Omicron Puppis

Omicron Puppis (ο Puppis) is candidate binary star system in the southern constellation of Puppis. It is visible to the naked eye, having a combined apparent visual magnitude of +4.48. Based upon an annual parallax shift of 2.30 mas as seen from Earth, it is located roughly 1,400 light years from the Sun.
This is a suspected close spectroscopic binary system. The spectrum varies with a periodicity of 28.9 days, and a helium emission component shows a radial velocity variation that matches the period. The properties indicate it may be a φ Per-like system with a Be star primary and a hot subdwarf companion of type sdO. If this is the case, then the pair have a circular orbit with a period that matches the variability. The close-orbiting pair may have undergone interaction in the past, leaving the subdwarf stripped down and the primary star spinning rapidly.
ο Puppis is slightly variable. The General Catalogue of Variable Stars lists it as a possible Be star with a magnitude range of 4.43 - 4.46. The International Variable Star Index classifies it as a Lambda Eridani variable.
Naming.
The correct Bayer designation for ο Puppis has been debated. Lacaille assigned one Greek letter sequence for the bright stars of Argo Navis. These Lacaille designations are now shared across the three modern constellations of Carina, Puppis, and Vela so that the same Greek letter is not usually found in more than one of the three. However, ο (omicron) is commonly used for stars in both Puppis and Vela. Some authors contend that Lacaille actually assigned a Latin lower case 'o' to this star, while others suggest that ο Velorum should actually be a lower case 'o'. In the "Coelum Australe Stelliferum" itself, this star is labelled (Latin) o Argus in puppi (Pouppe du Navire in the French edition), while ο Velorum is labelled ο (omicron) Argus (du Navire in the French edition).
In Chinese, (), meaning "Bow and Arrow", refers to an asterism consisting of ο Puppis, δ Canis Majoris, η Canis Majoris, HD 63032, HD 65456, k Puppis, ε Canis Majoris, κ Canis Majoris and π Puppis. Consequently, ο Puppis itself is known as (, .)


Psi Centauri

Psi Centauri, which is Latinized from ψ Centauri, is a binary star system in the southern constellation of Centaurus. It is visible to the naked eye with a baseline apparent visual magnitude of +4.05. The distance to this system is approximately 259 light years based on parallax. The radial velocity is poorly constrained, but it appears to be slowly drifting away from the Sun at the rate of +2 km/s.
This is a detached eclipsing binary system with the secondary eclipse being total. The pair are orbiting each other with a period of 38.81 days and an eccentricity of 0.55. The brightness of the system dips by 0.28 and 0.16 magnitude during the two eclipses per orbit. The system displays an infrared excess at a wavelength of 60 μm, indicating the presence of a circumstellar debris disk with a temperature of 120 K, orbiting at a distance of 64 AU.
The pair have a combined stellar classification of A0 IV, matching a white-hued A-type subgiant. The two components appear to be at different evolutionary stages. Both have high rotation rates, with projected rotational velocities over 120 km/s. The primary has 3.6 times the Sun's radius while the secondary is 1.8 times. The primary showed evidence of pulsational behavior with 1.996 and 5.127 cycles per day, which suggests it is a slowly pulsating B star. But this remains unconfirmed as of 2017, and the finding may instead be the result of instrumental error.


A Serpentis

The Bayer designation A Serpentis is shared by two stars in the head of the constellation Serpens:


HR 3803

HR 3803 or N Velorum (N Vel) is a 3rd-magnitude star on the border between the southern constellations Carina and Vela. Based upon parallax measurements, it is approximately from Earth. It is an orange-hued K-type giant star and has twice the mass of the Sun. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of HR 3803, this yields a physical size of about 29 times the radius of the Sun.
In 1752, French astronomer Nicolas Louis de Lacaille divided the former constellation Argo Navis into three separate constellations, and then referenced its stars by extending Bayer's system of star nomenclature; this star was given the designation "N Velorum". In 1871 Benjamin Apthorp Gould discovered this star to be variable, but this occurred prior to the standardization of variable star nomenclature by German astronomer Friedrich Wilhelm Argelander during the nineteenth century, so it does not fall into the standard range of variable star designations.
References.
\end{align}</math></ref>


Gliese 686

Gliese 686 (GJ 686 / HIP 86287 / LHS 452) is a star in the constellation of Hercules, with an apparent magnitude +9.577. Although it is close to the Solar System - at 26.5 light years - it is not the closest known star in its constellation, since Gliese 661 is 20.9 light years away. The closest system to this star is the bright μ Herculis, at 4.5 light years. They are followed by GJ 1230 and Gliese 673, at 7.2 and 7.6 light years respectively.
Gliese 686 is one of the many red dwarfs in the Solar System neighborhood with a spectral type of M1V, and has an effective temperature of about 3600 K. Its brightness in the visible spectrum is equal to 0.82% of that of the Sun, while its total luminosity is equivalent to 2.7% that of the Sun, since a significant amount of the radiation emitted by these stars is infrared invisible light. Considering only this last parameter, Gliese 686 is considerably brighter than other known red dwarfs; thus, it is 6.5 times more luminous than Ross 154 and 15 times more than Proxima Centauri, the closest star to the Solar System.
Gliese 686 has a radius approximately equal to half the solar radius. Its projected rotation speed is 2.5 km / s, its rotation period being equal to or less than 10.3 days. It has a metallic content lower than that of the Sun; various studies estimate its index metallicity between -0.25 and -0.44. It has an approximate mass between 45% and 49% of the solar mass and is a star with characteristics comparable to that of Lacaille 9352.
Planetary system.
Gliese 686 has one known super-Earth planet detected by radial velocity.


R Cancri

R Cancri is a Mira variable in the constellation Cancer. Located approximately distant, it varies between magnitudes 6.07 and 12.3 over a period of approximately 357 days.


83 Ursae Majoris

83 Ursae Majoris is a candidate binary star system in the northern circumpolar constellation of Ursa Major. This is a semiregular variable star, like Mira; for that reason it has been given the variable star designation IQ Ursae Majoris. It ranges in brightness from apparent visual magnitude 4.69 to 4.75. Percy and Au (1994) identified it as a small amplitude red variable with an irregular behavior, having a characteristic time scale of 20 days. Based upon an annual parallax shift of , it is located roughly 520 light years from the Sun. The system is moving closer with a heliocentric radial velocity of −18.6 km/s.
The visible component is an evolved red giant with a stellar classification of M2 III. It is a marginal barium star, showing an enhanced abundance of s-process elements in its outer atmosphere. This material may have been acquired during a previous mass transfer from a now white dwarf companion, or self-enriched by a dredge-up during the asymptotic giant branch process.


5 Persei

5 Persei is a star in the northern constellation of Perseus located around away from the Sun. It is part of the Perseus OB1 stellar association and lies near the Double Cluster. This object is near the lower limit of visibility to the naked eye with an apparent visual magnitude of +6.35. It is moving closer to the Earth with a heliocentric radial velocity of −34 km/s.
This is a blue supergiant of spectral type B5 Ia; a massive star that has used up its core hydrogen and expanded into a very luminous star. It has an effective temperature around 15,000 K and is radiating 83,000 times the Sun's luminosity. Several studies of 5 Persei have detected possible small amplitude variations. In 1983, an amplitude of 0.045 magnitudes was measured with a possible period of eight days. An analysis of Hipparcos photometry showed an amplitude of 0.0168 magnitudes and a period of 2.65 days. The statistical signal was strong enough for the variability to be very likely, but 5 Persei has not formally been catalogued as a variable star.
5 Persei has two nearby companions, a 12th magnitude star 5.7 arc-seconds away and a 13th magnitude star one arc-minute away.


20 Leonis Minoris

20 Leonis Minoris is a binary star system in the northern constellation of Leo Minor. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.4. Based upon an annual parallax shift of 66.46 mas, it is located 49 light years from the Sun. The star has a relatively high proper motion and is moving away from the Sun with a radial velocity of +56 km/s. The system made its closest approach about 150,000 years ago when it came within .
The primary member of this system is a G-type main-sequence star with a stellar classification of . It has 12% more mass and a 25% larger radius than the Sun. The star is about seven billion years old and is spinning with a rotation period of 10.6 days. The small companion is an active red dwarf star that has a relatively high metallicity. The two stars are currently separated by 14.5 arc seconds, corresponding to a projected separation of 2016 AU.
In 2020, a candidate exoplanet was detected orbiting 20 Leonis Minoris (HD 86728). With a minimum mass of 0.032 (10.2 ) and an orbital period of 31 days, this would most likely be a hot Neptune.


Delta Geminorum

Delta Geminorum (δ Geminorum, abbreviated Delta Gem, δ Gem), formally named Wasat , is a triple star system in the constellation of Gemini.
Nomenclature.
"δ Geminorum" (Latinised to "Delta Geminorum") is the system's Bayer designation.
It bore the traditional name "Wasat", which derives from the Arabic word for "middle". 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 "Wasat" for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
In Chinese, (), meaning "Celestial Wine Cup", refers to an asterism consisting of Delta Geminorum, 57 Geminorum and Omega Geminorum. Consequently, Delta Geminorum itself is known as (, .). From this Chinese name, the name "Ta Tsun" has appeared.
Properties.
Delta Geminorum is a subgiant star with the stellar classification F0 IV. It is about distant. This star has 1.57 times the mass of the Sun and is rotating rapidly with a projected rotational velocity of . The estimated age is 1.6 billion years.
It has an apparent visual magnitude of +3.53, allowing it to be seen with the naked eye. It is 0.18 degree south of the ecliptic so it is occasionally occulted by the Moon and, rarely, by a planet; and is eclipsed by the sun from about 10-12 July. Thus the star can be viewed the whole night, crossing the sky, in mid-January. The last occultation by a planet was by Saturn on June 30, 1857, and the next will be by Venus on August 12, 2420. In 1930, the dwarf planet Pluto was discovered about 0.5° to the east of this star by American astronomer Clyde Tombaugh.
Delta Geminorum is a triple star system. The inner components form a spectroscopic binary with a period of 6.1 years (2,238.7 days) and an orbital eccentricity of 0.3530. A cooler class K companion is not apparent to the naked eye but clearly visible in a small telescope. It orbits the inner pair with a period of 1,200 years and an eccentricity of 0.11. Although according to its radial velocity is away from the Sun, it is actually approaching the Solar System. In about 1.1 million years, it will make its closest approach at a separation of roughly .


