frasca et al. (2009) lists it as a somewhat more evolved F-type subgiant star with a class of F7 IV. At the age of 2.7 billion years, it has an inactive chromosphere and is spinning with a leisurely projected rotational velocity of 3 km/s. It has a faint, magnitude 13.23 red dwarf companion, designated component B, at an angular separation of 248 arc seconds. The system is most likely (96% chance) a member of the thin disk population of the Milky Way.


NGC 2500

NGC 2500 is a barred spiral galaxy in the constellation Lynx which was discovered by William Herschel in 1788. Much like the local group in which our own Milky Way galaxy is situated, NGC 2500 is part of NGC 2841 group of galaxies which also includes NGC 2541, NGC 2537 and NGC 2552. It has a H II nucleus and exhibits a weak inner ring structure.


Kappa Crateris

Kappa Crateris (κ Crateris) is the Bayer designation for a star in the southern constellation of Crater. It has an apparent visual magnitude of 5.94, which, according to the Bortle scale, can be seen with the naked eye under dark suburban skies. The distance to this star, as determined from an annual parallax shift of 14.27 mas, is around 229 light years.
This is an evolved F-type giant star with a stellar classification of F5/6 III, where the F5/6 indicates the spectrum lies intermediate between types F5 and F6. It is an estimated 1.74 billion years old and is spinning with a projected rotational velocity of 39 km/s. Kappa Crateris has 1.74 times the mass of the Sun, and radiates 17 times the solar luminosity from its outer atmosphere at an effective temperature of 6,545 K.
Kappa Crateris has a visual companion: a magnitude 13.0 star located at an angular separation of 24.6 arc seconds along a position angle of 343°, as of 2000.


Zeta Tauri

Zeta Tauri (ζ Tauri, abbreviated Zeta Tau, ζ Tau) is a binary star in the zodiac constellation of Taurus, the Bull. It has an apparent visual magnitude of 3.0, which is bright enough to be seen with the naked eye. Parallax measurements place it at a distance of roughly 440 light-years from the Sun.
The two components are designated Zeta Tauri A (officially named Tianguan ) and B.
Nomenclature.
"ζ Tauri" (Latinised to "Zeta Tauri") is the star's Bayer designation; it also bears the Flamsteed designation of 123 Tauri. The designations of the two components as "Zeta Tauri A" and "B" derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
In Chinese astronomy, Zeta Tauri is called 天關, Pinyin: Tiānguān, formerly transliterated "Tien Kwan", meaning "Celestial [Frontier] Gate", an asterism within the Net (畢宿 "Bì Xiù") mansion (see also: Chinese constellation). 天關 (Tiānguān) has also been transliterated as "Tien Kwan". (Technically, Tiānguān refers not just to Zeta Tauri but to an asterism of which Zeta Tauri is the main star, alongside 113, 126, 128, 129, 130 and 127 Tauri - see Taurus (Chinese astronomy).) In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name "Tianguan" for the component Zeta Tauri A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
Properties.
Zeta Tauri is a single-lined spectroscopic binary system, which means the two components are orbiting so close to each other that they can not be resolved with a telescope. Instead, the orbital motion of the primary component is indicated by Doppler effect shifts in the absorption lines in its spectrum. The two components are separated by an estimated distance of about 1.17 astronomical units, or 117% of the distance from the Earth to the Sun. They are following circular orbits with a period of nearly 133 days.
Compared to the Sun, the primary, Zeta Tauri A, is an enormous star with more than 11 times the mass and 5–6 times the radius. It is rotating rapidly with a projected rotational velocity of . The companion, Zeta Tauri B, has about 94% the mass of the Sun, although it is unknown whether this is a main sequence star, a neutron star, or a white dwarf. If it is a main sequence star, then the mass indicates it may have a stellar classification of G4.
The spectrum of the primary component has a stellar classification of B2 IIIpe. A luminosity class of 'III' indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. The 'p' suffix indicates an unspecified chemical peculiarity in the spectrum, while 'e' is used for stars that display emission lines. For Be stars such as this, the emission lines are produced by a rotating circumstellar disk of gas, made of material that has been ejected from the star's outer envelope. An oscillatory pattern in this spectrum is being caused by a single-armed spiral density wave in the disk. The disk may be precessing from the gravitational influence of the secondary component.
Zeta Tauri shows variation in its spectrum and brightness. The General Catalogue of Variable Stars lists it as an eclipsing variable and a Gamma Cassiopeiae variable, but it may not be either. Hrvoje Božić and Krešimer Pavlovski, of Hvar Observatory in Croatia, monitored the brightness of Zeta Tauri from 1981 to 1986 and noticed an eclipse like effect in the light curve. A latter study of all the available photometric data, including from the Hipparcos spacecraft, failed to confirm the presence of eclipses.
See also.
White Tiger of The West


