4 Ursae Majoris

4 Ursae Majoris (sometimes abbreviated 4 Uma) is the Flamsteed designation of a star in the northern circumpolar constellation of Ursa Major. It also bears the Bayer designation of Pi² Ursae Majoris (Pi² UMa, π² Ursae Majoris, π² UMa) and is traditionally named Muscida. With an apparent visual magnitude of +4.6, this star is visible from suburban or darker skies based upon the Bortle Dark-Sky Scale. From parallax measurements made during the Hipparcos mission, this star is at a distance of from Earth. , one extrasolar planet has been confirmed to be orbiting the star.
Properties.
This star has a stellar classification of K2 III, indicating that, at an estimated age of around four billion years, it is an evolved star that has reached the giant stage. It has a mass about 1.2 times larger than the Sun, but has expanded to 18 times the Sun's girth. The effective temperature of the star's outer atmosphere is 4,415 K. This heat gives it the cool, orange-hued glow of a K-type star.
Pi² Ursae Majoris is a member of the Milky Way galaxy's thin disk population. It is following an orbit through the galaxy with an eccentricity of 0.10, which carries it as close to the Galactic Center as and as far as . The inclination of this orbit lies close to the galactic plane, so it departs this plane by no more than
Planetary system.
Based upon observed radial velocity changes in the star, in 2007 the presence of a planetary companion was announced. The planet, designated 4 Ursae Majoris b, is at least seven times more massive than Jupiter. Its orbit is eccentric, orbiting 4 Ursae Majoris at 87% the distance from Sun to Earth. Compared to the Sun, this star has a lower abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity. This is curious, because most main sequence stars with planets tend to have a higher abundance of metals.
Naming and etymology.
With π1, σ1, σ2, ρ, A and d, it composed the Arabic asterism Al Ṭhibā᾽, the Gazelle. According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Ṭhibā" were the title for seven stars : A as "Althiba I", π1 as "Althiba II", this star (π2) as "Althiba III", ρ as "Althiba IV", σ1 as "Althiba V", σ2 as "Althiba VI", and d as "Althiba VII".


Nu Horologii

Nu Horologii, Latinized from ν Horologii, is the Bayer designation for a single star in the southern constellation of Horologium. It was catalogued by the Dutch explorer Frederick de Houtman in 1603. With an apparent visual magnitude of 5.3, this star can be seen with the naked eye from the southern hemisphere. (According to the Bortle scale, it can be seen at night from bright suburban skies.) Based upon parallax measurements made by the "Gaia" space observatory, Nu Horologii lies at a distance of 169 ± 1 light-years from Earth.
The stellar classification of A2 V indicates that it is an A-type main sequence star that is generating energy through thermonuclear fusion of hydrogen into helium at its core. Nu Horologii is larger and hotter than the Sun, with 190% of the Sun's mass, 188% of the radius of the Sun, and it shines with 16.7 times the solar luminosity. This is a young star with an estimated age of 540 million years, and it is spinning rapidly with a projected rotational velocity of 144 km/s along the equator. The effective temperature of the photosphere is 8,308 K, giving it the white-hued glow of an A-type star.
No orbiting companions down to the mass of a brown dwarf have been discovered within a radius of 150 AU of Nu Horologii. However, it is emitting an infrared excess that suggests it is being orbited by a debris disk of dust particles. The mean temperature of this disk is 56 K and it appears to have two components: an inner disk is orbiting at a distance of , while an outer disk lies from the star. The estimated mass of the disks is times the mass of the Earth. The disks may be viewed edge on, which limits the amount of detail that can be discerned.
Based upon their respective motions through space, ν Horologii had a close encounter with the star Alpha Fornacis some 351,200 years ago. The two stars came within of each other; close enough to disrupt their respective (hypothetical) Oort clouds. Potentially, the interaction may have produced asymmetries in the Nu Horologii debris disk, and could cause comet showers that increase the dust content. However, it is unlikely that the encounter was the cause of the disk itself.


HD 9446

HD 9446 is a star located about 164 light-years away in the constellation of Triangulum, near the southwestern constellation border with Pisces. This object can be viewed with binoculars or a telescope, but it is too faint to be seen with the naked eye at its apparent visual magnitude of 8.35. It is drifting further away from the Sun with a radial velocity of +21 km/s.
This object is a G-type main sequence star with a stellar classification of G5V. The physical properties this star appear similar to the Sun, making it a candidate solar analog. However, the measured abundance of elements with more mass than helium is outside the accepted range. It is roughly two billion years in age and has an active chromosphere. The amount of activity measured in the chromosphere corresponds to a star with a rotation period of about 10 days.
On 5 January 2010, scientists announced the discovery of two planets orbiting around HD 9446.


UGC 9425


Tau Eridani

Tau Eridani (τ Eridani, τ Eri) is a group of fairly widely scattered stars in the constellation Eridanus.
They form an exception to the general rule that stars that share the same Bayer designation are close together: τ1 is nearly 20° away from τ9 (Pi Orionis is another example of this).
All of them were member of asterism 天苑 (Tiān Yuàn), "Celestial Meadows", "Hairy Head" mansion.


Delta3 Canis Minoris

Delta3 Canis Minoris, Latinized from δ3 Canis Minoris, is a solitary, white-hued star in the equatorial constellation of Canis Minor. Based upon a parallax of as seen from Gaia spacecraft in its repeated orbits around the sun, just beyond the earth this star is about 730 light years from the solar system. At that distance, the visual magnitude of these stars is diminished by an extinction of more than 0.15 due to interstellar dust. With an apparent visual magnitude of +5.81, it is just bright enough to be faintly visible to the naked eye.
This is a B-type main-sequence star with a stellar classification of B9 V. It is about of the way through its main sequence lifetime and is spinning rapidly with a projected rotational velocity of 259 km/s. The star has an estimated 3.16 times the mass of the Sun and about 2.1 times the Sun's radius. It is radiating 175 times the Sun's luminosity from its photosphere at an effective temperature of 9,908 K.


Delta Scorpii

Delta Scorpii (Latinised from δ Scorpii, abbreviated Delta Sco, δ Sco) is a binary star (the presence of a third star in the system is being debated) in the constellation of Scorpius. The primary star is named Dschubba .
Observation.
Delta Scorpii is 2.0 degrees south of the ecliptic. In 1981 it was occulted by Saturn's rings as seen by Voyager 2, with starlight unexpectedly blocked even by the apparently empty gaps, indicating that "there is very little empty space anywhere in the main ring system."
Variability.
Delta Scorpii A is a Gamma Cassiopeiae variable star. This type of star shows irregular slow brightness variations of a few hundredths of a magnitude due to material surrounding the star.
In June 2000 Delta Scorpii was observed by Sebastian Otero to be 0.1 magnitudes brighter than normal; its brightness has varied since then and has reached at least as high as magnitude 1.6, altering the familiar appearance of Scorpius. Spectra taken after the outburst began have shown that the star is throwing off luminous gases from its equatorial region. The companion passed close by in 2011, again resulting in the star peaking at 1.65 between 5 and 15 July 2011.
Nomenclature.
"δ Scorpii" (Latinised to "Delta Scorpii") is the system's Bayer designation. The two components are designated "Delta Scorpii A" and "B".
Delta Scorpii bore the traditional name "Dschubba". 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 "Dschubba" for "δ" "Scorpii A" on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese, (), meaning "Room", refers to an asterism consisting of δ Scorpii, β1 Scorpii, β2 Scorpii, π Scorpii, and ρ Scorpii. Consequently, the Chinese name for δ Scorpii itself is (), "the Third Star of Room".
Properties.
δ Scorpii was once used as a spectroscopic standard for the B0 IV classification, but is now considered too unusual and variable.
The primary, δ Scorpii A, is a B class subgiant surrounded by a disc of material spun off by the rapidly rotating star. The secondary, δ Scorpii B, orbits every 10.5 years in a highly elongated elliptical orbit; it appears to be normal B class main sequence star. There have been reports that Delta Scorpii A is itself a very close spectroscopic binary, but this does not appear to be the case.
δ Scorpii is a proper motion member of the Upper Scorpius subgroup of the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.
The Upper Scorpius subgroup contains thousands of young stars with mean age 11 million years at average distance of 470 light years (145 parsecs).


Stingray Nebula

The Stingray Nebula (Hen 3-1357) is the youngest known planetary nebula. The Stingray is located in the direction of the southern constellation Ara (the Altar), and is located 18,000light-years away. Although it is some 130 times the size of the Solar System, the Stingray Nebula is only about 1/10 the size of most other known planetary nebulae. The central star of the nebula is the fast-evolving star SAO 244567. Until approximately forty years ago, it was observed on Earth as a preplanetary nebula in which the gas had not yet become hot and ionized.
The image of the nebula shows how the outer shells of gas are collimating the continuing outflow of gas from the central star—an important observation, as the process of how these outflows become collimated has not been well understood.
History.
Prior to the discovery of the nebula, its central star was known as He 3-1357, which Karl Gordon Henize classified as an A or B type Hα emission line star in 1967. It was observed in 1971 to be a preplanetary nebula when it seemed to be an asymptotic giant branch B1 supergiant. Planetary nebula emission lines were identified in this star in 1989 by the International Ultraviolet Explorer. As the nebula would be newly formed and very small, ground-based observations were not able to resolve it; so Bobrowsky observed it with the Hubble Space Telescope, discovering the nebula, which he named the "Stingray Nebula".
In 1995 the central planetary nebula nucleus was observed as a DA white dwarf, having seemingly faded by a factor of three between 1987 and 1995. The white dwarf has an estimated mass of and luminosity of and has an observed companion star separated by 0.3arcsec. Nebula mass is estimated as .
In 1998 Bobrowsky et al. described how the Hubble Space Telescope observations revealed a 17th-magnitude companion to the Stingray's 15th-magnitude central star.
The central star is unusual in that it has brightened and faded over a period of 20years. Its temperature went up by 40,000°C. An explanation for this is that it has undergone a helium flash.
In January 2021 NASA discovered that the nebula is fading. In a NASA statement a team member, Martín A. Guerrero of the Instituto de Astrofísica de Andalucía in Granada, Spain, said: "This is very, very dramatic, and very weird. What we're witnessing is a nebula's evolution in real time. In a span of years, we see variations in the nebula. We have not seen that before with the clarity we get with this view."