HD 63032

c Puppis, also known as HD 63032 and HR 3017, is a spectroscopic binary star in the constellation Puppis. Its apparent magnitude is 3.61. Located around distant, the primary is an orange-red bright giant or supergiant of spectral type K2.5Ib-IIa or K5IIa, while the secondary, discovered in 1983, is a blue main-sequence star of spectral type B9V. The system is the brightest member of the open cluster NGC 2451, over two magnitudes brighter than every other star in the cluster. As the turnoff point of the cluster is currently around B7, the parameters of the system fit with cluster membership.


NGC 2546

NGC 2546 is an open cluster in the constellation Puppis, discovered by Abbe Lacaille in 1751-1752 from South Africa.


E Carinae

The Bayer designations e Carinae and E Carinae are distinct and the designation e Carinae is shared by two stars in the constellation Carina:
See also.
ε Carinae


Tau Hydrae

The Bayer designation Tau Hydrae (τ Hya, τ Hydrae) is shared by two star systems in the equatorial constellation of Hydra. The two stars are separated by 1.74° in the sky.
The stars τ1 Hya and τ2 Hya, along with ι Hya and the 5th‑magnitude 33 Hya (A Hydrae), were Ptolemy's Καμπή (Kampē); but Kazwini knew them as ʽUḳdah, the Knot. According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Uḳdah" were the title for four stars: τ1 Hya as "Uḳdah I", τ2 Hya as "Uḳdah II", 33 Hya as "Uḳdah III" and ι Hya as "Uḳdah IV"
In Chinese, (), meaning "Star (asterism)", refers to an asterism consisting of τ1 and τ2 Hydrae, Alphard, ι Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. Consequently, τ1 and τ2 Hydrae are known as (, ) and (, ) respectively.


Lupus-TR-3b

Lupus-TR-3b is an extrasolar planet orbiting the star Lupus-TR-3 (a K-type main sequence star approximately 8,950 light-years away in the constellation Lupus). The planet was discovered in 2007 by personnel from the Harvard-Smithsonian Center for Astrophysics observing at the Siding Spring Observatory in Australia, by the transit method.
The planet has four-fifths the mass of Jupiter, nine-tenths the radius, and has density of 1.4 g/cm³. This planet is a typical “Hot Jupiter” as it orbits at 0.0464 AU distance from the star, taking 3.9 days to orbit. It is currently the faintest ground-based detection of a transiting planet.


HO Telescopii

HO Telescopii is an eclipsing binary star system located in the southern constellation of Telescopium. The maximum apparent visual magnitude of 8.22 is too faint to be visible to the naked eye. The system is located at a distance of approximately 910 light years based on parallax. The combined stellar classification of the system is A7III(m), matching an evolved A-type star that is possibly metallic-lined. The system is around 1.1 billion years old and consists of two stars of similar mass and size.
The variability of this system was discovered by W. Strohmeier, R. Knigge, and H. Ott in 1965. It is a detached binary system with both components filling three-fourths of their respective Roche lobes. Their orbital period is  days with a circularized orbit, and the orbital plane is inclined by 83° to the line of sight from the Earth; close to edge-on. As a consequence, they form an Algol-like eclipsing binary with a magnitude decrease of 0.51 during the primary eclipse and 0.45 during the secondary eclipse.


Kepler-89e

Kepler-89e, also known as KOI-94e, is an exoplanet in the constellation of Cygnus. It orbits Kepler-89.
Physical properties.
It is a type III planet, making it cloudless and blue, making it look like a larger version of Uranus and Neptune. It has a mass around 35 times that of Earth. It has a similar density to Saturn, 0.60 g/cm3, giving it a radius 6.56 times that of the Earth. It orbits an F-type main-sequence star at a distance of 0.305 astronomical units (au), with a period of 54.32031 days, making its orbit smaller than that of Mercury's. It has a very low eccentricity of 0.019. It has a temperature of 584 K.
Kepler-89e orbits the star Kepler-89. Kepler-89 has a mass of 1.18 solar masses, and a radius of 1.32 solar radii. It is 3.3 billion years old, younger than the Sun, making its planets about 3,000,000,000 years old (3 Gyr). It has a temperature of 6,210 K, making it appear bright yellowish-white.


NGC 6355

NGC 6355 is a globular cluster located in the constellation Ophiuchus. It is designated as GCL in the galaxy morphological classification scheme and was discovered by the German-born British astronomer William Herschel on 24 May 1784. It is at a distance of 31,000 light years away from Earth.<ref name="NASA/IPAC"></ref>


Psi Serpentis

Psi Serpentis (ψ Ser, ψ Serpentis) is a triple star system within the Serpens Caput part of the equatorial constellation Serpens. Based upon an annual parallax shift of 68.22 mas as seen from Earth, it is located approximately 47.8 light years from the Sun. This system came closest approach to the Sun about 585,000 years ago when it made perihelion passage at an estimated distance of . Psi Serpentis is faintly visible to the naked eye with an apparent visual magnitude of 5.84.
This system can be resolved into two components that orbit each other with a period of 528.79 years and an eccentricity of 0.146. The primary, component A, is a yellow-hued G-type main sequence star with a stellar classification of G5 V. It is a solar analog, but its physical properties differ enough from the Sun to not be considered a solar twin. The star has an estimated 99.3% of the mass of the Sun, and it matches the Sun's radius within the margin of error. It is radiating 98% of the solar luminosity from its photosphere at an effective temperature of 5,683 K.
When observed from 1997 through 2000, the primary component appeared to be transitioning from a maunder minimum state to a state of cycling magnetic activity. It has developed a four-year activity cycle. During the period 2000–2004, it showed a strong activity cycle with little correlation between photometric variation and surface activity. This was followed by a flatter activity cycle from 2004–2008 that showed an inverse brightness variation with the level of activity. The difference in the two cycles may indicate a change from faculae-dominated to star spot-dominated variations in luminosity.
The known secondary, component B, is magnitude 12.00 and lies at an angular separation of 4.6 arc seconds from the primary along a position angle of 18°, as of 2013. In 2015, this component was resolved via interferometry into a binary star system with a separation of 0.22 arc seconds, corresponding to a projected separation of 3 AU. Both components, Ba and Bb, are likely red dwarfs roughly of class M3 with masses of about 25% the mass of the Sun. They have a tentative orbital period of around six years and a semimajor axis of 0.19 arc seconds.


Omicron Centauri

The Bayer designation Omicron Centauri (ο Cen / ο Centauri) is shared by two star systems, in the constellation Centaurus:
They are separated by 0.07° on the sky. They may be physically related.


TW Piscis Austrini

TW Piscis Austrini (also Fomalhaut B) is a dwarf star in the constellation Piscis Austrinus. It lies relatively close to the Sun, at an estimated distance of 24.8 light years.
To an observer on Earth the star is visually separated from its larger companion Fomalhaut A by 2 degrees - the width of four full moons.
The TW in the name is a variable star designation. This is a variable star of the type known as a BY Draconis variable, with surface brightness variations causing the changes as the star rotates. It varies slightly in apparent magnitude, ranging from 6.44 to 6.51 over a 10.3 day period.
TW Piscis Austrini lies within a light year of Fomalhaut A. Due to sharing the same proper motion, and the same estimated age of approximately 440±40 million years, astronomers now consider them to be elements of a multiple star system. A third star, dimmer, and more widely separated, Fomalhaut C, gives the system the widest visual separation, to observers from Earth, at approximately 6 degrees.
In 2019, an exoplanet candidate around Fomalhaut B was detected by astrometry.


55 Pegasi

55 Pegasi is a single star in the northern constellation of Pegasus. It is visible to the naked eye as a faint, reddish-hued point of light with a baseline apparent visual magnitude of 4.51. The star is located approximately 302 light years away from the Sun based on parallax, but it is moving closer with a radial velocity of −5 km/s.
This is an aging red giant star on the asymptotic giant branch with a stellar classification of M1IIIab, having exhausted the supply of hydrogen at its core then expanded to 46 times the Sun's radius. It is a suspected variable, with an observed magnitude that ranges from 4.50 down to 4.56. The star is around two billion years old with 1.6 times the mass of the Sun. It is radiating 483 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,994 K.


Antlia 2

Antlia II (Ant II) is a low-surface-brightness dwarf satellite galaxy of the Milky Way at a galactic latitude of 11.2°. It spans 1.26° in the sky just southeast of Epsilon Antliae. The galaxy is similar in size to the Large Magellanic Cloud, despite being 1/10,000 as bright. Antlia II has the lowest surface brightness of any galaxy discovered and is ~ 100 times more diffuse than any known ultra diffuse galaxy. It was discovered using data from the European Space Agency's Gaia spacecraft in November 2018.


Q Centauri

Q Centauri (Q Cen) is a binary star in the constellation Centaurus. It has a combined apparent magnitude of +4.99 and is approximately 270 light years from Earth.
The primary component, Q Centauri A, is a blue-white B-type main sequence dwarf with an apparent magnitude of +5.7. Its companion, Q Centauri B, is a white A-type main sequence dwarf with an apparent magnitude of +7.1. The two stars are separated by 5.5 arcseconds on the sky.


Rho2 Sagittarii

Rho2 Sagittarii (ρ2 Sagittarii) is a star in the zodiac constellation of Sagittarius. With an apparent visual magnitude of +5.87, it is near the lower limit of stars that can be seen with the naked eye. Based upon an annual parallax shift of 9.82 mas as seen from Earth, it is located around 330 light years from the Sun.
This is an evolved K-type giant star with a stellar classification of K0 III. As a result of a 1997 lunar occultation, a companion star was discovered at an angular separation of 21 mas. It appears to be an A-type main sequence star with a class of around A5. This companion was not detected during prior occultations by the Moon.


Pi Serpentis

Pi Serpentis, Latinized from π Serpentis, is a solitary white-hued star in the constellation Serpens, located in its head, Serpens Caput. Based upon an annual parallax shift of 18.22 mas as seen from Earth, it is located around 179 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.82.
This is an A-type main sequence star with a stellar classification of A3 V. It is about 320 million years old with a high rate of spin, measured at a 128 km/s projected rotational velocity. The star has an estimated 2.50 times the mass of the Sun and 2.27 times the Sun's radius. It is radiating 27 times the solar luminosity from its photosphere at an effective temperature of 7,566 K.
In 1992, an infrared excess was detected from this system at a wavelength of 60μm. The data suggests a dusty debris disk with a temperature of 45 K is orbiting 211 AU from the host star.