NGC 6067

NGC 6067 is an open cluster in the constellation Norma. It is located to the north of Kappa Normae, with an angular diameter of 12′. Visible to the naked eye in dark skies, it is best observed with binoculars or a small telescope, and a 12-inch aperture telescope will reveal about 250 stars. Discovered by James Dunlop in 1826, it has been described by John Herschel as "a most superbly rich and large cluster" and by Stephen James O'Meara as "one of the sky’s most stunning open star clusters". Its brightest stars have an apparent magnitude of around 8. There are 84 member stars with an apparent magnitude brighter than 12.
NGC 6067 is located in the Norma Star Cloud in the Norma Arm of the Milky Way and is 15 to 20 times as rich as the Pleiades and about the same age. It is thought to be around 102 million years old, and contain 893 solar masses. Two Cepheid variables, QZ Normae and V340 Normae, have been identified as members of the cluster, while a third nearby Cepheid—GU Normae—is considerably closer. Its period is only 3.5 days compared with the longer period of V340 Normae, indicating it is intrinsically less luminous (and hence closer), and its age has been estimated at 134 million years and hence too old to belong to the cluster. V340 Normae is a yellow supergiant of spectral type G0Ib that varies between magnitudes 8.26 and 8.60 over 11.28 days, while the fainter QZ Normae varies between magnitudes 8.71 and 9.03 over 3.79 days.


Palomar 2

Palomar 2 is a globular cluster located in the constellation of Auriga. Palomar 2 is part of a group of 15 globulars known as the Palomar clusters, discovered in survey plates from the first National Geographic Society – Palomar Observatory Sky Survey in the 1950s.


EU Andromedae

EU Andromedae (often abbreviated to EU And) is a carbon star in the constellation Andromeda. Its apparent visual magnitude varies in an irregular manner between 10.7 and 11.8.
Infrared observations of EU Andromedae show the presence of silicate grains, indicating the presence of an oxygen-rich circumstellar shell around the star, a combination known as a silicate star. Subsequently, a water maser was detected around this star (and for the first time around a carbon star), confirming the existence of the shell. The most recent observations suggest that the maser originated in a circumstellar disc, seen nearly edge-on, around an unseen companion with a minimum mass of 0.5 . Carbon dioxide has been detected for the first time in a silicate carbon star around EU Andromedae.
EU Andromedae is given as the standard star for the C-J5− spectral class. C-J spectral types are assigned to stars with strong isotopic bands of carbon molecules, defined as the ratio of to being less than four. A more complete spectral type includes the abundance indices C25 j3.5, which indicate the Swan band strength and the isotopic band ratio.


Nu Cephei

Nu Cephei (ν Cephei) is a class A2, fourth-magnitude supergiant star in the constellation Cepheus. It is a white pulsating α Cygni variable star located about 4,700 light-years from Earth.
ν Cephei is a member of the Cepheus OB2 stellar association, which includes stars such as μ Cephei and VV Cephei. It began life as an approximately star around eight million years ago. It has now exhausted its core hydrogen and expanded and cooled into a supergiant. Elemental abundance analyses indicate that it has not yet spent time as a red supergiant, which would have brought about convection of fusion products to the surface in a Dredge-up.
ν Cephei is currently about 15 times as massive as the sun, 190 times as large, and 100,000 times as luminous. Its large size and luminosity cause it to be somewhat unstable and produce irregular pulsations. This is a common feature of class A and B supergiants, which are grouped as α Cygni variable stars. The brightness changes by at most a tenth of a magnitude.


Beta Microscopii

β Microscopii, Latinised as Beta Microscopii, is a faint, white-hued star in the constellation Microscopium. It is close to the lower limit of stars that are visible to the naked eye having an apparent visual magnitude of +6.04. Based upon an annual parallax shift of 6.76 mas as seen from Earth, this star is located roughly 480 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust.
This is an A-type main-sequence star with a stellar classification of A2 Vn, where 'n' indicates nebulous absorption lines caused by fast rotation. It is spinning rapidly with a projected rotational velocity of 275 km/s. The star has about 2.2 times the radius of the Sun and it is radiating 66 times the Sun's luminosity from its photosphere at an effective temperature of 8,586 K.


Tau9 Eridani

Tau9 Eridani (τ9 Eri) is a binary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.63. The distance to this system can be estimated using the parallax method, which yields a value of roughly 327 light years.
This is a single-lined spectroscopic binary system with an orbital period of 5.95382 days and an eccentricity of 0.12. The primary component, τ9 Eri A, is a magnetic chemically peculiar star with a stellar classification of , indicating that it is a B-type main sequence star that shows abundance anomalies in its silicon absorption lines. It is an Alpha² Canum Venaticorum variable with a rotational periodicity of 5.954 days. The averaged strength of the stellar effective magnetic field is .
The primary component Tau9 Eridani A has an estimated 326% the mass of the Sun and 3.1 times the Sun's radius. It shines with 166 times the solar luminosity from an outer atmosphere at an effective temperature of 10,866 K. The star is spinning with a projected rotational velocity of 30 km/s. The secondary star, designated Tau9 Eridani B, is a late A-type or early F-type star with a mass of 1.6 solar masses and an effective temperature of 7530 K.