75 Cygni

75 Cygni is a binary star system in the northern constellation of Cygnus. It is visible to the naked eye as a dim, reddish-hued point of light with an apparent visual magnitude of 5.09. The system is located at a distance of about 434 light years from the Sun, based on parallax, and is drifting closer with a radial velocity of −29 km/s.
The pair had an angular separation of as of 2008, with the companion having a visual magnitude of 10.7. The brighter magnitude 5.18 primary is an aging red giant star with a stellar classification of M1IIIab. Having exhausted the supply of hydrogen at its core, it has expanded to around 45 times the radius of the Sun. It is a suspected variable star of unknown type and amplitude. The star is radiating 439 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,954 K.
An optical companion, with a spectral type of K, is about an arcminute away and has an apparent magnitude of 10.14.


Psi Tauri

Psi Tauri, which is Latinized from ψ Tauri, is a solitary star in the zodiac constellation of Taurus. It has a yellow-white hue and is visible to the naked eye with an apparent visual magnitude of +5.22. The distance to this system, as determined using an annual parallax shift of as seen from the Earth, is 90 light years. It is drifting further away with a radial velocity of +9 km/s.
This object is an F-type main sequence star with a stellar classification of F1 V, which indicates it is undergoing core hydrogen fusion. It is about 1.4 billion years old and is spinning with a projected rotational velocity of 45 km/s. The star has 1.6 times the mass and radius of the Sun. It is radiating 4.8 times the Sun's luminosity from its photosphere at an effective temperature of 7,088 K.


Albireo

The Albireo is a double star designated Beta Cygni (β Cygni, abbreviated Beta Cyg, β Cyg). The International Astronomical Union uses the name "Albireo" specifically for the brightest star in the system. Although designated 'beta', it is fainter than Gamma Cygni, Delta Cygni, and Epsilon Cygni and is the fifth-brightest point of light in the constellation of Cygnus. Appearing to the naked eye to be a single star of magnitude 3, viewing through even a low-magnification telescope resolves it into its two components. The brighter yellow star, itself a very close binary system, makes a striking colour contrast with its fainter blue companion.
Nomenclature.
"β Cygni" (Latinised to "Beta Cygni") is the system's Bayer designation. The brighter of the two components is designated "β¹ Cygni" or "Beta Cygni A" and the fainter "β² Cygni" or "Beta Cygni B".
The system's traditional name "Albireo" is a result of misunderstanding and mistranslation. It is thought that it originated in the Greek name ' for the constellation of Cygnus, which became ' in Arabic. When translated into Latin, this name was thought to refer to the Greek name "Erysimon" for the plant called Hedge Mustard ("Sisymbrium officinale", which in Latin is "ireo"), and so was described in Latin in the Arabo-Latin Almagest of 1515 as "Eurisim: et est volans; et jam vocatur gallina. et dicitur eurisim quasi redolens ut lilium ab ireo" ("Eurisim: and it is the flyer, and now it is called the hen, and it is called Eurisim, as if redolent like the lily from the 'ireo'"), via a confusion between "ireo" and the scented flower "Iris florentina". This was variously miscopied, until "ab ireo" was treated as a miscopy of an Arabic term and changed into "".
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 "Albireo " for β¹ Cygni. It is now so entered in the IAU Catalog of Star Names.
Medieval Arabic-speaking astronomers called Beta Cygni ' (English: "the hen's beak"). The term ' (منقار الدجاجة) or "Menchir al Dedjadjet" appeared in the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", which was translated into Latin as "Rostrum Gallinae", meaning "the hen's beak".
Since Cygnus is the swan, and Beta Cygni is located at the head of the swan, it is sometimes called the "beak star". With Deneb, Gamma Cygni (Sadr), Delta Cygni, and Epsilon Cygni (Gienah), it forms the asterism called the Northern Cross.
Properties.
Beta Cygni is about away from the Sun. When viewed with the naked eye, Albireo appears to be a single star. However, in a telescope it resolves into a double star consisting of β Cygni A (amber, apparent magnitude 3.1), and β Cygni B (blue-green, apparent magnitude 5.1). Separated by 35 seconds of arc, the two components provide one of the best contrasting double stars in the sky due to their different colors.
It is not known whether the two components β Cygni A and B are orbiting around each other in a physical binary system, or if they are merely an optical double. If they are a physical binary, their orbital period is probably at least 100,000 years. Some experts, however, support the optical double argument, based on observations that suggest different proper motions for the components, which implies that they are unrelated. The primary and secondary also have different measured distances from the Hipparcos mission – for the primary and for the secondary. More recently the Gaia mission has measured distances of about 330–390 light years (100–120 parsecs) for both components, but noise in the astrometric measurements for the stars means that data from Gaia's second data release is not yet sufficient to determine whether the stars are physically associated.
There are a further 10 faint companions listed in the Washington Double Star catalogue, all fainter than magnitude 10. Only one is closer to the primary than Albireo B, with the others up to 142" away.
Albireo A.
The spectrum of Beta Cygni A was found to be composite when it was observed as part of the Henry Draper Memorial project in the late 19th century, leading to the supposition that it was itself double. This was supported by observations from 1898 to 1918 which showed that it had a varying radial velocity. In 1923, the two components were identified in the Henry Draper Catalogue as HD 183912 and HD 183913.
In 1978, speckle interferometry observations using the 1.93m telescope at the Haute-Provence Observatory resolved a companion at 0.125". This observation was published in 1980, and the companion is referred to as component Ab in the Washington Double Star Catalog.
In 1976 speckle interferometry was used to resolve a companion using the 2.1-meter telescope at the Kitt Peak National Observatory. It was measured at a separation of 0.44", and it is noted that the observation was inconsistent with the Haute-Provence observations and hence not of the same star. Although these observations pre-dated those at Haute-Provence, they were not published until 1982 and this component is designated Ac in the Washington Double Star Catalog. It is designated as component C in the Catalog of Components of Double and Multiple Stars, not to be confused with component C in the Washington Double Star Catalog which is a faint optical companion. An orbit for the pair has since been computed using interferometric measurements, but as only approximately a quarter of the orbit has been observed, the orbital parameters must be regarded as preliminary. The period of this orbit is 214 years. The confirmed close pair are referred to as Aa and Ac in modern papers, with Ab being the unconfirmed third component.
The diameter of the primary K-type giant star has been measured using interferometry. A uniform disk of approximately 4.5 mas was measured at optical and near-infrared wavelengths, and a limb-darkened diameter of 4.834 mas was calculated, equivalent to a radius of at a distance of 133 pc.
Albireo B.
β Cygni B is a fast-rotating Be star, with an equatorial rotational velocity of at least 250 kilometers per second. Its surface temperature has been spectroscopically estimated to be about 13,200 K.
β Cygni B has been reported to be a very close double, but the observations appear to have been incorrect.
Moving group.
Analysis of Gaia Data Release 2 astrometry suggests that four fainter stars may form a moving group along with the brighter visible components.
Namesakes.
"Albireo" (AK-90) was a United States Navy "Crater"-class cargo ship named after the star.


Arp 87

Arp 87 (also known as NGC 3808) is a pair of two interacting galaxies, NGC 3808A and NGC 3808B. They are situated in the Leo constellation. NGC 3808A, the brighter, is a peculiar spiral galaxy, while NGC 3808B is an irregular galaxy.
The two galaxies were discovered on 10 April 1785 by William Herschel. The two are located about 330 million light-years (100 megaparsecs) away from the Earth. Arp 87 was observed by the Hubble Telescope in 2007, which revealed massive clouds of gas and dust flowing from one galaxy to another. Additionally, both galaxies appear to have been distorted.


Kepler-36

Kepler-36 is a star in the constellation of Cygnus with two known planets. It has an anomalously large radius, meaning that it is a subgiant.
Planetary system.
On June 21, 2012, the discovery of two planets orbiting the star was announced. The planets, a super-Earth and a "mini-Neptune", are unusual in that they have very close orbits; their semi-major axes differ by only 0.013 AU. The outer planet orbits only 11% further than the inner one. Coupled with masses significantly higher than Earth, their gravitational influence to each other is significant, meaning that their interaction causes extreme transit timing variations for both. Kepler-36b and c have estimated densities of 6.8 and 0.86 g/cm3, respectively. The two planets are close to a 7:6 orbital resonance. The large difference in densities, despite the close proximity of the planets' orbits, is likely due to the large difference in mass. The innermost and less massive planet likely lost most, or all, of the hydrogen/helium envelope acquired during formation.


HD 209458

HD 209458 is an 8th-magnitude star in the constellation Pegasus. It is a G0V star, and is thus very similar to the Sun. Because it is located at a distance of about 159 light years, it is not visible to the unaided eye. With good binoculars or small telescope it should be easily detectable.
In 1999, two teams working independently (one team consisted of astronomers at the Geneva Observatory, the Harvard-Smithsonian Center for Astrophysics, and the Wise Observatory; the second group was the California and Carnegie Planet Search team) discovered an extrasolar planet orbiting the star by using the radial velocity planet search method. Soon after the discovery, separate teams led by David Charbonneau and Gregory W. Henry were able to detect a transit of the planet across the surface of the star making it the first known transiting extrasolar planet. The planet received the designation "HD 209458 b".
Because the planet transits the star, the star is dimmed by about 2% every 3.5 days making it an extrinsic variable. The variable star designation for HD 209458 is V376 Pegasi. It is the prototype of the variable class "EP" in the General Catalogue of Variable Stars, defined as stars showing eclipses by their planets.
Planetary system.
HD 209458 b is an extrasolar planet that orbits the Sun-like star HD 209458 in the constellation Pegasus. Spectroscopic studies first revealed the presence of a planet around HD 209458 on November 5, 1999. The planet is now under even more public scrutiny with the announcement that its atmosphere contains water vapor. Astronomers had made careful photometric measurements of several stars known to be orbited by planets, in the hope that they might observe a dip in brightness caused by the transit of the planet across the star's face. This would require the planet's orbit to be inclined such that it would pass between the Earth and the star, and previously no transits had been detected.
Travis Barman at Lowell Observatory in Flagstaff, Arizona analyzed the emission spectrum of this planet in 2009, and believes that its atmosphere contains water, although previous research in 2007 suggests that the atmosphere is composed mostly of silicate clouds. The spectrum taken in 2020 did indeed feature either sodium or vanadium oxide, but not the water. Later study in 2021 did not find any planetary atmosphere at all.


NGC 4658

NGC 4658 is a spiral galaxy located in the constellation of Virgo. It was discovered by William Herschel in 1786.