Theta Leonis

Theta Leonis, Latinized from θ Leonis, formally named Chertan, is a star in the constellation of Leo. With an apparent visual magnitude of +3.324 it is visible to the naked eye and forms one of the brighter stars in the constellation. The distance from the Sun can be directly determined from parallax measurements, yielding a value of about .
Description.
This is a large star with 2.5 times the mass of the Sun. The spectrum matches a stellar classification of A2 V, making this a seemingly typical A-type main sequence star. However, the spectrum shows enhanced absorption lines of metals, marking this as a chemically peculiar Am star. The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, appears around 12% higher than in the Sun. It is radiating 141 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 9,350 K, literally giving it a white-hot glow.
Theta Leonis is much younger than the Sun, with an estimated age of around 550 million years. It has a moderately high rate of rotation, with a projected rotational velocity of . Measurements in the infrared band show an excess of emission from the star and its surroundings, suggesting the presence of a circumstellar disk of dust. The temperature of this emission indicates the disk has an orbital radius of 36 AU.
Nomenclature.
"θ Leonis" (Latinised to "Theta Leonis") is the star's Bayer designation.
It bore the traditional names "Chertan", "Chort" and "Coxa" . "Chertan" is derived from the Arabic ' 'two small ribs', originally referring to Delta Leonis and Theta Leonis; "Chort" from Arabic ' or ' 'small rib', and ' is Latin for 'hip'. 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 "Chertan" for this star.
In Chinese, (), meaning "Right Wall of Supreme Palace Enclosure", refers to an asterism consisting of Theta Leonis, Beta Virginis, Sigma Leonis, Iota Leonis and Delta Leonis. Consequently, the Chinese name for Theta Leonis itself is (, .), representing (), meaning "The Second Western Minister". 西次相 (Xīcìxiāng), spelled "Tsze Seang" by R.H. Allen, means "the Second Minister of State"


HD 47366

HD 47366 is the "Henry Draper Catalogue" designation for a star in the southern constellation of Canis Major. It has an apparent visual magnitude of 6.12, which puts it near the lower limit of stars visible to the naked eye. According to the Bortle scale, it can be viewed from dark rural skies. Parallax measurements performed by the Gaia spacecraft provide a distance estimate of roughly .
This is a K-type giant star with a stellar classification of K1III: − the colon suffix indicates some uncertainty in the luminosity classification of III. Spectroscopic analysis of the star was used to derive an estimated mass of about 1.81 times the mass of the Sun. It has an estimated age of 1.6 billion years; old enough at that mass to have evolved off the main sequence. As a giant star, the atmosphere has expanded to 7.3 times the Sun's radius, and it is emitting 26 times the solar luminosity at an effective temperature of 4,772 K. The projected rotational velocity of the star is 4.3 km/s, indicating it is rotating with a period of under 86 days.
In 2016, a team of astronomers reported the detection of a pair of giant planetary companions. Radial velocity measurements indicated gravitational perturbations of the star being caused by orbiting objects. The best fit to the preliminary data suggests two periodicities: one almost exactly a year long like the Earth's periodicity, and a second of around two years. Both objects are predicted to have masses greater than that of the planet Jupiter: their minimum masses are 1.8 and 1.9 Jupiter masses, respectively. Until the inclination of their orbits is known, their actual masses cannot be pinned down more accurately.


Abell 36

Abell 36 is a planetary nebula located 780 light years away in the constellation of Virgo.


NGC 7003

NGC 7003 is a spiral galaxy around 220 million light-years from Earth in the constellation Delphinus. NGC 7003 has an estimated diameter of 80,800 light-years. The galaxy was discovered by German astronomer Heinrich Louis d'Arrest on August 26, 1864. There also has been at least one supernova observed in NGC 7003.
SN2011dk.
On May 12, 2011 a Type II supernova designated as SN2011dk was discovered in NGC 7003.


NGC 7790

NGC 7790 is a young open cluster of stars located some 10,800 light years away from Earth in the northern constellation of Cassiopeia. At this distance, the light from the cluster has undergone extinction from interstellar gas and dust equal to E(B – V ) = 0.51 magnitude in the UBV photometric system. NGC 7790 has a Trumpler class rating of II2m and the estimated age is 60–80 million years. It contains three cepheid variables: CEa Cas, CEb Cas, and CF Cas.
This cluster is on an orbit through the Milky Way galaxy that has an eccentricity of 0.22 ± 0.07 and a period of (225.0 ± 27.1) million years. It will come as close as to, and as distant as from, the Galactic Center. The maximum distance reached above (or below) the galactic plane is . On average, it will cross the galactic plane every (35.7 ± 13.0) million years.


Chi Tauri

Chi Tauri (χ Tauri) is a star system in the constellation of Taurus. Parallax measurements made by the "Hipparcos" spacecraft put it at a distance of about 291 light years (89 parsecs) from Earth. The primary component has an apparent magnitude of about 5.4, meaning it is visible with the naked eye.
The main component of the system is Chi Tauri A. It is a B-type main-sequence star. Its mass is 2.6 times that of the Sun and its surface glows with an effective temperature of 10,300 K. It may be a binary star itself, as suggested from astrometric data from Hipparcos, although no orbit could be derived.
The secondary component of the system is Chi Tauri B, separated about 19″ from Chi Tauri A. It was thought to be a post-T Tauri star from its unusual spectrum, but later studies ruled this out. It is a double-lined spectroscopic binary—the two stars are not resolved but their spectra have periodic Doppler shifts indicating orbital motion. The two stars are an F-type star and a G-type star, respectively, and are designated Ba and Bb.
The radial velocity of Chi Tauri B has a slow drift indicating the presence of another star in the system. Designated Chi Tauri Bc, this massive object is too dim to be detected, but it appears in Chi Tauri B's spectrum as an infrared excess. Because of this infrared excess, this unseen component is thought to be a pair of K-type main-sequence stars both with masses 70% of the Sun. The stars within the system appear to be dynamically interacting.


NGC 3545B

NGC 3545B is an elliptical galaxy in the constellation Ursa Major. The object is close to NGC 3545.


Mu Pictoris

μ Pictoris, Latinised as Mu Pictoris, is a binary star system in the southern constellation Pictor. It is bright enough to be dimly visible to the naked eye, having a combined apparent visual magnitude of 5.69. Based upon an annual parallax shift of 4.31 mas as seen from Earth, the system is located roughly 760 light years distant from the Sun. As of 2010, the pair have an angular separation of 2.46 arc seconds along a position angle of 221°.
The primary, designated component A, is a blue-white star with a visual magnitude of 5.71 and a stellar classification of B9 Ve or B9 IVn. The first classification suggests is a B-type main-sequence star, with the 'e' suffix indicating a Be star. The second may instead indicate a somewhat more evolved B-type star that is spinning rapidly, resulting in "nebulous" absorption lines. Photometrically, it shows a pulsation period of 0.397 days, which is likely the same as the rotation period.
The secondary companion, component B, is a white-hued star of magnitude 9.43 with a classification of A8 V:p?. This indicates it is an A-type main-sequence star, with the 'p?' suffix suggesting it may be chemically peculiar while the ':' notation says there is some uncertainty about the general classification.


68 Cygni

68 Cygni is the Flamsteed designation for a star in the constellation Cygnus. Located approximately distant, the star is a hot blue giant of spectral type O7.5IIIn((f)), a massive star that is likely currently expanding to become a supergiant. The star is surrounded by a ring-shaped nebula (likely a Strömgren sphere) named S 119.
68 Cygni is currently classified as a rotating ellipsoidal variable, varying between apparent magnitudes 4.98 and 5.09, although the classification as a rotating ellipsoidal variable is subject to controversy. Barely visible to the naked eye, the star is likely to have a mass of around 26 solar masses and a temperature of approximately 34,000 kelvins, although many of the star's physical parameters are subject to uncertainties due to the unclear nature of the system.
Naming.
Being visible to the naked eye, 68 Cygni would have been observable since ancient times, but the first known cataloging and designation of the star was by Johann Bayer, who assigned it the Bayer designation A Cygni. Bayer grouped stars into six magnitude groupings (1st- through 6th-magnitude) and assigned Greek letters to the brightest 24 stars in these groupings, sorted by right ascension within groups. When he ran out of Greek letters, Bayer then moved on to Latin letters; thus, 68 Cygni was the 25th star Bayer designated in Cygnus.
The star was later observed by John Flamsteed, who cataloged naked-eye stars by constellation. Contrary to popular belief, Flamsteed did not assign the stars Flamsteed designations; rather, the French astronomer Joseph Jérôme de Lalande assigned Flamsteed numbers to stars in each constellation in order of right ascension. Since this star was the 68th star by right ascention in Cygnus, it was numbered 68 Cygni, the designation by which this star is most commonly known today, as most Latin-letter Bayer designations are no longer in common use.
After the star was discovered to be variable, it was assigned a variable star designation. As the 1809th variable star without a Bayer designation to be discovered in Cygnus, 68 Cygni was assigned the designation "V1809 Cygni" in 1984.
Observation.
68 Cygni has an apparent magnitude of approximately 5.0, making the star a fairly inconspicuous star in the night sky, and nearly invisible when the moon is full. With a new moon, according to the Bortle scale, the star cannot be easily seen with the naked eye from polluted areas or with a full moon, but can be seen from suburban areas when overhead.
In the night sky, 68 Cygni is located west of the main asterism of Cygnus, approximately seven degrees east-southeast of the first-magnitude star Deneb. This is near the midpoint of the imaginary line between the 3rd-magnitude stars Xi Cygni and Rho Cygni. The star can also be found by continuing north along the line between the stars Zeta Cygni, Upsilon Cygni, Tau Cygni, and Sigma Cygni, as 68 Cygni is the first easily visible naked-eye star one will come to.
Properties.
According to the star's measured parallax of 0.70 milliarcseconds, it is located approximately distant, although such low parallax values are subject to low precision. With taking into account the error estimate of 0.23 milliarcseconds, the star's distance could be anywhere between and distant, although values close to the mean value are more likely.
68 Cygni is a massive blue giant of spectral type O7.5IIIn((f)). Such massive stars only remain in the main sequence phase for a few million years, less than a thousandth of the expected main sequence lifetime of the sun. 68 Cygni has already expanded off the main sequence to become a blue giant, and is likely expanding to become a blue supergiant, although for very hot stars such as 68 Cygni evolution to the giant and supergiant classes does not indicate exhaustion of core hydrogen, nor is it accompanied by a large increase in luminosity. Instead the products of fusion burning are distributed throughout the star by convection and rotational mixing, producing helium and nitrogen lines in the spectrum, leading to an increase in the thickness of the stellar wind, and accompanied by a modest expansion and cooling of the star. The "n" in the spectral type indicates the presence of broad absorption lines due to how rapidly the star is spinning. The "((f))" indicates strong absorption in the He II spectral lines and weak N III emission lines.
The star is currently tentatively classified as a rotating ellipsoidal variable, varying between magnitudes 4.98 and 5.09. Rotating ellipsoidal variables are binary systems in which the constituent components are distorted into ellipses due to fast rotation rates, and as the two stars orbit each other, the surface area of the star facing Earth changes, causing variations in brightness. However, the actual cause of the variability, and even whether or not there is a companion, is uncertain. No companion has ever been directly detected, but its existence has been inferred from spectral line variations in the primary O-type star. A period of 5.1 days has been assigned for the orbit of the binary, which is approximately the same as the rotation period of the star. Unlike typical rotating ellipsoidal variables, there is no clearly defined period in the variations in brightness. Data derived from the assumption of a binary system, for example the mass, are highly uncertain due to the lack of information about the inclination or eccentricity of the orbit, or even whether there is a companion.
The spectral lines of 68 Cygni vary erratically, but possibly with a period around 5 days. The lines frequently show P Cygni profiles with both an absorption and emission component slightly offset due to doppler shifting. The emission component arises primarily in the stellar wind and the absorption component in the photosphere. The emission components of the spectral lines are largely constant, but the absorption components vary, leading to changes in the line profiles. This is strongest in the ultraviolet part of the electromagnetic spectrum and has been extensively studied by the International Ultraviolet Explorer satellite. The type and scale of the spectroscopic variations indicates large-scale structures within the stellar wind.
68 Cygni is known to be surrounded by a ring-shaped nebula, named S 119. Although it was originally proposed that this nebula was formed from 68 Cygni's stellar wind, it now appears that the nebula is simply a Strömgren sphere that is being ionized by 68 Cygni. Instead, the stellar wind is likely, due to the star's high velocity through space, forming a bow shock.
The mass of the star is likely to be around 26 solar masses, according to a 2011 study by Ducati, Penteado, and Turcati. However, due to the uncertain nature of the binary system hypothesis, the true mass could be much different than this. If the star actually has a mass of 51 solar masses (the median mass reported by Hohle, Neuhäuser, and Schutz in 2010), the star's bolometric luminosity would be over 1 million solar luminosities, making it among the most luminous stars known, although data to support this mass is tenuous at best.