Psi Draconis

The Bayer designation Psi Draconis (ψ Dra / ψ Draconis) is shared by two star systems, in the constellation Draco:


NGC 2936

NGC 2936 is an interacting spiral galaxy located at a distance of 326 million light years, in the constellation Hydra. NGC 2936 is interacting with elliptical galaxy NGC 2937, located just beneath it. They were both discovered by Albert Marth on Mar 3, 1864. To some astronomers, the galaxy looks like a penguin or a porpoise. NGC 2936, NGC 2937, and PGC 1237172 are included in the Atlas of Peculiar Galaxies as Arp 142 in the category "Galaxy triplet".
On 20 June 2013, the Hubble Space Telescope examined and photographed NGC 2936.
NGC 2936 was once part of a flat, spiral disk. The orbits of the galaxies stars have been mixed due to gravitational tidal interactions with NGC 2937. Gas from the center of NGC 2936 became compressed out during the encounter with NGC 2937, which is shown as blue knots closest to NGC 2937. The red dust that has been inside the center of the galaxy has been mostly thrown out due to the collision. During the collision, gas coming from NGC 2936 triggered star formation.
PGC 1237172, an unrelated bluish irregular galaxy or edge-on spiral galaxy, is located just off to the side of NGC 2936. It is located 230 million light years away, making it closer to the Earth than the NGC 2936 collision, and it happens to be located next to two unrelated stars from the Milky Way.


WR 20a

WR 20a is an eclipsing binary star belonging to or recently (0.5 millions years before present) ejected from the young, massive cluster Westerlund 2. It was discovered in 2004 to be one of the most massive binary systems known, for which the masses of the components have been accurately measured.
Each star in the system has about eighty times the mass of the Sun. It is not clear why this system is located away from the center of the cluster. It is possible that the system was formed in the core, but that it was ejected by dynamical interactions.
Every 3.6 days the two stars in this system revolve around each other. Although the stars are in a very tight orbit, both stars in the system are detached. The two stars eclipse each other on each orbit, producing a drop in brightness of about 0.4 magnitudes. The brightness is also continuously variable outside the eclipses due to the distorted shapes of the two stars. The primary and secondary minima are almost the same depth since the size and temperature of each star is almost identical.
It is expected that within a million years the two will expand and come into contact. A large nitrogen abundance has been measured on the surface of the stars, about six times the abundance of nitrogen measured in the sun. This nitrogen is probably produced in deeper layers of the star and pushed towards the surface by rotational mixing.
A collision between the two winds of the systems has been detected in the visible as well as in X-rays. The X-ray emitting region is quite extended since it does not suffer from any eclipse.


Lambda Coronae Borealis

Lambda Coronae Borealis, its name Latinised from λ Coronae Borealis, is a single star in the northern constellation of Corona Borealis. In publications it is also identified as HR 5936 and HD 142908. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.43. The star is located at a distance of 136 light years based on parallax, but is drifting closer with a radial velocity of −12 km/s.
The stellar classification of Lambda Coronae Borealis is F2 IV-V, which means it is somewhat hotter than the sun and shows spectral features intermediate between a main sequence and subgiant star. It has an estimated age of 1.4 billion years with a relatively high projected rotational velocity of 76 km/s. The star has 1.6 times the mass of the Sun and 2.1 times the Sun's radius. Based on the amount of iron in the atmosphere, the elemental abundances are similar to those in the Sun. It is radiating 9.4 times the luminosity of the Sun from its photosphere at an effective temperature of 6,991 K.
The star displays an infrared excess with a signature that indicates a pair of circumstellar disks of dusty debris are orbiting the star. A blackbody fit to the higher temperature signal gives a temperature of 320 K with an orbital distance of . The cooler outer disk is orbiting from the star with a temperature of .
A magnitude 11.44 visual companion was discovered by W. Herschel in 1782. As of 2015, it was located at an angular separation of from the brighter component, along a position angle of 68°.


Eta Circini

Eta Circini, Latinized from η Circini, is the Bayer designation for a solitary star located in the southern constellation of Circinus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.17. The distance to this star, as determined from an annual parallax shift of 11.82 mas, is around 276 light years.
This is an evolved G-type giant star with a stellar classification of G8 III. It is radiating an estimated 64 times the solar luminosity from its outer atmosphere at an effective temperature of 4,954 K.


35 Arietis

35 Arietis (abbreviated 35 Ari) is a binary star in the northern constellation of Aries. "35 Arietis" is the Flamsteed designation. It is approximately distant from the Earth, based upon an annual parallax shift of 9.51 mas. This star is visible to the naked eye with an apparent visual magnitude of 4.64.
This is a single-lined spectroscopic binary system, with the presence of a companion being demonstrated by shifts in the spectrum of the primary component. The pair orbit each other with a period of 490.0 days and an eccentricity of 0.14. The primary is a B-type main-sequence star with a stellar classification of B3 V. With a mass around 5.7 times that of the Sun, it is radiating 870 times the Sun's luminosity. This energy is being emitted from the outer atmosphere at an effective temperature of 17,520 K, causing it to shine with the blue-white hue of a B-type star.