60 Herculis

60 Herculis is a single star located 134 light years away from the Sun in the northern constellation of Hercules, and is positioned just seven degrees away from Rasalgethi (Alpha Herculis). It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.871. This star is moving closer to the Earth with a heliocentric radial velocity of −4 km/s.
Abt and Morrell (1995) assigned this star a stellar classification of A3V, matching an ordinary A-type main-sequence star. However, earlier studies gave it a luminosity class of IV, which suggested it is a subdwarf star. It has a projected rotational velocity of 117 km/s, which is creating an equatorial bulge that is 5% larger than the star's polar radius. The star is 327 million years old with 1.9 times the Sun's mass. It is radiating 17 times the luminosity of the Sun from its photosphere at an effective temperature of 8,299 K.


NGC 476

NGC 476 is a lenticular galaxy in the constellation Pisces. It is located approximately 261 million light-years from Earth and was discovered on November 3, 1864 by German astronomer Albert Marth.


GD 66

GD 66 or V361 Aurigae is a 0.64 solar mass () pulsating white dwarf star located 170 light years from Earth in the Auriga constellation. The estimated cooling age of the white dwarf is 500 million years. Models of the relationship between the initial mass of a star and its final mass as a white dwarf star suggest that when the star was on the main sequence it had a mass of approximately 2.5 , which implies its lifetime was around 830 million years. The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.
The star is a pulsating white dwarf of type DAV, with an extremely stable period. Small variations in the phase of pulsation led to the suggestion that the star was being orbited by a giant planet which caused the pulsations to be delayed due to the varying distance to the star caused by the reflex motion about the system's centre-of-mass. Observations with the Spitzer Space Telescope failed to directly detect the planet, which put an upper limit on the mass of 5–6 Jupiter masses. Investigation of a separate pulsation mode revealed timing variations in antiphase with the variations in the originally-analysed pulsation mode. This would not be the case if the variations were caused by an orbiting planet, and thus the timing variations must have a different cause. This illustrates the potential dangers of attempting to detect planets by white dwarf pulsation timing.


NGC 770

NGC 770 is an elliptical galaxy in the constellation Aries. It is around 120 million light years from the Milky Way and has a diameter of around . NGC 770 is gravitationally linked to NGC 772. The galaxy was discovered on November 3, 1855 by RJ Mitchell.


Theta Herculis

Theta Herculis is a single, variable star in the northern constellation of Hercules. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 3.851. Based upon parallax measurements, it is located around 750 light years away from the Sun. The star is advancing toward the Earth with a heliocentric radial velocity of –28 km/s.
This is an aging K-type bright giant with a stellar classification of K1IIaCN2, where the suffix notation indicates a strong overabundance of CN in the spectrum. The brightness variations of this star was first noticed in 1935 by M. Fedtke and confirmed by Erich Przybyllok and Kurt Walter the same year. French astronomer Paul Muller then classified Theta Herculis as an irregular variable with a range of magnitudes between 3.7 and 4.1 and a periodicity of roughly 8–9 days.
The star is about 130 million years old with 4.94 times the mass of the Sun. With the hydrogen at its core exhausted, the star has expanded to 90 times the Sun's radius. It is radiating 2,406 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,266 K.
Nomenclature and etymology.
"θ Herculis" is the Bayer designation, Latinised to Theta Herculis, abbreviated to θ Her or Theta Her.
In the "Calendarium of Al Achsasi Al Mouakket", this star was designated "Rekbet al Jathih al Aisr", which was translated into Latin as "Genu Sinistrum Ingeniculi", meaning "the left knee of the kneeling man". The traditional name "Rukbalgethi Genubi" that is encountered in various texts is etymologically similar to the stars Ruchbah and Zubenelgenubi, the term "ruchbah" meaning "knee" while "genubi" signifies "southern"—hence the "southern knee", a meaning which can be gleaned more easily by looking at the accompanying constellation map.
In Chinese, (), meaning "Celestial Discipline", refers to an asterism consisting of θ Herculis, ξ Coronae Borealis, ζ Herculis, ε Herculis, 59 Herculis, 61 Herculis, 68 Herculis and HD 160054. Consequently, the Chinese name for θ Herculis itself is (, .) It was also "Tien Ke", Heaven's Record.


W Coronae Borealis

W Coronae Borealis (W CrB) is a Mira-type long period variable star in the constellation Corona Borealis. Its apparent magnitude varies between 7.8 and 14.3 over a period of 238 days.


HD 83944

HD 83944 is a star system in the constellation Carina. This has the Bayer designation "m Carinae", while "HD 83944" is the identifier from the "Henry Draper catalogue". It is a suspected variable with an apparent visual magnitude that fluctuates around 4.51 with an amplitude of 0.5. The system is located at a distance of approximately 226 light years from the Sun based on parallax, and it has an absolute magnitude of 0.31. It is a member of the Carina association of co-moving stars.
Although previously believed to be a single star, Chini et al. (2012) found this to be a double-lined spectroscopic binary. The stellar classification of B9IV/V matches a star that is entering the subgiant phase, although stellar models suggest it is still in the main sequence.


AK Scorpii

AK Scorpii is a Herbig Ae/Be star and spectroscopic binary star about 459 light-years distant in the constellation Scorpius. The star belongs to the nearby Upper Centaurus–Lupus star-forming region and the star is actively accreting material. The binary is surrounded by a circumbinary disk that was imaged with VLT/SPHERE in scattered light and with ALMA.
Characteristics.
AK Scorpii is about 18 million years old, which is young on astronomical timescales. The binary consists out of two stars with an equal mass of 1.25 respectively and the two stars orbit each other within 13.6 days. The binary is surrounded by a narrow ring of dust with a radius of about 30 astronomical units and the gap between the binary and the dust disk is filled by some gas.
The binary is in an eccentric orbit that causes variable accretion rates due to gravitational interactions with the disk. During the furthest point in the orbit of the binary (apastron), matter is dragged from the inner disk border into the gap. The material forms accretion streams that fill ring-like structures around each component of the binary. At the closest point in the orbit (periastron), the ring-like structures come into contact, leading to an angular momentum loss and thus producing an accretion outburst.
In August 2014 the system was observed with the Hubble Space Telescope during the periastron passage. The telescope observed a drop of the hydrogen flux, which is explained by the occultation of the star by a gas stream falling towards the star. The system also shows an enhanced X-ray and ultraviolet flux with XMM-Newton data during periastron, which is an additional sign of stronger accretion during periastron.
The orbital inclination of the binary and the inclination of the circumbinary disk is nearly the same. Any circumbinary planet that could form in this disk would orbit in the same plane as the binary.
The spectrum of the stars shows that their atmosphere is overabundant in the chemical elements yttrium, barium, and lanthanum. The primary additionally shows an overabundance of zirconium and the secondary is overabundant in sulphur.


RW Cephei

RW Cephei is a hypergiant variable star in the constellation Cepheus, at the edge of the Sharpless 132 HII region and close to the small open cluster Berkeley 94. One of the largest stars known, RW Cephei's radius is more than 1,000 times that of the Sun (), thus larger than the orbit of Jupiter.
RW Cephei is also a semi-regular variable star of type SRd, meaning that it is a slowly varying yellow giant or supergiant. The visual magnitude range is from 6.0 to 7.3, while the photographic range is from 8.6 - 10.7. The General Catalogue of Variable Stars gives a period of approximately 346 days, but other studies suggest different periods and certainly no strong periodicity.
The spectral has been classified as early as G8 and as late as M2, but it isn't clear that there has been actual variation. In the first MK spectral atlas, it was listed M0:Ia. RW Cep was later listed as the standard star for spectral type G8 Ia, then as the standard for K0 0-Ia. Based on the same spectra it was adjusted to the standard star for type K2 0-Ia. Molecular bands characteristic of M-class stars are seen in infrared spectra, but not always in optical spectra. The temperature is equally uncertain, with contradictory excitation strengths in the spectrum. A simple colour correlation temperature fit gives temperatures around 3,749 K, while a full spectrum fit gives a temperature of 5,018 K.
The distance to RW Cephei has been estimated on the basis of its spectroscopic luminosity and is assumed to be a member of the Cepheus OB1 association at 3,500 parsecs, consistent with the parallax from Gaia Data Release 2.
The temperature intermediate between the red supergiants and yellow hypergiants, and itself varying considerably, has led to it being variously considered as a red hypergiant or yellow hypergiant.


Iota Librae

The Bayer designation Iota Librae (ι Lib / ι Librae) is shared by two star systems, in the constellation Libra:


Xi Persei

Xi Persei (ξ Persei, abbreviated Xi Per, ξ Per), formally named Menkib , is a star in the constellation of Perseus. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 1,200 light-years from the Sun.
Nomenclature.
"ξ Persei" (Latinised to "Xi Persei") is the star's Bayer designation.
It bore the traditional name "Menkib", "Menchib", "Menkhib" or "Al Mankib", from "Mankib al Thurayya" (Arabic for "shoulder" [of the Pleiades]). 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 "Menkib" for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Rolled Tongue", refers to an asterism consisting of Xi Persei, Nu Persei, Epsilon Persei, Zeta Persei, Omicron Persei and 40 Persei. Consequently, the Chinese name for Xi Persei itself is (, "the Third Star of Rolled Tongue").
Properties.
Xi Persei has an apparent magnitude of +4.06 and is classified as a blue giant (spectral class O7.5III). It is intrinsically 12,700 times brighter than the Sun with absolute magnitude −5.5 in the V band. If the ultraviolet light and light from other wavelengths that emanates from Menkib is included, its total bolometric luminosity is 263,000 times that of the Sun.
The star has a mass of some 30 solar masses and a surface temperature of 35,000 kelvins, making it one of the hottest stars that can be seen with the naked eye. The fluorescence of the California Nebula (NGC 1499) is due to this star's prodigious radiation. It is a member of the Perseus OB2 association of co-moving stars, but may be a runaway star since it is now separated by 200 pc from the association's center and has an unusually high radial velocity.