34 Pegasi

34 Pegasi is a triple star system in the northern constellation of Pegasus. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.76. The system is located at a distance of 131 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −13.5 km/s. It has been catalogued as a member of the Hyades Supercluster, although its membership status remains doubtful.
The innermost system is a single-lined spectroscopic binary with an orbital period of and an eccentricity of 0.44. The orbital plane of this pair is being viewed nearly edge-on, and has an angular semimajor axis of . A third member of the system has a poorly-constrained 420 year orbit around the main pair. This star was discovered by Burnham in 1874, and the discovery code BU 290 was given to the double. As of 2015, it lies at an angular separation of along a position angle of from the inner system.
The primary member, component Aa, is an F-type main-sequence star that is starting to evolve off the main sequence, with stellar classifications of F7V or F8IV−V, depending on the source. It is around three billion years old and is spinning with a projected rotational velocity of 8 km/s, with a measured rotation period of 12 days. The star has 1.3 times the mass of the Sun and 2.25 times the Sun's radius. It is radiating 6.7 times the luminosity of the Sun from its photosphere at an effective temperature of 6,200 K.
The secondary companion to the primary, component Ab, is most likely a red dwarf star with around 29% of the mass of the Sun. The tertiary member, component B, has 53% of the Sun's mass and a class of around K4.


List of stars in Sagittarius

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


36 Comae Berenices

36 Comae Berenices is a single star in the northern constellation of Coma Berenices. It is faintly visible to the naked eye with an apparent visual magnitude of 4.76. The distance to this star, as determined from an annual parallax shift of , is 349 light years. It is moving closer to the Earth with a heliocentric radial velocity of −1.5 km/s.
This is an evolved red giant star with a stellar classification of M0.5 III, currently on the asymptotic giant branch of the Hertzsprung–Russell diagram. This indicates it has consumed the hydrogen at its center and is now generating energy through hydrogen and helium fusion along shells surrounding an inert carbon and oxygen core. It has expanded to 43 times the radius of the Sun and is radiating 372 times the Sun's luminosity from its photosphere at an effective temperature of 3,890 K.


Alpha Crateris

Alpha Crateris (α Crateris, abbreviated Alpha Crt, α Crt), officially named Alkes , is a star in the constellation of Crater. It is a cool giant star about away.
Nomenclature.
"α Crateris" (Latinised to "Alpha Crateris") is the star's Bayer designation.
It bore the traditional name "Alkes", from the Arabic الكاس "alkās" or الكأس "alka's" "the cup". In the catalogue of stars in the "Calendarium" of Al Achsasi al Mouakket, this star was designated "Aoul al Batjna" (أول ألباطیة "awwal al-bāṭiya"), which was translated into Latin as "Prima Crateris", meaning "first [star] of the Cup". 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 "Alkes" for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Wings (asterism)", refers to an asterism consisting of Alpha Crateris, Gamma Crateris, Zeta Crateris, Lambda Crateris, Nu Hydrae, Eta Crateris, Delta Crateris, Iota Crateris, Kappa Crateris, Epsilon Crateris, HD 95808, HD 93833, Theta Crateris, HD 102574, HD 100219, Beta Crateris, HD 99922, HD 100307, HD 96819, Chi1 Hydrae, HD 102620 and HD 103462. Consequently, Alpha Crateris itself is known as (, ).
Namesake.
 was a United States Navy named after the star.
Properties.
Alpha Crateris is an orange giant of spectral type K1III. It has an apparent magnitude of 4.07, and is 174 light-years from Earth. It is thought to be a horizontal branch star, meaning it is fusing helium in its core after a helium flash. Cool horizontal branch stars are often called red clump giants as they form a noticeable grouping near the hot edge of the red giant branch in the H–R diagrams of clusters with near-solar metallicity. On this basis it is calculated to have a mass of , a luminosity of , and an age around two billion years. Its surface temperature is 4645 K. Or it might be a red-giant branch star, still fusing hydrogen in a shell around an insert helium core, in which case it would be slightly less massive, older, cooler, larger, and more luminous.


30 Leonis Minoris

30 Leonis Minoris is a single star in the northern constellation of Leo Minor. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.72. The distance to this star, as estimated from parallax measurements, is 233 light years. It is drifting away from the Earth with a heliocentric radial velocity of +13.7 km/s.
This object has been catalogued as an Am star and was given a stellar classification of kF0hF2mF2 by Abt and Morrell (1995). This notation indicates the calcium K line matches an F0 star, while the hydrogen and metal lines fit an F2 star. However, Gray et al. (2001) assigned it a class of A9IIIa, matching an A-type giant star.
30 Leonis Minoris has 2.3 times the mass of the Sun and 4.2 times the Sun's radius. It has a moderate rate of spin, showing a projected rotational velocity of 34 km/s. The star is radiating 58 times the Sun's luminosity from its photosphere at an effective temperature of 7,292 K.


Beta Corvi

Beta Corvi (β Corvi, abbreviated Beta Crv, β Crv), officially named Kraz , is the second-brightest star in the southern constellation of Corvus with an apparent visual magnitude of 2.647. Based on parallax measurements obtained during the Hipparcos mission, it is about distant from the Sun.
Nomenclature.
"β Corvi" (Latinised to "Beta Corvi") is the star's Bayer designation.
In a 1951 publication, "Atlas Coeli" (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář, it bore the name "Kraz", whose origin and meaning remain unknown. 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 "Kraz" for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Chariot (asterism)", refers to an asterism consisting of Beta, Gamma, Epsilon and Delta Corvi. Consequently, Beta Corvi itself is known as (, ).
Properties.
Beta Corvi has about 3.7 times the Sun's mass and is roughly 206 million years old, which is old enough for a star of this mass to consume the hydrogen at its core and evolve away from the main sequence. The stellar classification is G5 II, with the luminosity class of 'II' indicating this is a bright giant. The effective temperature of the star's outer envelope is about 5,100 K, which produces a yellow hue common to G-type stars.
The measured angular diameter of this star is . At an estimated distance of , this yields a physical size of about 16 times the radius of the Sun. Because of the star's mass and radius, it is emitting about 164 times the luminosity of the Sun. The abundance of elements other than hydrogen or helium, what astronomers term metallicity, is similar to the proportions in the Sun.
This is a variable star that ranges in apparent visual magnitude from a low of 2.66 to a high of 2.60.
References.
\end{align}</math></ref>


HD 63922

HD 63922 is a class B0III (blue giant) star in the constellation Puppis. Its apparent magnitude is 4.11 and it is approximately 1600 light years away based on parallax.
It is a multiple star; the primary has one close companion, Ab, at 0.3" separation and magnitude 7.19, and a more distant one, B, at 59.1" and 8.79 magnitude.


77 Ceti

77 Ceti is a single, orange-hued star located 489 light years away in the equatorial constellation of Cetus. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.7. This is an evolved giant star with a stellar classification of K2 III. It is radiating 187 times the Sun's luminosity from its photosphere at an effective temperature of 4,206 K.


Cygnus OB9

Cygnus OB9 is an OB association in Cygnus. It is near to the Cygnus OB2 association. The region is embedded within a wider one of star formation known as Cygnus X, which is one of the most luminous objects in the sky at radio wavelengths. The region is approximately 5000 light years from Earth in the constellation of Cygnus.
Although Cygnus OB9 has many O and B type stars, Cygnus OB9 is also hidden behind a massive dust cloud known as the Cygnus Rift like Cygnus OB2.


Phi Ophiuchi

Phi Ophiuchi, a name Latinized from φ Ophiuchi, is a single star in the equatorial constellation of Ophiuchus. It has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.27. The star is located at a distance of approximately 244 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −33.5 km/s.
The stellar classification of Phi Opiuchi is G8+IIIa, an evolved giant star that has exhausted the supply of hydrogen at its core. In 2000, D. R. Alves identified it as a red clump giant on the horizontal branch that is generating energy by core helium fusion. However, S. Reffert and associates in 2015 instead placed it on the red giant branch. A 2018 study by S. Stock and associates used Bayesian estimates to arrive at a 94% chance the star is on the horizontal branch.
The star is around 360 million years old with an estimated 3.16 times the mass of the Sun and 13.4 times the Sun's radius. It is radiating 112 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,131 K.
It has two visual companions, component B, at magnitude 12.9 and separation 41.3", and component C, at magnitude 10.8 and separation 119.8".


HD 83446

HD 83446 is a probable astrometric binary star system in the constellation Vela. It is visible to the naked eye with an apparent visual magnitude of 4.34. Based upon an annual parallax shift of , it is located 107.1 light years from the Sun. The system is moving further away with a heliocentric radial velocity of +18 km/s.
The visible component is an A-type main-sequence star with a stellar classification of A7 V. Observations with the BRITE constellation led to this star's identification as a Delta Scuti variable with pulsation periods of 31.0806 and 34.2098 days. It has a high rate of spin with a projected rotational velocity of 155 km/s, which is giving the star an oblate shape with an equatorial bulge that is 6% larger than the polar radius. The star is roughly 453 million years old with 1.8 times the mass of the Sun. It is radiating 16 times the Sun's luminosity from its photosphere at an effective temperature of 8,331 K.


55 Ursae Majoris

55 Ursae Majoris (55 UMa) is a triple star system in the constellation Ursa Major. Its apparent magnitude is 4.80. Two stars form a close spectroscopic binary with an orbital period of 2.55 days. The third star orbits the central pair every 1873 days. All three stars are A-type main-sequence stars.


84 Ceti

84 Ceti is the Flamsteed designation for a binary star system in the equatorial constellation of Cetus. It has an apparent visual magnitude of 5.7, making it faintly visible to the naked eye from dark suburban skies. Parallax measurements with the Hipparcos spacecraft put this system at a distance of around 74 light years.
The primary, 84 Ceti A, is an F-type main sequence star with a stellar classification of F7V. It is slightly larger than the Sun, with 117% of the Sun's mass, 121% of the radius, and 213% of the luminosity. The abundance of elements more massive than helium is 71% of the Sun's and it has a relatively high projected rotational velocity of 32 km/s. This star is estimated to be less than half the age of the Sun, at 2.1 billion years.
The secondary component, 84 Ceti B, has a classification of K2V, making it a K-type main sequence star. It lies at an angular separation of 3.3″ from the primary, which is equivalent to a physical separation of at least 74.5 AU.
The space velocity components of this system are: –13(U), –25(V), –2(W) km/s. Based upon the position and motion, it is a candidate member of the Tucana-Horologium Association; this is a group of stars that share a similar motion through space and hence may have originated in the same molecular cloud. 84 Ceti is following an orbit through the Milky Way galaxy that has an eccentricity of 0.03, taking it as close as and as far as from the Galactic Center. The inclination of the orbital plane carries it as far as away from the galactic plane.


52 Cygni

52 Cygni is a giant star in the northern constellation of Cygnus with an apparent magnitude of 4.22. Based on its Hipparcos parallax, it is about away.
52 Cygni is a probable horizontal branch (red clump) star, fusing helium in its core, although there is a 25% chance that it is still on the red giant branch (RGB) and fusing hydrogen in a shell around an insert core. As a clump giant it would be 2.27 gyr old, but only 910 myr if it is an RGB star. It shines with a bolometric luminosity of about at an effective temperature of 4,677 K. It has a radius of .
At an angular separation of 6.0″ from 52 Cygni is a faint magnitude 9.5 companion.


T Ursae Minoris

T Ursae Minoris (T UMi) is a star in the constellation Ursa Minor, located 2'30" west-southwest of 3 Ursae Minoris toward the western border of the constellation with Draco.
Properties.
A red giant ranging between spectral types M4e and M6e and with a surface temperature of 3300 K, it is a long period Mira variable ranging from magnitude 7.8 to 15. These are highly evolved ageing stars that are on the asymptotic giant branch, their wide range in magnitude making them ideal targets for monitoring by amateur star observers.
T Ursae Minoris has been monitored closely since 1905. Up until 1979, its brightness had varied over a period of 310 to 315 days. However, from 1979 its period decreased suddenly to 274 days, and appeared to be decreasing by 2.75 days a cycle since. Variable star observers Janet Mattei and Grant Foster proposed that the star had just undergone a shell helium flash – a point at which "the helium shell around the dense core of the star reaches a critical mass and ignites", which "influences the star's pulsation via changes in surface luminosity and radius". By mid 2008, its period had decreased to 230 days (thus removing it by definition from the class of Mira variables), before changing to pulsation as a semiregular variable star, with a dominant period of 113.6 days. This has been the most dramatic change of any Mira variable. The lack of technetium in its spectrum indicates it is not as advanced in age as some other Mira-type stars, as it has either not yet dredged up this sort of material from its core or is of insufficient mass for this to occur.


Stephenson 2

Stephenson 2 (also known as RSGC2) is a young massive open cluster belonging to the Milky Way galaxy. It was discovered in 1990 in the data obtained by a deep infrared survey. The cluster is located in the constellation Scutum at the distance of about 6 kpc from the Sun. It is likely situated at the intersection of the northern end of the Long Bar of the Milky Way and the inner portion of the Scutum–Centaurus Arm—one of the two major spiral arms.
26 red supergiants have been confirmed as members of the cluster, far more than any other known cluster, both in and out of the Milky Way. This includes Stephenson 2-18, which is one of the largest stars currently known. A more recent study has identified around 80 red supergiants in the line of sight of Stephenson 2, approximately 40 of them with radial velocities consistent with being cluster members. However these stars are spread over a wider area than a typical cluster, indicating an extended stellar association similar to that found around the nearby cluster RSGC3.
The age of Stephenson 2 is estimated at 14–20 million years. The observed red supergiants with the mass of about 12–16 solar masses are type II supernova progenitors. The cluster is heavily obscured and has not been detected in the visible light. It lies close to other groupings of red supergiants known as RSGC1, RSGC3, Alicante 7, Alicante 8, and Alicante 10. The mass of the open cluster is estimated at 30–50 thousand solar masses, which makes it the second most massive open cluster in the Galaxy.


NGC 3596

NGC 3596 is an intermediate spiral galaxy in the constellation Leo. It was discovered by William Herschel 1784. It is located below the star Theta Leonis (Chertan).


SV Centauri

SV Centauri is a variable star in the constellation Centaurus. An eclipsing binary, its visual apparent magnitude has a maximum of 8.71, fading to 9.98 during primary eclipse and 9.42 during secondary eclipse. From its brightness, it's estimated to be around 6,000 light-years (1,800 parsecs) away from Earth. Parallax measurements from Gaia Data Release 2 yield a similar distance of around .
SV Centauri is a contact binary made of two hot B-type stars with spectral types of B1V and B6.5III and effective temperatures of 23,000 and 14,000 K. The primary component, the brighter star with 11,700 times the solar luminosity, is the less massive one with 7.7 times the solar mass and has a radius of 6.8 times the solar radius. The secondary component has a mass equal to 9.6 solar masses, radius of 7.4 solar radii and a brightness 1,900 times larger than the Sun's. The separation between the center of each star is only 15.3 solar radii. The system is viewed from a high inclination of 81.8°.
The orbital period of SV Centauri is monotonically decreasing at a very fast mean rate of 2.1 seconds per year, the largest rate for any known system. The first observations of the system, in 1894, revealed a period of 1.6606 days, which decreased to 1.6581 days in 1993, showing a decrease rate that is variable with time, but with time intervals of 10-30 years when it is constant. The transition between such intervals of constant change can be accompanied by very fast decreases in the period, such as of 15 seconds per year in 1975.
The most probable explanation for the period decrease is mass transfer from the less massive to the more massive star and subsequent mass loss through the L3 Lagrangian point of the system, which is located on the outer side of the more massive star. The mass loss causes loss of angular momentum, which is compensated by a decrease in the separation between the stars. In this model, the system is losing mass at a rate of about 5 solar masses per year; the variation of this rate causes the variation in the rate of period decrease. The alternative possibility is mass transfer from the more massive to the less massive star, which naturally tends to decrease the orbital period. This may create an accretion disk around the less massive star, similar to Beta Lyrae.


23 Comae Berenices

23 Comae Berenices is a binary star system in the northern constellation of Coma Berenices, situated a few degrees away from the North Galactic Pole. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.80. The system is located around 310 light years away from the Sun, based on parallax. It is moving closer to the Earth with a heliocentric radial velocity of −16 km/s.
The components of this system orbit each other with a period of 33 years, a large eccentricity of 0.9, and an angular semimajor axis of . The primary, designated component A, is a magnitude 4.96 star with a stellar classification of A0IV, matching an A-type subgiant that has exhausted the supply of hydrogen at its core and is in the process of evolving into a giant. Bychkov et al. (2009) list it as an Am star with an average field strength of .
The primary is 210 million years old and is spinning with a projected rotational velocity of 40 km/s. It has 2.15 times the mass of the Sun and about three times the Sun's radius. The star is radiating 104 times the luminosity of the Sun from its photosphere at an effective temperature of 9,675 K.