Zeta Geminorum

Zeta Geminorum (ζ Geminorum, abbreviated Zeta Gem, ζ Gem) is a bright star with cluster components, distant optical components and a likely spectroscopic partner in the zodiac constellation of Gemini — in its south, on the left 'leg' of the twin Pollux. It is a classical Cepheid variable star, of which over 800 have been found in our galaxy. As such its regular pulsation and luminosity (proven in its class to correspond) and its relative proximity means the star is a useful calibrator in computing the cosmic distance ladder. Based on parallax measurements, it is approximately 1,200 light-years from the Sun.
Zeta Geminorum is the primary or 'A' component of a multiple star system designated WDS J07041+2034. It bears traditional name Mekbuda, usually anglicised to .
Nomenclature.
"ζ Geminorum" (Latinised to "Zeta Geminorum") is the star's Bayer designation. WDS J07041+2034 A is its designation in the Washington Double Star Catalog. The designations of the two components as WDS J03158-0849 Aa and Ab derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Zeta Geminorum bore the traditional name "Mekbuda", from an Arabic phrase meaning "the lion's folded paw" (Zeta and Epsilon Geminorum (Mebsuta) were the paws of a lion). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue 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 "Mekbuda" for the component WDS J07041+2034 Aa on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Well (asterism)" consists of eight stars in Gemini: Zeta, Mu, Gamma, Nu, Xi, Epsilon, 36 and Lambda. Zeta is (, ).
Observation history.
In 1844, German astronomer Julius Schmidt discovered that Zeta Geminorum varies in brightness with a period of about 10 days, although it had been suspected of variability as early as 1790. It was recognised as being related to the Cepheid class of variable stars, although was often treated as the prototype of its own class, the Geminids, because of its symmetrical light curve.
In 1899, American astronomer W. W. Campbell announced the star to have a variable radial velocity. (This variation was independently discovered by Russian astronomer Aristarkh Belopolsky, published in 1901.) Based on his observations, Campbell later published orbital elements for the binary. However, he found that the curve departed from a keplerian orbit and even suggested that it was a triple star system to explain the irregularities. The periodic variation in radial velocity of the Cepheid variables was later explained as being due to pulsations in the atmosphere of the star.
The periodicity of the star is itself variable, a trend first noted by German astronomer Paul Guthnick in 1920, who suspected that the period change was the result of an orbiting companion. In 1930, Danish astronomer Axel Nielsen suggested that the change was instead the result in a steady decrease of about 3.6 seconds per year in the period.
Companions.
Zeta Geminorum has three visible companions known since the 19th century and listed in the Washington Double Star Catalog as B, C, and D. More recently, a possible spectroscopic companion has been listed, further faint stars close by have been catalogued, and a diffuse cluster has been identified as including Zeta Geminorum.
The brightest nearby star, WDS J07041+2034 C, is the magnitude 7.6 HD 268518, 91.9" away when discovered in 1779 and 101.3" distant in 2008. It is a foreground object, only a tenth the distance of Zeta Geminorum and a high proper motion star moving rapidly compared to the more distant stars. It is a G1 main sequence star very similar to the sun.
The closest visible companion is WDS J07041+2034 D, a 12th magnitude star measured to be 67.8" away in 2008. It was 80" distant when first measured in 1905. It appears on the sky between Zeta Geminorum and component C, but is a more distant object than either.
WDS J07041+2034 B is an 11th magnitude star, 76.0" distant in 1831 and 87.4" in 2008. It is itself a spectroscopic binary, although little is known about the two components. The combined spectrum is of an F4 main sequence star. It is thought to be physically associated with the supergiant primary and a member of a loose cluster of stars around Zeta Geminorum.
A combination of photometry, spectroscopy, and astrometry has identified 26 stars approximately 355 parsecs away, which are likely to be members of the birth cluster of Zeta Geminorum. The brightest are late B and early A giant stars such as the 7th magnitude stars HD 49381 and HD 50634, while the faintest detected cluster members are 12th magnitude class F main sequence stars including WDS J07041+2034 B.
Properties.
Zeta Geminorum has been reported to be a spectroscopic binary on the basis of lunar occultation observations, but this has not been confirmed by other methods.
Zeta Geminorum's primary (WDS J07041+2034 Aa) is a Classical Cepheid variable that undergoes regular, periodic variation in brightness because of radial pulsations. In the V band, the apparent magnitude varies between a high of 3.68 and a low of 4.16 (with a mean of 3.93) over a period of 10.148 days. This period of variation is decreasing at the rate of 3.1 seconds per year, or 0.085 seconds per cycle. The spectral classification varies between F7Ib and G3Ib over the course of a pulsation cycle. Likewise the effective temperature of the outer envelope varies between 5,780 K and 5,260 K, while the radius varies from 61 to 69 times the Sun's radius. On average, it is radiating about 2,900 times the luminosity of the Sun.
Membership of a cluster provides independent validation of distances determined using recent Hubble Space Telescope and Hipparcos parallaxes. This strongly constrains the star's distance: parsecs. Zeta Geminorum is thus an important calibrator for the Cepheid period-luminosity relation used for establishing the cosmic distance ladder. The Gaia Data Release 2 parallax of suggests the distance is towards the top end of this range, and has a comparable margin of error.


Rangifer (constellation)

Rangifer was a small constellation between the constellations of Cassiopeia and Camelopardalis. It was also known as Tarandus. Both words mean "reindeer" in Latin. ""Rangifer" is the generic name of the reindeer, and "tarandus"" is the specific name.
History.
The constellation Rangifer was created by the French astronomer Pierre Charles Le Monnier in 1736 to commemorate the expedition of Maupertuis to Lapland. Geodetical observations from the expedition proved Earth's oblateness. The constellation is no longer in use.


Xi Canis Majoris

The Bayer designation Xi Canis Majoris (ξ CMa / ξ Canis Majoris) is shared by two star systems, in the constellation Canis Major:
They are separated by 0.86° on the sky.
ξ¹ Canis Majoris was member of asterism 軍市 (Jūn Shì), "Market for Soldiers", "Well" mansion. ξ² Canis Majoris was not any member of asterism.


Furuhjelm 46

Furuhjelm 46, also known as HD 155876 and Gliese 661, is a nearby binary star system, consisting of two very similar red dwarfs, located in the constellation Hercules.
Furuhjelm 46 is the nearest "true" (i. e. not brown dwarf) star system in Hercules, however, there is brown dwarf in this constellation, located closer: WISE 1741+2553.


Kappa Sculptoris

The Bayer designation Kappa Sculptoris (κ Scl, κ Sculptoris) is shared by two star systems, κ¹ Sculptoris and κ² Sculptoris, in the constellation Sculptor. They are separated by 0.53° in the sky.


HD 92589

HD 92589 is a double or multiple star in the constellation Antlia.


56 Ursae Majoris

56 Ursae Majoris (56 UMa) is a star in the constellation Ursa Major. Its apparent magnitude is 5.03. It is a single-lined spectroscopic binary with an orbital period of about 45 years.


64 Draconis

64 Draconis is a single star in the northern circumpolar constellation of Draco, located 452 light years away. It has the Bayer designation of e Draconis; "64 Draconis" is the Flamsteed designation. The object is visible to the naked eye as a dim, red-hued star with an apparent visual magnitude of 5.27. It is moving closer to the Earth with a heliocentric radial velocity of −36 km/s, and it is predicted to come as close as in around 4.3 million years.
This is an evolved red giant star with a stellar classification of M1 III, currently on the asymptotic giant branch. It has expanded to about 65 times the Sun's radius and is radiating 926 times the Sun's luminosity from its photosphere at an effective temperature of . 64 Draconis forms a faint naked-eye pair with 65 Draconis away. The latter is a suspected variable with a brightness range in the Hipparcos photometric filter of 5.29 to 5.33.
In Chinese astronomy, it belongs to the () ("Celestial Kitchen") asterism.


PZ Telescopii

PZ Telescopii, also known as HD 174429 or simply PZ Tel, is a young star in the constellation Telescopium. Based on parallax measurements, it is located at a distance of 154 light years from the Sun. The star is drifting closer with a radial velocity of −4 km/s. It is too faint to be visible to the naked eye and is classified as a BY Draconis variable that ranges in apparent visual magnitude from 8.33 down to 8.63 over a period of . It is one of the closest and hence brightest pre-main-sequence stars to Earth.
PZ Telescopii has an effective surface temperature of around 5,338 K (the Sun has an approximate surface temperature of 5,778 K), a mass around 1.13 times, and diameter 1.23 times that of the Sun. The star has a high rate of spin, showing a projected rotational velocity of 69 km/s and a rotation period of . It is radiating about the same luminosity as the Sun. PZ Telescopii was originally considered to be a member of the Beta Pictoris moving group; however in a 2012 paper, James Jenkins of Universidad de Chile and colleagues used three methods to calculate its age and came up with a figure of around 24 million years—significantly older than the 12 million years of the association.
This star has an orbiting debris disk calculated to span from a radius of 35 to 165 astronomical units (AU), as well as a substellar companion with 36 times the mass of Jupiter orbiting at a distance of 16 AU, discovered in 2008. The companion, currently known as PZ Tel B, is thought to be a brown dwarf; however it is possible (though very unlikely) that it is an extremely large Jupiter-like planet, in which case it would be PZ Tel b, and the first such planet to be directly imaged. Preliminary orbital elements give a best fit orbital period of 622.2 years with an eccentricity of 0.755.


Kappa Persei

Kappa Persei (κ Persei, abbreviated Kap Per, κ Per) is a triple star system in the northern constellation of Perseus. Based upon an annual parallax shift of 28.93 mas, it is located at a distance of 113 light-years from the Sun.
The system consists of a spectroscopic binary, designated Kappa Persei A, which can be seen with the naked eye, having an apparent visual magnitude of 3.80. The third star, designated Kappa Persei B, is of magnitude 13.50.
Kappa Persei A's two components are designated Kappa Persei Aa (officially named Misam , the traditional name of the entire system) and Ab.
Nomenclature.
"κ Persei" (Latinised to "Kappa Persei") is the system's Bayer designation. The designations of the two constituents as "Kappa Persei A" and "B", and those of "A's" components - "Kappa Persei Aa" and "Ab" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
The traditional name comes from the Arabic مِعْصَم "miʽṣam" 'wrist'.
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 "Misam" for the component Kappa Persei Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Mausoleum", refers to an asterism consisting of Kappa Persei, 9 Persei, Tau Persei, Iota Persei, Beta Persei (Algol), Rho Persei, 16 Persei and 12 Persei. Consequently, the Chinese name for Kappa Persei itself is (, .).
Properties.
At its distance, the visual magnitude of Kappa Perseii is diminished by an extinction factor of 0.06 due to interstellar dust. It has a relatively high proper motion totaling 0.230 arcseconds per year. There is a 76.3% chance that it is a member of the Hyades-Pleiades stream of stars that share a common motion through space.
With an estimated age of 4.58 billion years, Kappa Perseii Aa is an evolved G-type giant star with a stellar classification of G9.5 IIIb. It is a red clump giant, which means that it is generating energy at its core through the nuclear fusion of helium. The star has about 1.5 times the mass of the Sun and 9 times the Sun's radius. It radiates 40 times the solar luminosity from its outer atmosphere at an effective temperature of 4,857 K.
Kappa Perseii B is at an angular separation of 44.10 arc seconds along a position angle of 319°, as of 2009.