RS Puppis

RS Puppis (or RS Pup) is a Cepheid variable star around away in the constellation of Puppis. It is one of the biggest and brightest known Cepheids in the Milky Way galaxy and has one of the longest periods for this class of star at 41.5 days.
Distance.
The distance to RS Puppis is important because Cepheids serve as a marker for distances within the Milky Way galaxy and for nearby galaxies.
Because it is located in a large nebula, astronomers using the ESO's New Technology Telescope at La Silla Observatory, Chile have been able to measure its distance in 2008 by strictly geometric analysis of light echoes from particles in the nebula, determining it to be from Earth, the most accurate measurement achieved for any Cepheid as of early 2008.
The light echo technique was used again in 2014, this time with Hubble Space Telescope Advanced Camera for Surveys polarimetric images. The distance obtained by these measurements is .
In Gaia Data Release 2, a direct geometric parallax of was derived, corresponding to a distance of .
Variability.
RS Puppis is a classical Cepheid variable and its brightness changes regularly due to pulsations during which its size and temperature both vary. Its visual magnitude changes from 6.52 at maximum to 7.67 at minimum. The light curve shows a rapid rise in brightness with the slower drop in brightness taking about three times as long. It has a regular period of 41.5 days but it changes very slowly and erratically. For example, the period has changed on average by about 144.7 s per year, but has sometimes remained constant for several years.
RS Puppis is considered to be a long-period Cepheid because it has a period longer than 10 days. The only nearer long-period Cepheid is l Carinae. Cepheids closely follow a period-luminosity relationship, with more luminous stars having longer periods. RS Puppis has one of the longest periods of Cepheids in the Milky Way and therefore is also one of the most luminous.
Properties.
RS Puppis is a supergiant with a spectral classification of G2Ib, although its spectral type varies between F9 and G7 as its temperature changes. It lies on the instability strip and based on the rate of change of its period is thought to be crossing it for the third time. The third crossing occurs as a star is evolving towards cooler temperatures for the second time after performing a blue loop. The third crossing of the instability strip occurs much more slowly than the first crossing just after a star leaves the main sequence.
RS Puppis pulsates every 41.5 days, during which time its radius, temperature, and luminosity change. Typically for long-period Cepheids, it pulsates in the fundamental mode. The radius varies between and , although the changes vary somewhat even from one cycle to the next. The temperature varies between a minimum of and , and the bolometric luminosity between and .


Epsilon Crateris

Epsilon Crateris (ε Crateris) is a solitary star in the southern constellation of Crater. Visible to the naked eye, it has an apparent visual magnitude of 4.84. It is located in the sky above Beta Crateris, and slightly to the left, or east, marking the lower right edge of the rim of the bowl and is somewhat closer to Theta Crateris, which is further east at the top of the bowl. With an annual parallax shift of 8.67 mas as seen from the Earth, its estimated distance is around 376 light years from the Sun.
This is an evolved K-type giant star with a stellar classification of K5 III. It has about the same mass as the Sun, but has expanded to 44.7 times the Sun's radius. The star is radiating 391 times the solar luminosity from its outer atmosphere at an effective temperature of 3,930 K.


Gamma Coronae Australis

Gamma Coronae Australis (γ CrA), is a binary star located in the constellation Corona Australis. The system has a combined apparent visual magnitude of 4.20, making it faintly visible to the naked eye. It is located 56.4 light-years (17.3 parsecs) from the Sun, based on its parallax. Gamma Coronae Australis is a member of the Milky Way's thin disk.
The system is a visual binary, where the orbit is calculated from observations of one star orbiting the other. The primary, Gamma Coronae Australis A, is a late F-type main-sequence star with an effective temperature of 6,090 K. It has an absolute an absolute magnitude of +3.73, and a mass of 1.15 solar masses. The secondary, Gamma Coronae Australis B, is also F-type. With an effective temperature of 6,100 K, an absolute magnitude of +3.80, and a mass of 1.14 solar masses, the companion is almost identical to the primary. Gamma Coronae Australis has been known to be a binary for a long time, and its two components have been given Henry Draper Catalogue designations of HD 177474 and HD 177475, respectively. The two stars are separated by 1.896″ and orbit each other every 121.76 years.


Mu Horologii

Mu Horologii (μ Horologii) is a solitary, yellow-white hued star in the southern constellation of Horologium. It is faintly visible to the naked eye with an apparent visual magnitude of 5.11. Based upon an annual parallax shift of 23.04 mas as seen from Earth, it is located about 141.6 light years from the Sun.
This is an evolving F-type star with a stellar classification of F0 III/IV, showing mixed traits of a subgiant and a giant star. It is around two billion years old with a projected rotational velocity of 79.2 km/s. The star has 1.5 times the mass of the Sun and is radiating 13 times the solar luminosity from its photosphere at an effective temperature of 6,898 K.


Rho Geminorum

Rho Geminorum (ρ Gem) is a star system that lies approximately 59 light-years away in the constellation of Gemini, about 5 arcminutes east of Castor. The system consists of a primary bright enough to be seen with the naked eye, a faint secondary which has rarely been observed even professionally, and a distant, somewhat bright tertiary which requires telescopic equipment for observation.
Components.
Rho Geminorum A is a bright star with a spectral type F0V, meaning that it is a main sequence that is over a thousand kelvins hotter, one-third more massive, two-thirds larger and five-and-a-half times more luminous than the Sun. With an apparent magnitude of 4.25, it is approximately the seventeenth-brightest star in the constellation of Gemini. Though there are some sources indicating that the star is a spectroscopic binary, including the Washington Double Star Catalog (WDS) and the Gliese Catalogue of Nearby Stars, no orbit has been provided.
The WDS lists four companions to Rho Geminorum. Of these, surprisingly little is known about the closest companion, the magnitude 12.5 Rho Geminorum B. The most recent measurement lists a separation of 3.4 arcseconds, corresponding to a separation perpendicular to the line of sight of approximately 85 AU. The spectral type listed in SIMBAD is M5, though this is without a source; Plotting the star's absolute magnitude on the Hertzsprung-Russell diagram (see left) indicates a B-V of 1.53, a value closer to that of an M3V star. Peculiarly, the five observations recorded in the WDS date between 1910 and 1935 and none have been made since; even in literature, more recent attempts to resolve Rho Geminorum B have been unsuccessful. The measurements listed in the WDS seem to be inconsistent with the star being in the background, so the reasons for the failure to observe Rho Geminorum B is unclear.
The next-closest companion, the magnitude 11.59 WDS 07291+3147 C, had a much larger separation of 211.6 arcseconds in 1886. However, this separation increased by 10 arcseconds by 2001, indicating that it is a background star that is unrelated to Rho Geminorum. Correcting for Rho Geminorum A's proper motion, this star's proper motion is RA = -19 mas/yr and Dec = -55 mas/yr. This is a modestly large value, consistent with a distance of a few hundred light-years. WDS 07291+3147 C is itself listed as having a companion, the magnitude 13.20 WDS 07291+3147 D. Relative to WDS 07291+3147 C its separation has remained at about 100 arcseconds between 1909 and 2001, indicating similar proper motion. While this would indicate that the two stars are bound, at a large distance this separation would indicate a separation of at least several thousand AU and their mutual separation has not been entirely consistent (the position angle has increased from 267 to 270°, and the separation has decreased from 104.1 to 102.3 arcseconds). It is therefore possible that the two background stars are bound, but it is not certain.
The final companion in the WDS, the magnitude 7.86 WDS 07291+3147 E (Rho Geminorum C), has a larger still separation of 756 arcseconds, translating to a separation perpendicular to the line of sight of about 18600 AU. The position of this star relative to the primary has remained consistent over decades, indicating that it has a common proper motion and is therefore a wide tertiary component. The wide separation has also facilitated for observations without contamination from Rho Geminorum A, and as of such Rho Geminorum C has its own Gliese catalogue number (273.1) and Hipparcos catalogue number (36357). The Hipparcos parallax is consistent with that of the primary to 1σ, leading to a probability that they are bound of approximately 100%. The star is also known to be a BY Draconis variable with a period of 11.63 days, caused by varying brightness as starspots move across the stellar surface across its rotation period. While the derived age for Rho Geminorum A of 2.1 billion years is not excessively young, Rho Geminorum C is still very active: It has an S'HK of about 0.5, a value similar to that of the near-analogous Epsilon Eridani whose Log R'HK is -4.45. This is much higher than a "quiet" value of <-4.8, making Rho Geminorum C bizarrely active for a modestly old star.
The Rho Geminorum system is an interesting look into a system architecture similar to the 40 Eridani system while the most massive component is on the main sequence, before becoming a white dwarf.


AB Andromedae

AB Andromedae (AB And) is a binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 9.49 but shows a variation in brightness down to a magnitude of 10.46 in a periodic cycle of roughly 8 hours. The observed variability is typical of W Ursae Majoris variable stars, so the two stars in this system form a contact binary.
System.
The observed spectral type of both stars in this system is G5, and one of them is a main sequence star very similar to the sun. They are orbiting so close that their envelopes touch each other. This is a dynamically stable phase that should last until one of the two stars leaves the main sequence.
The system could also host a third body with an orbital period of 19,046 days, with a minimum mass of 0.007 and an eccentricity of 0.22, but not all data collected in time are consistent with this hypothesis.
Variability.
The two stars eclipse each other during their orbit, but they have an elongated shape so they show a constant variation instead of discrete eclipses. Anyway, a periodicity can be seen clearly, but it changes with time; the period shows a long-term trend and a periodic modulation of 7,000 days. The effects responsible for this behaviour could be a third body in the system, magnetic interaction between two stars, mass transfer from one star to the other, mass loss of the system, and recently even an internal mechanism in the touching envelopes have been proposed.


Mercer 3

Mercer 3 is a heavily obscured globular cluster embedded in the disk of the Milky Way galaxy. It was discovered in 2008 in the data obtained by 2MASS and GLIMPSE infrared surveys. The cluster is located in the Scutum constellation. It had avoided detection for such a long time due to the extremely strong foreground extinction in its direction reaching 24 magnitudes in the visible light. Mercer 3 is probably situated at the distance from 4 to 8 kpc from the Sun and has a half-light radius of 0.7–1.5 pc.
Mercer 3 is an old globular cluster having the age of about 12 billion years. The mass of cluster is estimated at 2–3 hundred thousand solar masses.


NGC 5962

NGC 5962 is a spiral galaxy in the constellation Serpens Caput and is the brightest member of the Serpens galaxy cluster. Along with a populated nucleus, it has a relatively large core, but a small central bulge, in which spiral arms begin to unfurl. It appears to have three smaller, orange-hued, dwarf galaxy satellites.
About six solar masses of material form into stars every year in NGC 5962. It is an 11.3 magnitude object that appears 2.5' × 1.5' in the night sky at 90 million light years away, but is still associated with the Virgo supercluster. It has a right ascension of 15h 36.5m and a declination of 16°36'.
Discovery.
NGC 5962 was discovered by British astronomer Sir. William Herschel in 1784 using his Newtonian reflector, the largest telescope in the world at that time.
Observations.
It has been measured by the GALEX spacecraft that NGC 5962 has a redshift of 1957 ± 2 km/s.
Physical characteristics.
The exact size or mass of the galaxy is not known, but there have been estimates of its mass using the velocities of its companion galaxies. The number of stars estimated within NGC 5962 reaches (1 ± 2.5) × 10 to the 12th power stars.