DT Virginis

DT Virginis, also known as Ross 458 AB, is a binary star in the constellation of Virgo. Both of the stars are low-mass red dwarfs with at least one of them being a flare star. This binary system has a circumbinary planet detected by direct imaging, currently the planetary-mass object with the widest known orbit around a binary star.


32 Vulpeculae

32 Vulpeculae is a single star located around 610 light years away from the Sun in the northern constellation Vulpecula, a few degrees south of the border with Cygnus. It is visible to the naked eye as a faint, orange-hued star with a typical apparent visual magnitude of 5.03. This object is drifting further away from the Earth with a heliocentric radial velocity of +6 km/s.
This is an aging red giant star with a stellar classification of K4 III, having exhausted the supply of hydrogen at its core then expanded to 54 times the Sun's radius. It is a suspected variable of unknown type, with a visual magnitude that has been measured ranging from 4.99 down to 5.06. The star is radiating 708 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,041 K.


NGC 2355

NGC 2355 is an old open cluster in the constellation Gemini.
It is approximately a billion years old and is located about 5,400 light years (ly) from the Solar System and 1,100 ly above the plane of the Milky Way galaxy. At that distance, the angular size of the cluster halo corresponds to a radius of about 23 ly. The core radius is 2.3 ly, and the central component radius is 11 ly.


HD 34790

HD 34790 is a double-lined spectroscopic binary star system in the northern constellation of Auriga. It has a combined apparent magnitude of 5.66, which means it is faintly visible to the naked eye. Based upon observations by the Hipparcos satellite, it is located around 289 light years away. It has a combined stellar classification of A1Vs, matching that of an A-type main sequence star, and shines with 35 times the luminosity of the Sun.
The two stars orbit each other with a period of only 2.15 days and an eccentricity of zero, indicating their orbit is close to circular. They are orbiting sufficiently close to each other that their rotation periods have most likely become tidally locked—meaning they always maintain the same face toward each other.


NGC 244

NGC 244 is a lenticular galaxy located in the constellation Cetus. It was discovered on December 30, 1785 by William Herschel.


Phi Serpentis

Phi Serpentis (φ Ser, φ Serpentis) is a solitary star in the Serpens Caput portion of the equatorial constellation Serpens. Based upon an annual parallax shift of 13.52 mas as seen from Earth, it is located about 241 light years distant. The star is faintly visible to the naked eye with an apparent visual magnitude of +5.55.
At the estimated age of 3.42 billion years, this is an evolved K-type subgiant star with a stellar classification of K1 IV. It has about 1.19 times the mass of the Sun and around 4.2 times the Sun's radius. The star radiates 41.7 times the solar luminosity from its photosphere at an effective temperature of 4,493 K.


NGC 2552

NGC 2552 is a Magellanic spiral galaxy located some 22 million light years away in the faint northern constellation of Lynx. This is a type of unbarred dwarf galaxy, usually with a single spiral arm. It is inclined by 41° to the line of sight from the Earth along a position angle of 229°. The measured velocity dispersion of the stars in NGC 2552 is relatively low—a mere 19 ± 2 km/s. This galaxy forms part of a loose triplet that includes NGC 2541 and NGC 2500, which together belong to the NGC 2841 group.
External links.


NGC 3945

NGC 3945 is a barred lenticular galaxy in the constellation Ursa Major. It was discovered on March 19, 1790 by the astronomer William Herschel.
NGC 3945 has a complex structure, with two concentric bars and a pseudobulge. Unlike classical bulges which are like miniature elliptical galaxies, pseudobulges have features similar to disk galaxies, including a flattened structure and significant rotation. It is classified as a LINER galaxy. The formation history of NGC 3945 is likely quite complex, with the pseudo-bulge being formed gradually from disk material, while bulges (spheroidal components) would have formed from violent merger events.
Unlike galaxies with similar velocity dispersions and luminosities, the central black hole of NGC 3945 has an unusually low mass, estimated to be around . However, it is also possible that NGC 3945 has no central black hole at all.


Psi2 Draconis

Psi2 Draconis is a solitary giant star in the northern circumpolar constellation of Draco, also designated 34 Draconis. It lies just over a degree east of the brighter Psi1 Draconis. Psi2 Draconis has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.45. It is located at a distance of from the Sun based on parallax, but is drifting closer with a radial velocity of −2 km/s.
According to R. O. Gray and associates (2001), the stellar classification of Psi2 Draconis is F2III+; a star that has used up its core hydrogen, cooled, and expanded away from the main sequence. A. P. Cowley and W. P. Bidelman (1979) found a similar class of F3 II-III, with the comment that the spectrum showed "many weak lines". Based on the abundance of iron, the metallicity of this star is much lower than in the Sun. It is about 800 million years old and is spinning with a projected rotational velocity of 50 km/s. The star has double the mass of the Sun but has expanded to 15 times the Sun's radius. It is radiating 448 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 6,925 K.


AC Andromedae

AC Andromedae (AC And) is a variable star in the constellation Andromeda. Its maximum apparent visual magnitude is 10.77, but can be seen fainter down to a magnitude of 11.9.
The nature of AC Andromedae is still not determined. Its light curve shows clearly three radial pulsation modes, the fundamental one with a period of 0.71 days, and the first two overtones of 0.525 and 0.421 days, respectively. It is then unclear if it belongs to the class of RR Lyrae variables or to the one of Delta Scuti variables. Another study points at AC And as an intermediate object between classical Cepheids and Delta Scuti variables. The physical parameters of the star itself would be different depending on which class it belongs to.
By late 2018, the AC Andromedae was classified as rare "triple-mode" subtype of the dwarf cepheid (high-amplitude Delta Scuti variable).


NGC 852

NGC 852 is a barred spiral galaxy located in the Eridanus constellation. It is estimated to be 281 million light-years from the Milky Way and has a diameter of about 110,000 light-years. NGC 852 was discovered on October 27, 1834 by John Herschel.


Pi Piscis Austrini

Pi Piscis Austrini, Latinized from π Piscis Austrini, is binary star system in the southern constellation of Piscis Austrinus, near the eastern constellation border with Sculptor. It has a yellow-white hue and is visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.12. The system is located at a distance of 92 light-years from the Sun based on parallax. Its radial velocity is poorly constrained, but it appears to be drifting closer at a rate of around −6 km/s. Pi Piscis Austrini is moving through the galaxy at a velocity of 16.3 km/s relative to the Sun. Its projected galactic orbit carries it between 24,000 and 37,500 light-years from the center of the galaxy.
This is a single-lined spectroscopic binary system with an orbital period of 178.3 days and an eccentricity of 0.53. The primary component is an F-type main-sequence star with a stellar classification of . In 1965 it was designated a classical Cepheid variable star with a brightness that ranged from 5.10 to 5.12, but is now considered to be (most likely) constant. It displays an infrared excess, suggesting a circumstellar disk is orbiting at a radius of with a mean temperature of 90 K. The cooler secondary companion has a class of F3 V. The system appears to be a source of X-ray emission.


NGC 5824

NGC 5824 is a globular cluster in the constellation Lupus, almost on its western border with Centaurus. Astronomers James Dunlop (1826), John Herschel (1831) and E.E. Barnard (1882) all claim to have independently discovered the cluster. It is condensed and may be observed with small telescopes, but larger apertures are required to resolve its stellar core.


List of stars in Sagitta

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


NGC 438

NGC 438 is an intermediate spiral galaxy of type (R')SAB(s)b: located in the constellation Sculptor. It was discovered on September 1, 1834 by John Herschel. It was described by Dreyer as "pretty faint, small, round, gradually a little brighter middle."


Rho Herculis

Rho Herculis (ρ Her, ρ Herculis) is a double star in the constellation of Hercules. The apparent magnitudes of the components are 4.510 and 5.398, respectively. Parallax measurements published in Gaia Data Release 2 put the system at some 360-390 light-years (111-121 parsecs) away.
The two stars of Rho Herculis are separated by four arcseconds, and are known as Rho Herculis A and B, respectively. A is an A-type giant star, while B is a B-type subgiant star. They are also referred to, rarely, as Rho1 Herculis and Rho2 Herculis. Rho Herculis A is itself a close binary which has been resolved using speckle interferometry, with the two components separated by .
The two visual components have very similar spectral types, between A0 and B9. Rho Herculis A is generally assigned a giant luminosity class, with Rho Herculis B most often considered to be a main sequence star. Rho Herculis A has been considered to be an Ap star, with unusually strong silicon or mercury and manganese absorption lines in its spectrum, but this is now considered to be dubious.


ESO 593-8

ESO 593-8, which is known simply as ‘The Bird’ (also ESO 593-IG 008 or IRAS 19115–212) is group of interacting galaxies located in the constellation of Sagittarius, 650 million light-years away from Earth. It was created by a merger of two spiral galaxies and an irregular dwarf-galaxy. The resulting galaxy has a size similar to the Milky Way: around 100,000 light years. The galaxies were imaged by the Hubble Space Telescope and released in April 2008. The European Southern Observatory has also used the Very Large Telescope to resolve fine details of the galaxy with the use of adaptive optics.


HIP 85605

HIP 85605 is a star in the constellation Hercules with a visual apparent magnitude of 11.03. It was thought to be a M dwarf or K-type main-sequence star potentially from the Sun and possibly a companion of the brighter star HIP 85607, but they are now known to be an optical double. (HIP 85605 is 1,790 ± 30 light years away, and HIP 85607 is 1,323 ± 13 light years away)
The original Hipparcos parallax measurement in 1997 was 202 mas, which would place it 16.1 light-years from the Solar System. In 2007, van Leeuwen revised the number to 147 mas, or 22.2 light-years. With a parallax of 147 mas (0.147 arcseconds), HIP 85605 is unlikely to be one of the 100 closest star systems to the Sun. In 2014, it was estimated that HIP 85605 could approach to about from the Sun within 240,000 to 470,000 years, assuming the then-known parallax and distance measurements to the object were correct. In that case its gravitational influence could have disrupted the orbits of comets in the Oort cloud and caused some of them to enter the inner Solar System.
With the release of Gaia DR2, it was determined that HIP 85605 is actually a much more distant 1790 ± 30 light-years away, and as such will not be passing remotely close to the Sun at any point in time.


NGC 904

NGC 904 is an elliptical galaxy in the constellation Aries. It is estimated to be 244 million light years from the Milky Way and has a diameter of approximately 85,000 ly. NGC 904 was on 13 December 1884 by the astronomer Edouard Stephan.