NGC 390

NGC 390 is a star located in the constellation Pisces. It was discovered on November 19, 1884 by Guillaume Bigourdan. It was described by Dreyer as very faint, very small, stellar." However, this position precesses to a position where there is nothing apart from a few scattered stars. However, Bigourdan's original measurements point exactly to a star, which is the most likely candidate for NGC 390; however, as a result of this confusion, a galaxy nearby (PGC 4021) has sometimes been mistaken as NGC 390.


NGC 5930

NGC 5930 is a starburst galaxy in the constellation Boötes that is interacting with the nearby Seyfert galaxy NGC 5929. 5930 has a morphological classification of SAB(rs)b pec, indicating that it is a weakly-barred spiral galaxy with a poorly defined nuclear ring structure. It is inclined at an angle of 46° to the line of sight from the Earth.


List of stars in Lyra

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


Lambda Octantis

λ Octantis, Latinized as Lambda Octantis, is a binary star system in the southern circumpolar constellation of Octans. It is visible to the naked eye as a dim point of light with a combined apparent visual magnitude of 5.27. The distance to this system is approximately 398–409 light years, based on parallax, but it is moving closer with a radial velocity of −10 km/s.
The primary, designated component A, is an aging, yellow-hued star with a stellar classification of class G8-K0III and a visual magnitude of 5.64. Having exhausted the supply of hydrogen at its core, it has expanded and cooled off the main sequence, becoming a giant. At present it is about 200 million years old and has 13 times the girth of the Sun. This star is radiating 102 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,048 K.
The magnitude 7.25 secondary companion, component B, is an Am star with a class of kA3hA7VmA8. This notation indicates it has the calcium K line of an A3 class star, the hydrogen lines of a cooler A7 main sequence star, and the metal lines of an A8 star. As of 2008, it lies at an angular separation of from the primary.


Lynx Arc

The Lynx Arc was discovered in 2003 and is considered to be the hottest known star-birthing region in the Universe as of October 2003. It is located at .
It is located in the constellation Lynx, 12 billion light years away (z=3.357) from Earth, 8 million times farther away and one million times brighter than the Orion Nebula. It contains about 1 million blue stars, while the Orion Nebula only contains 4.
The Lynx Arc was found in a systematic search around galaxy cluster RX J0848+4456 (z=0.570), with the help of a gravitational lens, a 4.5 billion light years distant galaxy cluster (CL J0848.8+4455 lying at z=0.543). Amongst others the Keck Observatory, the Hubble Space Telescope and ROSAT participated in the search.
Located behind a cluster of galaxies in northern Constellation Lynx around 12 billion light-years (ly) away, the Lynx Arc is a distant supercluster of extremely hot, young stars. Roughly one million times brighter than the well-known Orion Nebula, the Lynx Arc contains a million blue stars that are twice as hot as similar stars in the Milky Way galaxy. Only visible through gravitational lensing by a closer cluster of galaxies, the Arc is a feature of the early days of the universe, when "furious firestorms of star birth" were more common. It may be going through a short-lived luminous phase that may have lasted for as little as a few million years (Fosbury et al., 2003, in pdf).
The surface temperature of the stars in the Lynx Arc is estimated to be around 80000 K, about twenty times as hot as stars in our neighborhood. Only the stars formed directly after the Big Bang (Population III stars) are considered to be hotter (around 120000 K). The universe was only 2 billion years old at the time at which we are observing the Lynx Arc. The first stars were born 1.8 billion years before the Lynx Arc.


Beta Ophiuchi

Beta Ophiuchi (β Ophiuchi, abbreviated Beta Oph, β Oph), also named Cebalrai , is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude of this star is 2.7, which is readily visible to the naked eye even from urban skies. The distance to this star can be estimated using parallax measurements, yielding a value of from the Sun.
Nomenclature.
"β Ophiuchi" (Latinised to "Beta Ophiuchi") is the star's Bayer designation.
It bore the traditional names "Cebalrai", "Celbalrai", "Cheleb" and "Kelb Alrai" (or sometimes just "Alrai"), all derived from the Arabic كلب الراعي "kalb al-rā‘ī" "the shepherd's dog". 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 "Cebalrai" for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.
Namesake.
USS Cheleb (AK-138) was a United States Navy Crater class cargo ship named after the star.
Properties.
This is a giant star with a stellar classification of K2 III. Although it is only 13% greater in mass than the Sun, it has reached a stage in its evolution where the atmosphere has expanded to about 12 times the Sun's radius and is radiating 63 times the luminosity of the Sun. Its outer envelope is relatively cool with an effective temperature of 4,467 K, giving it the orange hue typical of K-type stars. Like some other K-type giants, β Ophiuchi has been found to vary very slightly (0.02 magnitudes) in brightness.,
Cebalrai is a member of the thin disk population. It is following a low eccentricity orbit through the Milky Way galaxy that carries it between a distance of from the Galactic Center and up to above or below the galactic plane.
Possible planetary system.
Radial velocity variations with a period of 142 days hint about the possible presence of a planetary companion orbiting Beta Ophiuchi. Thus far, no planetary object has been confirmed; while periodic radial pulsations caused by intrinsic stellar variability could explain the observed variations.


List of stars in Microscopium

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


Pi3 Orionis

Pi3 Orionis (π3 Orionis, abbreviated Pi3 Ori, π3 Ori), also named Tabit , is a star in the equatorial constellation of Orion. At an apparent visual magnitude of 3.16, it is readily visible to the naked eye and is the brightest star in the lion's hide (or shield) that Orion is holding. As measured using the parallax technique, it is distant from the Sun.
Nomenclature.
"π3 Orionis" (Latinised to "Pi3 Orionis") is the system's Bayer designation.
It bore the traditional name of 'Tabit', from the Arabic الثابت "al-thābit" 'the endurer (the fixed/constant one)'. 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 "Tabit" for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Banner of Three Stars", refers to an asterism consisting of π3 Orionis, ο1 Orionis, ο2 Orionis, 6 Orionis, π1 Orionis, π2 Orionis, π4 Orionis, π5 Orionis and π6 Orionis. Consequently, the Chinese name for Pi3 Orionis itself is (), "the Sixth Star of Banner of Three Stars".
According to "Richard Hinckley Allen: Star Names — Their Lore and Meaning", this star, together with ο1 Orionis, ο2 Orionis, π1 Orionis, π2 Orionis, π4 Orionis, π5 Orionis, π6 Orionis and 6 Orionis (are all of the 4th to the 5th magnitudes and in a vertical line), indicate the lion's skinwere but Al Tizini said that they were the Persians' "Al Tāj", "the Crown", or "Tiara", of their kings; and the Arabians' "Al Kumm", "the Sleeve" of the garment in which they dressed the Giant, the skin being omitted. Ulug Beg called them "Al Dhawāib", "Anything Pendent"; and the Borgian globe had the same, perhaps originated it. Al Sufi's title was "Manica", a Latin term for a protecting Gauntlet; and Grotius gave a lengthy dissertation on the "Mantile"' which some anonymous person applied to them, figured as a cloth thrown over the Giant's arm.
Properties.
Pi3 Orionis is most likely single; a nearby star is probably an optical companion.
It is a main sequence star of spectral type F6 V. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Compared to the Sun, it has about 124% of the mass, 132% of the radius, and nearly 3 times the luminosity. This energy is being radiated from the star's outer atmosphere at an effective temperature of 6,516 K, giving it the yellow-white glow of an F-type star.
Although a periodicity of 73.26 days has been observed in the star's radial velocity, it seems likely to be bound more to stellar activity than to a planetary object in close orbit. No substellar companion has been detected so far around Pi3 Orionis and the McDonald Observatory team has set limits to the presence of one or more planets with masses between 0.84 and 46.7 Jupiter masses and average separations spanning between 0.05 and 5.2 astronomical units. Thus, so far it appears that planets could easily orbit in the habitable zone without any complications caused by a gravitationally perturbing body.


S Pictoris

S Pictoris is a Mira variable-type star in the constellation Pictor. It ranges between apparent magnitude 6.5 and 14.0, and spectral types M6.5e to M8III-IIe, over a period of 422 days.


74 Virginis

74 Virginis is a single star in the zodiac constellation of Virgo. It is visible to the naked eye as a faint red-hued star with an apparent visual magnitude of 4.69. The star is positioned near the ecliptic and thus is subject to lunar occultations. The measured annual parallax of provides a distance estimate of around 400 light years from the Sun. At that range, the visual magnitude of the star is diminished by an extinction of due to interstellar dust. It is moving further from the Earth with a heliocentric radial velocity of +19 km/s.
This is an aging red giant star with a stellar classification of M2.5 III, which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. It is a suspected variable star that may vary in brightness with an amplitude of 0.07 in magnitude. The star is roughly 2.9 billion years old with 1.4 times the mass of the Sun and has expanded to around 78 times the Sun's radius. 74 Virginis is radiating 832 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,500 K.


Kappa Virginis

Kappa Virginis (κ Virginis, abbreviated Kappa Vir, κ Vir), officially named Kang , is a solitary star in the zodiac constellation of Virgo. It has an apparent visual magnitude of 4.18, which is sufficiently bright to be seen with the naked eye. Based upon stellar parallax measurements, the distance to this star is about 255 light-years.
Nomenclature.
"κ Virginis" (Latinised to "Kappa Virginis") is the star's Bayer designation.
In Chinese, (), meaning "Neck", refers to an asterism consisting of Kappa Virginis, Iota Virginis, Phi Virginis and Lambda Virginis. Consequently, Kappa Virginis itself is known as (), "the First Star of Neck".
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 "Kang" for this star on 30 June and it is now so included in the List of IAU-approved Star Names.
Properties.
This is an orange-hued K-type giant star with a stellar classification of K2/3 III. It has about 146% of the mass of the Sun, but at an estimated age of 9.7 billion years it has evolved and expanded to over 25 times the Sun's radius. As a consequence, it shines with around 229 times the solar luminosity. The effective temperature of the star's outer atmosphere is 4,235 K.


List of stars in Canis Minor

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


BP Circini

BP Circini is a binary star system in the southern constellation of Circinus. It is located at a distance of approximately 3,300 light years from the Sun based on parallax.
The variability of this star was discovered by D. W. Kurtz in 1979. A small-amplitude Cepheid variable, its apparent magnitude ranges from 7.37 to 7.71 over 2.39810 days. A spectroscopic binary, the primary is a yellow-white bright giant of spectral type F2 or F3II. The spectrum shows peculiarities in the metallic lines. The secondary is a 4.7 solar mass () blue-white main sequence star of spectral type B6.