Chi Ceti

 Chi Ceti (χ Ceti), is the Bayer designation for a double star in the equatorial constellation of Cetus. They appear to be common proper motion companions, sharing a similar motion through space. The brighter component, HD 11171, is visible to the naked eye with an apparent visual magnitude of 4.66, while the fainter companion, HD 11131, is magnitude 6.75. Both lie at roughly the same distance, with the brighter component lying at an estimated distance of 75.6 light years from the Sun based upon an annual parallax shift of 43.13 mass.
The primary, component A, is an evolved K-type giant star with a stellar classification of F3 III. However, Houk and Swift (1999) listed a classification of F0 V, which would match an F-type main sequence star. It displays an infrared excess at a wavelength of 70 μm and thus is a candidate host of an orbiting debris disk.
The common proper motion companion, component B, is a G-type main sequence star with a classification of G3 V. It is a BY Draconis variable with a periodicity of 8.92 days and a variable star designation of EZ Cet.


V357 Carinae

V357 Carinae (a Car, a Carinae) is an astrometric and spectroscopic binary in the constellation Carina. It is approximately 419 light years from Earth. The mean apparent magnitude of the system is +3.43.
Location.
The star appears 46.0' (0.7668°) ENE of Iota Carinae at the heart of the asterism and constellation which is skewed in having bulk of the stars away from the eastern, Canopus prow of the ship and close to the imagined sails of the ship, Vela.
Variability.
V357 Carinae is a probable variable star; its brightness varies from magnitude +3.41 to +3.44 with a period of 6.74 days, which is its orbital period. It was classified as an eclipsing binary in Gaposchkin's original catalogue of variable stars, although the variability was often considered doubtful. It is now thought most likely to be a very shallow eclipsing binary.
System.
V357 Carinae is an astrometric binary, meaning its motion in the sky implies orbital motion about an invisible companion. It is also a single-lined spectroscopic binary, and possibly a triple system. The two closest components orbit each other in 6.74 days, while the observed astrometric motion is much longer.


Pi Draconis

Pi Draconis, Latinized from π Draconis, is a solitary star in the northern circumpolar constellation of Draco. It is visible to the naked eye with an apparent visual magnitude of 4.59. Based upon an annual parallax shift of 14.25 mas as measured from Earth, it is located around 229 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of due to interstellar dust.
With an age of 350 million years, this is an A-type star of stellar classification A2 IIIs, where the luminosity class of III typically indicates an evolved giant star and the 's' means the spectrum displays sharp absorption lines. It is a candidate Am star, meaning there are some chemical peculiarities. The measured angular size is . At the estimated distance of Pi Draconis, this yields a physical size of about 3.2 times the radius of the Sun. It has about 2.70 times the mass of the Sun and is radiating 60 times the solar luminosity from its photosphere at an effective temperature of 9,125 K.
References.
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NGC 6624

NGC 6624 is a globular cluster in the constellation Sagittarius. It was discovered on 24 June 1784 by the astronomer William Herschel. It is given an apparent magnitude of 7.6 to 8.5.
Six pulsars are known in NGC 6624. The first of these to be discovered was PSR J1823-3021A. This globular cluster also contains 4U 1820-30, a low-mass X-ray binary with an orbital period of only 11.5 minutes.
NGC 6624 is visible as a hazy spot with a small telescope, and appears as a star-like object with binoculars. Its core appears significantly condensed. It is located 0.8 degrees southeast of the star Delta Sagittarii, and is about from the Galactic center.


List of stars in Cassiopeia

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


Iota Geminorum

Iota Geminorum (ι Geminorum, ι Gem) is a solitary fourth-magnitude star in the constellation Gemini. In the sky, it forms an isosceles triangle with Castor and Pollux, and is located less than a degree from the 5th magnitude stars 64 and 65 Geminorum.
Nomenclature.
In Chinese, (), meaning "Five Feudal Kings", refers to an asterism consisting of ι Geminorum, θ Geminorum, τ Geminorum, υ Geminorum and φ Geminorum. Consequently, ι Geminorum itself is known as (, .). It has been called by the proper name "Propus", meaning "forefoot" in Latin, but this name is now assigned to η Geminorum.
Properties.
Based upon an annual parallax shift of 27.10 mass, Iota Geminorum lies some 120.4 light years from the Sun. This is an evolved red clump giant star with a stellar classification of G9 III. It is most likely a member of the galactic thin disk population. The star has 1.89 times the mass of the Sun, but has expanded to 10 times the solar radius. It shines with 48 times the Sun's luminosity from its outer atmosphere at an effective temperature of 4,753 K.


Iota Delphini

Iota Delphini (ι Del, ι Delphini) is a star in the constellation Delphinus. It has an apparent magnitude of about 5.4, meaning that it is just barely visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, this star is around 177 light years away from the Sun.
Iota Delphini's spectral type is A1IV, meaning it is an A-type subgiant. Observations of the star's spectrum reveal a periodic Doppler shift. This means that Iota Delphini is a spectroscopic binary with a period of 11 days and an eccentricity of 0.23. However, almost no information is known about the companion star.
Iota Delphini appears to be an Am star, also known as a metallic-line star. These types of stars have spectra indicating varying amounts of metals, like iron. Observations of Iota Delphini's spectrum have showed lower amounts of calcium and higher amounts of iron than usual.


Iota Leporis

Iota Leporis (ι Leporis) is a triple star system in the southern constellation of Lepus. It is visible to the naked eye as a point source of blue-white light with an apparent visual magnitude of 4.45. Based upon an annual parallax shift of 14.07 mas as measured from Earth, the system is located roughly 232 light years from the Sun.
The primary, designated component A, is a B-type main-sequence star with a stellar classification of B7.5 Vn, where the 'n' suffix indicates "nebulous" absorption lines caused by rotation. It is about 94 million years old and has a high rate of spin with a projected rotational velocity of 185 km/s. With an estimated 3.4 times the mass of the Sun, it is radiating 153 times the Sun's luminosity from its photosphere at an effective temperature of around 13,781 K.
There is a close companion that is a source of X-ray emission. Most likely this star has at least 1.05 times the mass of the Sun. The third component, AM Leporis, is a BY Draconis variable of apparent magnitude 9.92, and spectral type G8Ve at an angular separation of 12.7".


Abell 78

Abell 78 is a planetary nebula located in the constellation of Cygnus. It has a fainter halo consisting mostly hydrogen, and an inner elliptical ring that is mostly made of helium.


Gliese 3634

Gliese 3634 (Often shortened to GJ 3634) is a red dwarf star in the Hydra constellation. One planet has been discovered in its orbit, Gliese 3634 b. GJ 3634 is under half the mass and size of the Sun, and is estimated to be at least a billion years younger, and lies near to Earth, with a distance of 19.8 parsecs (64.6 light years). It was targeted by astronomers during an over six-year survey of red dwarfs. The astronomers had recently changed their strategy to search for planets with extremely short orbits so they could narrow down candidates that transited, or crossed in front of, their host stars as seen from the Earth. The Super-Earth GJ 3634 b was the first planet discovered using this new strategy. The planet was confirmed using Doppler spectroscopy, or the observation and extrapolation of data from a recorded Doppler effect in the star's light, but later observations found no transiting pattern. The planet was published by its discoverers on February 8, 2011.
Naming and discovery.
GJ 3634 is named for its location in the Gliese Catalogue of Nearby Stars; a later expansion of the original catalogue was compiled jointly by Gliese and Hartmut Jahreiß. The Third Catalogue, the most recent catalogue, was formed to tag all then-known stars within 25 parsecs of Earth (81.54 light years). GJ 3634 was first catalogued in 1987. The discoverers of GJ 3634 b worked through the High Accuracy Radial Velocity Planet Searcher (HARPS) at the European Southern Observatory's La Silla Observatory in Chile for over six years in search of planets that orbited low-mass red dwarfs. After the discoveries of eleven prior planets, the researchers changed their strategy to search for planets with extremely short orbits. They would first discover the system using the radial velocity method, in which an observed Doppler shift in the star's light would be measured and interpreted; and would then follow up with a search for transits, in which the planet crosses in front of and dims its star as seen from Earth. Radial velocity measurements would help determine the most efficient and time-effective means of observing potential planetary transits.
Radial velocity measurements revealed the existence of a planet with a mass of at least 7 Earths. This planet, GJ 3634 b, became the first planet to be discovered under the new strategy. The team of astronomers then followed up with transit measurements using instruments on the Spitzer Space Telescope; they found that there was most likely no transit event present at the star, but they were able to discover its true mass. GJ 3634 b was published to the journal "Astronomy and Astrophysics" on February 8, 2011.
Characteristics.
GJ 3634 is an M-type red dwarf, a cool, small and dim star that shines with reddish light. It lies in the Hydra constellation. The star is 45% the mass of the Sun, and is 43% the Sun's size. GJ 3634, described by its discoverers as an "intermediately active star," has a luminosity of 0.02, meaning that it releases about 2% of the energy that the Sun radiates. The star is relatively metal-poor; with a metallicity of [Fe/H] -0.10, GJ 3634 has 79% the amount of iron that has been measured in the Sun. The star is younger than the Sun, with an estimated age of at most three billion years.
GJ 3634 has an apparent magnitude of 11.95. Thus, despite its proximity at 19.8 parsecs (64.6 light years) away from the Earth, it cannot be seen with the unaided eye. The star is of a similar distance from Earth as planet-bearing 51 Pegasi, which lies at a distance of 14.7 parsecs (47.95 light years).
Planetary system.
GJ 3634 has one confirmed planet in orbit: GJ 3634 b. The planet was called a Super-Earth by its discoverers because of its mass, which was deduced to be 8.4 times that of Earth's and 0.02 times that of Jupiter's. GJ 3634 b has an extremely short orbital period, orbiting GJ 3634 every 2.64561 days. The planet orbits near to its star, and is at an average distance of .0287 AU away. It has an orbital eccentricity of 0.08, meaning that its orbit is very circular.
The initial study into the system suggests that a second planet in the inner system is unlikely. The discoverers of GJ 3634 b, however, noted the signal of a secondary body of an unknown nature that most likely orbits GJ 3634 every 200 days with a mass that is at most double that of Neptune.


NGC 6578

NGC 6578 is a planetary nebula located in Sagittarius. It is magnitude 13.5 with diameter 8 arc seconds. It has a 16th magnitude central star. It is seen near the star 16 Sagittarii.


LSS 4067

LSS 4067, also known as CD−38°11748, is an O-type blue supergiant star located in the constellation Scorpius, very close to the galactic plane. It is part of the open cluster HM 1, although its distance is not well known; it may be anywhere between 9,500 and 12,700 light years (2900 to 3900 parsecs) away from the Earth. Despite being a blue supergiant, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands. Without the extinction, it is estimated that LS 4067 would be 5.8 magnitudes brighter, a naked eye star with an apparent magnitude of 5.3.
Although the Gaia Data Release 2 parallax for LS 4067 is negative, a likely distance can be calculated from it. The star is thought to be between 8,202 and away, statistically most likely at . It was catalogued as a member of the faint cluster Havlen-Moffat No. 1, but is no longer thought to be a member. The cluster lies about .
LSS 4067 has an absolute bolometric magnitude of −11.4, making it one of the most luminous stars known. Indeed, many of the hottest and most luminous stars known are O-type supergiants, or Wolf-Rayet stars. LSS 4067 has an unusual spectrum, with various emission lines including N III and He II emission lines, thus the "f" in its spectral type. Because of this unusual spectrum, classifying the star or deducing its properties has proved relatively difficult: for example, the effective temperature is predicted to be too cool and the surface gravity too high.


V473 Lyrae

V473 Lyrae is a variable star in the constellation Lyra. It is an unusual Classical Cepheid variable with a visual range of 5.99 to 6.35.
Discovery.
V473 Lyrae is a faint naked eye star, but its brightness variations were not reported until 1968. It was noted to be possibly variable, then examined as a possible δ Sct variable. It was confirmed as variable but the variations were considered semi-regular and so it was not catalogued as a δ Sct variable.
In 1979, brightness variations were again noticed and V473 was listed as a short-period Cepheid, although the period was thought to be 3.04 days. The correct period was found a few years later at 1.49078 days, at the time the shortest known period for a galactic Cepheid. Unusual periodic variations in the pulsation amplitude were also noticed, similar to the Blazhko effect in RR Lyrae variables.
Pulsations.
The unusually short period of V473 Lyr is caused by pulsations in the second overtone and the fundamental pulsation period would be three times as long. The amplitude variations have an approximate period of 1,205 days, and there is a secondary modulation with a period of 5,300 days.
Companion.
V473 Lyrae has a faint companion. Although the two stars are separated by 15", the companion is 15th magnitude and so faint that it is difficult to detect next to the naked eye primary. At the distance of V473 Lyrae, the separation corresponds to 8,300 astronomical units.
X-rays.
X-rays have been detected from V473 Lyrae during a survey looking for x-rays from young main sequence companions to Cepheid variables. However, the x-rays in this case appear to originate from the Cepheid itself, not from the companion. There may be a closer unseen companion or the x-rays may have another cause.


NGC 736

NGC 736 is an elliptical galaxy in the constellation Triangulum. It is an estimated 200 million light years from the Milky Way and has a diameter of approximately 85,000 light years. NGC 736 was discovered on September 12, 1784 by the German-British astronomer William Herschel.


59 Aurigae

59 Aurigae, often abbreviated as 59 Aur, is a star in the constellation Auriga. Its baseline apparent magnitude is 6.1, meaning it can just barely be seen with the naked eye as a dim, yellow-white hued star. Based on parallax measurements, it is located about away from the Sun.
This object is a Delta Scuti variable, meaning it varies in luminosity due to pulsations on its surface, ranging in magnitude from 5.94 down to 6.14 with a period of . For that reason, it has been given the variable star designation OX Aurigae. The star's spectrum matches that of an F-type main-sequence star and it has a spectral type of F2V. It has 2.5 times the mass of the Sun and 5.7 times the Sun's radius. 59 Aurigae is thought to be around 700 million years old, and is radiating 64 times the Sun's luminosity from its photosphere an effective temperature of 6,808 K.


Beta Comae Berenices

Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices. It is located at a distance of about from Earth. The Greek letter beta (β) usually indicates that the star has the second highest visual magnitude in the constellation. However, with an apparent visual magnitude of 4.3, this star is actually slightly brighter than α Comae Berenices. It can be seen with the naked eye, but may be too dim to be viewed from a built-up urban area.
The star is similar to the Sun, being only slightly larger and brighter in absolute magnitude. It has a stellar classification of G0 V, compared to G2 V for the Sun. The effective temperature of the outer envelope is 5,936 K, giving it a yellow hue of a G-type star. In terms of age it is younger than the Sun, being about 3 billion years old.
Observations of short term variations in the chromatic activity suggest that the star undergoes differential rotation, with a rotation period of about 11–13 days. Its surface has a measured activity cycle of 16.6 years, compared to 11 years on the Sun. It may also have a secondary activity cycle of 9.6 years. At one time it was thought that this star might have a spectroscopic companion. However, this was ruled out by means of more accurate radial velocity measurements. No planets have yet been detected around it, and there is no evidence of a dusty disk.
The habitable zone for this star, defined as the locations where liquid water could be present on an Earth-like planet, is 0.918–1.96 AU, where 1 AU is the average distance from the Earth to the Sun.


V372 Carinae

V372 Carinae is a single star in the southern constellation of Carina. Located around 1300 light-years distant. It shines with a luminosity approximately 1742 times that of the Sun and has a surface temperature of 14132 K. It is a Beta Cephei variable.


K2-239

K2-239 (also designated EPIC 248545986) is a small red dwarf star in the constellation Sextans, about 49 parsecs (160 light-years) away from Earth. Observed by the Kepler Space Telescope during Campaign 14 of its K2 "Second Light" mission, it was found to have three hot, likely rocky Earth-sized planets in orbit around it.
Stellar characteristics.
K2-239 is a small red dwarf star of spectral class M3V. It is 40% the mass and 36% the radius of the Sun with just 0.016 times the luminosity. It has a temperature of 3420 K and its age is unknown. For comparison, the Sun has a temperature of 5778 K and is 4.5 billion years old. K2-239 has a visual magnitude of 14.549, far too dim to see with the unaided eye. It is also one of the closer systems found by Kepler, only about 160 light-years away from Earth.
Planetary System.
K2-239 has a system of three small, Earth-sized planets in a tight 2:3:4 orbital resonance chain. All of them are between 1.0 and 1.1 times the size of Earth, meaning they are very likely to be rocky. The discovery team estimated their masses to range from 0.9 to 1.4 , consistent with a rocky composition for each of the planets. Due to their proximity to K2-239 they are all hot; however, because the host star is just 1.6% as luminous as the Sun, they are much cooler than if they were placed around our Sun. For albedoes of 0 they would have equilibrium temperatures of for K2-239b, for K2-239c, and for K2-239d. None of them are cool enough to host liquid water or be considered potentially habitable.


Theta2 Orionis

Theta2 Orionis (θ2 Ori) is a multiple star system in the constellation Orion. It is a few arc minutes from its more famous neighbour the Trapezium Cluster, also known as θ1 Orionis.
Components.
θ2 Orionis consists of three stars in a line, each about an arc-minute from the next. In addition to the well-known three stars, the Washington Double Star Catalog confusingly lists a component D which is actually θ1 Orionis C.
There is one other star brighter than 10th magnitude in the region. V1073 Orionis is a B9.5 Orion variable that forms an equilateral triangle with θ2 Ori B and C.
Bizarrely, θ2 Orionis C has a second entry in the Washington Double Star Catalog under the name S490. The companion is 10th magnitude and actually lies between θ2 Ori B and V1073 Ori.
θ1 Orionis, the well known Trapezium cluster, is only 2 arc minutes away from θ2 Orionis A. Despite the names, θ2 Orionis A is marginally brighter than the brightest star in the Trapezium. The Catalog of Components of Double and Multiple Stars includes the stars of θ1 and θ2 Ori within the same system of 13 components.
There are dozens of much fainter stars in the same field, many of them pre-main-sequence stars still forming from the Orion Molecular Cloud Complex.
Properties.
The primary component A appears as a 5th magnitude O class subgiant over 100,000 times as luminous as the sun. The spectral type suggests it is evolving away from the main sequence, although it is thought to be less than 2 million years old. The spectral peculiarities may be related to close companions or could be caused by the extreme youth of the star.
The 6th magnitude component B is an early B main sequence star nearly 30,000 K and over 10,000 times the luminosity of the sun.
Component C is another B class main sequence star, but cooler and less than a thousand times the luminosity of the sun.
θ2 Orionis A system.
θ2 Orionis A is itself a triple star system. Its spectral lines were seen to change position periodically, indicating orbital motion. The first orbit was derived in 1924, indicating a period of 21 days. and a rather eccentric orbit.
Speckle interferometry has resolved a companion about 0.3" away, around 147 AU. High resolution spectroscopy shows that there is an even closer companion, only about 0.47 AU from the primary, for a total of three stars. Both companions are thought to be early A or late B with masses of . This helps to explain the high mass and visual luminosity for an O9.5 star at this distance. The three stars together have nearly the same mass as the O5.5 θ1 Orionis C and visually are even brighter.
θ2 Orionis A also shows unexplained rapidly variable x-ray emission. The x-rays cannot be explained standard mechanisms such as colliding winds or coronal emissions from an unseen companion.


Chi Eridani

χ Eridani (Latinised as Chi Eridani) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.70. The distance to this system, as determined using the parallax method, is around 58 light years. The pair had an angular separation of 5.0 arcseconds as of 1994. This corresponds to a projected separation of around 128 AU.
The primary component is an evolving G-type subgiant star with a stellar classification of G8 IV. It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius. The star shines with 10 times the solar luminosity from its outer atmosphere at an effective temperature of 5,115 K. Unusually for a star of this class, it shows a photometric variability of 0.04 in magnitude, which may be due to a previous mass transfer from the secondary companion, or else from an undiscovered third companion.
The companion is about 7 magnitudes fainter than the primary and may be the source of the X
-ray emission from this system. This emission has a luminosity of .


Chi Leonis

Chi Leonis, Latinized from χ Leonis, is a double star in the constellation Leo. It is visible to the naked eye with an apparent visual magnitude of 4.63. The distance to this star, as determined using parallax measurements, is around 95 light years. It has an annual proper motion of 346 mas.
This is most likely a binary star system. The primary component is an evolved, F-type giant star with a stellar classification of F2III-IVv. It has an estimated 162% of the Sun's mass and nearly twice the Sun's radius. The companion is a magnitude 11.0 star at an angular separation of 4.1″ along a position angle of 264°, as of 1990.


NGC 3079

NGC 3079 is a barred spiral galaxy about 50 million light-years away, and located in the constellation Ursa Major. A prominent feature of this galaxy is the "bubble" forming in the very center (see picture below). The Supermassive black hole at the core has a mass of .
Center Bubble.
The bubble forming in the center of NGC 3079 is believed to be about 3000 light-years wide and to rise more than 3500 light-years above the disc of the galaxy. It is speculated that the bubble is being formed by particles streaming at high speeds, which were in turn caused by a large burst of star formation. This current bubble is thought to have been created about one million years ago, and computer modeling suggests that there is an ongoing cycle of forming bubbles, with a new bubble forming approximately every 10 million years.


List of stars in Pyxis

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


NGC 654

NGC 654 is an open cluster in the constellation Cassiopeia. It was discovered by William Herschel in 1787. With apparent magnitude 6.5, it can be observed by binoculars. It is located 2,5° northeast of the star Delta Cassiopeiae. In the same low power field can also be seen the open clusters NGC 663 and NGC 659. It surrounds a 7th magnitude yellowish star, an F5Ia supergiant, which is a possible member of the group.
It is 2,400 parsec away. It is a very young cluster, aged approximately 15 million years, but it can be as old as 40 million years, with a time spread of star formation of at least ∼20 Myr. The central region of the cluster shows less reddening than the rest of the cluster. An explanation given is the fact that between the solar system and the cluster lie two dust layers, one at 200pc and one more at 1Kpc. Behind the cluster is one more dust layer. The cluster has approx. 80 members. The earliest spectral type is around B0 and members of the cluster are also a few luminous stars, like HD 10494, F5Ia. Also, in the cluster have been found three Be stars.
NGC 654 is assumed to form part of the stellar association Cassiopeia OB8, that is located in the Perseus arm of the Milky Way, along with the open clusters M103, NGC 663, NGC 659, and some supergiant stars scattered between them, all of them having similar ages and distances.


NGC 6558

NGC 6558 is a globular cluster, located about 24,000 light years away in the constellation Sagittarius. Its apparent magnitude is about 11 and its apparent diameter is about 10 arcminutes. The globular cluster was discovered in 1784 by the astronomer William Herschel with his 18.7-inch telescope and the discovery was later catalogued in the New General Catalogue.
It is located 1.5 degrees south-southeast of Gamma2 Sagittarii.


NGC 2298

NGC 2298 is a globular cluster in the southern constellation of Puppis. Discovered by James Dunlop on May 30, 1826, it is probably a former member of the disputed Canis Major Dwarf galaxy.
The cluster is being disrupted by the galactic tide, trailing a long tidal tail.


Alpha Piscium

Alpha Piscium (α Piscium) is a binary star system in the equatorial constellation of Pisces. Based upon parallax measurements made by the Hipparcos spacecraft, it is about from the solar system.
The two components are designated Alpha Piscium A (officially named Alrescha, the traditional name of the system) and B.
Nomenclature.
"α Piscium" (Latinised to "Alpha Piscium") is the star's Bayer designation. The designations of the two components as "Alpha Piscium 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).
The system bore the traditional name "Alrescha" (alternatively "Al Rescha", "Alrischa", "Alrisha") derived from the Arabic الرشآء "al-rishā’" "the cord" and less commonly "Kaitain" and "Okda", the latter from the Arabic عقدة "ʽuqdah" "knot" (see Ukdah. 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 "Alrescha" for the component Alpha Piscium A on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Outer Fence", refers to an asterism consisting of Alpha Piscium, Delta Piscium, Epsilon Piscium, Zeta Piscium, Mu Piscium, Nu Piscium and Xi Piscium. Consequently, the Chinese name for Alpha Piscium itself is (, ).
Properties.
Alpha Piscium comprises a close binary with angular separation of presently 1.8" between the components. The main star or primary (Alpha Piscium A) is of magnitude +4.33 and spectral type A0p, while the companion or secondary (Alpha Piscium B) is magnitude 5.23 and belongs to spectral class A3m. The two stars take more than 3,000 years to orbit one another and they will make their closest approach to each other around 2060. One or both of the stars may be a spectroscopic binary as well. The stars have masses of 2.55 and 2.64 solar masses respectively and shine with a total luminosity of 55 and 63 times that of the Sun.
Alpha Piscium is catalogued as an α2 Canum Venaticorum variable, a type of variable star where the brightness changes are caused by the rotation of the star. The brightness varies by about 1/100th of a magnitude, identified from Hipparcos photometry. The primary component is thought to be the source of the variations, and it has a period of 0.845 days which corresponds to the rotation period of the star. Variations with a period of 6.65 days have also been identified in the variations.
Long-exposure observation.
Stars that can set (not in a circumpolar constellation for the viewer) culminate at midnight – where viewed away from any polar region experiencing midnight sun – when at opposition, meaning they can be viewed from dusk until dawn. This applies to α Piscium on 21 October, in the current astronomical epoch.
Half of the year from this date, 22 April, the star will be at conjunction above or below, the sun – apart by the star's declination (angle set out in table, right). The nearby days and months have most of the star's risen time during daylight.


Epsilon Coronae Borealis

Epsilon Coronae Borealis, Latinized from ε Coronae Borealis, is a multiple star system in the constellation Corona Borealis located around 230 light-years from the Solar System. It shines with a combined apparent magnitude of 4.13, meaning it is visible to the unaided eye in all night skies except those brightly lit in inner city locations. It is an orange giant around 1.7 times as massive as the Sun of spectral type K2III, which has exhausted its core fuel supply of hydrogen and swollen to 21 times the Sun's diameter and 151 times its luminosity. That is, Epsilon Coronae Borealis's diameter is about one-quarter of Mercury's orbit. Its surface temperature has been calculated to be 4365 ± 9 K, or 4406 ± 15 K. It is thought to be around 1.74 billion years old.
Epsilon Coronae Borealis B is a companion star thought to be an orange dwarf of spectral types K3V to K9V that orbits at a distance of 135 astronomical units, completing one orbit every 900 years.
A faint (magnitude 11.5) star, 1.5 arc minutes away, has been called Epsilon Coronae Borealis C although it is only close by line of sight and is unrelated to the system.
The ε CrB star system's radial velocity was observed over seven years from January 2005 to January 2012, during which time a 'wobble' with a period of around 418 days was recorded. This has been calculated to be a planet around 6.7 times as massive as Jupiter orbiting at a distance of 1.3 astronomical units with an eccentricity of 0.11.
Epsilon Coronae Borealis lies one degree north of (and is used as a guide for) the variable T Coronae Borealis.


Psi Leonis

ψ Leonis (Latinised as Psi Leonis, abbreviated to ψ Leo or psi Leo), is a solitary star located in the zodiac constellation of Leo, to the east-northeast of Regulus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.38. Based upon stellar parallax measurements, it is located around 95 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an absorption factor of 0.3 due to interstellar dust.
Psi Leonis is an evolved red giant star with a stellar classification of M2 IIIab. It shines with a luminosity over 900 times that of the Sun from a relatively cool outer atmosphere that has an effective temperature of 3,756. It is a suspected variable star with a measured brightness variation of 0m.018. Psi Leonis has a magnitude 11.63 visual companion at an angular separation of 281.60 arcseconds along a position angle of 139°, as of 2000.


NGC 427

NGC 427 is a spiral galaxy of type (R)SB(r)a: located in the constellation Sculptor. It was discovered on September 25, 1834 by John Herschel.
It was described by Dreyer as "3 very small (faint) stars with nebulosity (?)."


Delta Sextantis

Delta Sextantis (δ Sex, δ Sextantis) is a solitary star in the equatorial constellation of Sextans. With an annual parallax shift of 10.13 mas, it lies at a distance of around 322 light years from the Sun. This star is faintly visible to the naked eye, having an apparent visual magnitude of +5.25. According to the Bortle scale, that means it can be viewed from dark suburban skies.
This is a B-type main sequence star with a stellar classification of B9.5 V; just shy of being a cooler A-type star. It is estimated to have 2.6 times the Sun's mass and 2.3 times the radius of the Sun. It is 146 million years old, with a projected rotational velocity of 152 km/s. The star radiates 82 times the solar luminosity from its outer atmosphere at an effective temperature of 10,899 K.


Beta Cancri

Beta Cancri (β Cancri, abbreviated Beta Cnc, β Cnc), also named Tarf , is the brightest star in the zodiacal constellation of Cancer. It has an apparent visual magnitude of +3.5 and an absolute magnitude of −1.2. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 290 light-years distant from the Sun. An exoplanet, designated Beta Cancri b, is believed to be orbiting the star.
Beta Cancri has a companion listed and together they are designated WDS J08165+0911. As the primary, Beta Cancri bears the designation WDS J08165+0911A. The companion is designated WDS J08165+0911B.
Nomenclature.
"β Cancri" (Latinised to "Beta Cancri") is the star's Bayer designation. WDS J08165+0911A is its designation in the Washington Double Star Catalog.
The star bore the traditional name of "Al Tarf" (anglicized as "Altarf"), which can be translated from the Arabic as "end" or "edge". 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 "Tarf" for Beta Cancri on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
Properties.
Beta Cancri is an orange K-type giant, about 50 times the radius of the Sun. It is a Barium star, a type of cool giant showing enhanced abundances of Barium. It is also suspected to vary slightly in brightness.
The companion is a red dwarf of the fourteenth magnitude. From its angular distance of 29 arcseconds, the companion's distance from Beta Cancri is estimated at some 2600 AU, with an orbital period of 76,000 years.
Planet.
In 2014 evidence was presented of a planet orbiting Beta Cancri. Using radial velocity data from repeated observations of the star, the planet is estimated to have a minimum mass of approximately 7.8 times that of Jupiter, and an orbital period of 605 days.


AZ Canis Minoris

AZ Canis Minoris is a variable star in the equatorial constellation of Canis Minor. It is just visible to the naked eye in good viewing conditions as a dim, white-hued star with an apparent visual magnitude of around 6.46. The star is located around 500 light years away from the Sun based on parallax, and is drifting further away with a radial velocity of +15 km/s. No evidence has been found for a companion to this star, although in the past it has been reported as a binary star system.
This star has a stellar classification of A5 IV, matching an A-type subgiant star. The variable nature of this star was discovered in 1970 at Kitt Peak Observatory. It is a monoperiodic Delta Scuti variable with a cycle period of and an amplitude of 0.060 in visual magnitude; ranging from a peak magnitude of 6.44 down to 6.51. AZ Canis Minoris is nearly a billion years old with a projected rotational velocity of 44 km/s. It has 1.9 times the mass of the Sun and 3.8 times the Sun's radius. The star is radiating 48 times as much luminosity as the Sun from its photosphere at an effective temperature of 7,783 K.