Delta Sculptoris

Delta Sculptoris (δ Scl, δ Sculptoris) is a triple star system in the constellation Sculptor. It is approximately 137.4 light years from Earth.
The primary component, Delta Sculptoris A, is a white A-type main sequence dwarf with an apparent magnitude of +4.59. It has a faint, 11.6 magnitude companion, Delta Sculptoris B, 4 arcseconds, or more than 175 astronomical units, away from it. Orbiting this pair at the much greater separation of 74 arcseconds, is the yellow G-type Delta Sculptoris C, which has an apparent magnitude of +9.4.
This system is a candidate member of the AB Doradus moving group, an association of stars with similar ages that share a common heading through space.


NGC 485

NGC 485, also commonly referred to as PGC 4921 or GC 270, is a spiral galaxy in the constellation Pisces. It is located approximately 86 million light-years from Earth and was discovered on January 8, 1828 by astronomer William Herschel. It was later also observed by Heinrich d'Arrest and Herman Schultz. When NGC 485 was originally categorized in the New General Catalogue by John Louis Eil Dreyer in 1888, it was incorrectly described as a "considerably faint, pretty large, round, 8th magnitude star 3 1/2 arcmin to southwest".


Lambda Virginis

Lambda Virginis (λ Virginis, abbreviated Lambda Vir, λ Vir) is a binary star system in the zodiac constellation of Virgo. With an apparent visual magnitude of 4.5, it is bright enough to be seen with the naked eye. Based upon parallax measurements, the system is about 173 light-years away from the Sun. Its two components are designated Lambda Virginis A (formally named Khambalia ) and B.
Nomenclature.
"λ Virginis" (Latinised to "Lambda Virginis") is the system's Bayer designation. The designations of the two components as "Lambda Virginis A" and "B" derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
The system occurs in the lunar station that was given the name χαμβαλια ("khambalia")
in a Coptic manuscript list of lunar stations, which Crum concluded were either in "debased" Greek or in a few cases Coptic equivalents of Greek names. Given that the Greeks are not known to have used lunar stations, the origin of the names is unknown.
Allen's source
translates the name as "the crooked-clawed", and identifies it with the Greek word γαμψωλή "gampsôlê", which Liddell & Scott identify as a variant of γαμψότης "gampsotês" ""crookedness", of talons". (Coptic has no sound, and so often substitutes "k" for "g" in Greek words, though not usually "kh".)
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 "Khambalia" for the component Lambda Virginis A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.
In China, (), meaning "Neck", refers to an asterism consisting of this system, Kappa Virginis, Iota Virginis and Phi Virginis. Consequently, Lambda Virginis itself is known as (, .)
Properties.
Lambda Virginis is a double-lined spectroscopic binary with an orbital period of 206.7 days and an eccentricity of 0.0610. The semi-major axis has an angular size of 0.02 arcseconds, which, at the distance of this system, is equivalent to a physical span of  AU. The orbit is inclined by an angle of 110° to the line of sight from the Earth. Tidal theory predicts that eventually the orbit of the stars will circularize and their rotation rates will become synchronized with their orbital motion. However, this will occur over a time scale of more than 1.2 billion years, whereas their estimated age is 935 million years.
The combined spectra of the two components has a stellar classification of A1V, which matches an A-type main-sequence star. They have magnitudes of +5.0 and +5.6. Both components are Am stars, indicating they appear chemically peculiar. The primary appears to be rotating around 3.5 times faster than the secondary.


Epsilon Herculis

Epsilon Herculis, Latinized from ε Herculis, is a fourth-magnitude multiple star system in the northern constellation of Hercules. The combined apparent visual magnitude of 3.9111 is bright enough to make this system visible to the naked eye. Based upon an annual parallax shift of 21.04 mas as seen from Earth, it is located 155 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −25 km/s.
There is disagreement over the properties of this system. Petrie (1939) classified two components as class A0 and A2 with a visual magnitude difference of 1.5. Batten et al. (1989) catalogued it as a double-lined spectroscopic binary system with an orbital period of four days and an eccentricity of 0.02. However, Hipparcos was not able to detect the duplicity. Tokovinin (1997) and Faraggiana et al. (2001) catalogued it as a triple star system. Cowley et al. (1969) gave it a combined stellar classification of A0 V, whereas Gray & Garrison (1987) classified it as an A0 IV+. Wolff & Preston (1978) listed a magnesium overabundance. Since 1995 it has been classified as a Lambda Boötis star, although this has been brought into question.
In Chinese, (), meaning "Celestial Discipline", refers to an asterism consisting of ε Herculis, ξ Coronae Borealis, ζ Herculis, 59 Herculis, 61 Herculis, 68 Herculis, HD 160054 and θ Herculis. Consequently, the Chinese name for ε Herculis itself is (, .)


Upsilon Scorpii

Upsilon Scorpii (υ Scorpii, abbreviated Upsilon Sco, υ Sco), formally named Lesath , is a star located in the "stinger" of the southern zodiac constellation of Scorpius, the scorpion. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 580 light-years from the Sun. In the night sky it lies near the 1.6 magnitude star Lambda Scorpii, and the two form an optical pair that is sometimes called the "Cat's Eyes".
Nomenclature.
"υ Scorpii" (Latinised to "Upsilon Scorpii") is the star's Bayer designation.
It bore the traditional name "Lesath" (alternatively spelled "Leschath", "Lesuth"), from the Arabic "las'a" "pass (or bite) of a poisonous animal"; but this is a miscorrection by Scaliger (a European astronomer who knew Arabic) for earlier "Alascha", which came from Arabic "al laţkha" "the foggy patch", referring to the nearby open cluster M7. 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 "Lesath" for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.
Together with Lambda Scorpii (Shaula), Lesath is listed in the Babylonian compendium MUL.APIN as dSharur4 u dShargaz, meaning "Sharur and Shargaz". In Coptic, they were called "Minamref" The indigenous Boorong people of northwestern Victoria named it as "Karik Karik" (together with Lambda Scorpii), "the Falcons"
In Chinese, (), meaning "Tail", refers to an asterism consisting of Upsilon, Mu1, Epsilon, Zeta1, Zeta2, Eta, Theta, Iota1, Iota2, Kappa, and Lambda Scorpii. Consequently, the Chinese name for Upsilon Scorpii itself is (), "the Ninth Star of Tail".
Namesake.
USS Lesuth (AK-125) was a United States Navy Crater class cargo ship named after the star.
Properties.
This star has apparent magnitude +2.7 and belongs to spectral class B2 IV, with the luminosity class of 'IV' indicating it is a subgiant star. The star's luminosity is 12,300 times that of the Sun, while its surface temperature is 22,831 kelvins. The star has a radius of 6.1 times solar and 11 times the mass of the Sun.


Omega Tauri

The Bayer designation Omega Tauri (ω Tau, ω Tauri) is shared by two star systems, ω1 Tauri and ω2 Tauri, in the constellation Taurus. They are separated by 2.13° on the sky.


Gliese 806

Gliese 806 is a star in the northern constellation of Cygnus, located about a degree to the southeast of the bright star Deneb. It is invisible to the naked eye with an apparent visual magnitude of +10.79. The star is located at a distance of 39.3 light years from the Sun based on stellar parallax. It is drifting closer with a radial velocity of −24.6 km/s, and is predicted to come to within in ~198,600 years. The star is suspected to host a substellar companion yet unconfirmed.
The stellar classification of Gliese 806 is dM1.5, which indicates this is a small red dwarf star – an M-type main-sequence star that is generating energy through core hydrogen fusion. It is roughly three billion years old and is spinning with a projected rotational velocity of 0.46 km/s. The star has 42% of the mass and radius of the Sun. It is radiating 0.3% of the luminosity of the Sun from its photosphere at an effective temperature of 3,586 K.
Candidate companion.
In 1989, Marcy and Benitz detected a periodicity of 416 days in radial velocity variation, inferring the possible presence of a companion with mass of about . This candidate object has not yet been confirmed.


NGC 3640

NGC 3640 is an elliptical galaxy located in the constellation Leo. It is located at a distance of circa 75 million light years from Earth, which, given its apparent dimensions, means that NGC 3640 is about 90,000 light years across. It was discovered by William Herschel on February 23, 1784. It lies 2 degrees south of Sigma Leonis and is a member of the Herschel 400 Catalogue. It is condensed and can be spotted with a small telescope from suburban skies.
Characteristics.
NGC 3640 is an elliptical galaxy with a highly disturbed stellar component. The galaxy features boxy isophotes, and patchy shell-like features. These features indicate a recent merger with a smaller gas-poor galaxy. A dust lane is observed along the minor-axis, spanning 30 arcseconds in a north-south direction. The galaxy has a high rotational velocity, estimated to be 120 ± 10 km/s, higher than that of other elliptical galaxies of similar luminosity. The HI mass of the galaxy is estimated to be and the mass of HII less than .
In the centre of NGC 3640 lies a supermassive black hole whose mass is estimated to be roughly 100 million (107.99 ± 0.39) based on the Sérsic profile.
Nearby galaxies.
NGC 3640 is the foremost galaxy in a galaxy group known as the NGC 3640 group. Other members of the group include NGC 3630, NGC 3641, NGC 3643, and NGC 3664. NGC 3640 forms a pair with NGC 3641, which lies 2.5 arcminutes south from NGC 3640. The group belongs to the Leo II groups, a large collection of galaxies belonging to the Virgo supercluster scattered across 30 million light years of space west of the Virgo cluster.


26 Draconis

26 Draconis is a triple star system in the constellation Draco, located 46 light years from the Sun. Two of the system components, A and B, form a spectroscopic binary that completes an orbit every 76 years. The composite spectral classification of the AB pair is G0V, which decomposes to individual spectral types F9V and K3V. A 1962 study estimated the masses of these two stars as 1.30 and 0.83 times the mass of the Sun, respectively. The stars are considered moderately metal-poor compared to the Sun, which means they have a lower proportion of elements other than hydrogen or helium.
Gliese 685.
The third component, GJ 685, is a red dwarf spectral classification of M0V. As of 1970, this star is separated by 737.9 arc seconds from the AB pair and they share a common proper motion. The Star GJ 685 has one known planet orbit that was detected by radial velocity.
The space velocity components of 26 Draconis are U = +36.5, V = −4.3 and W = −21.8 km/s. This system is on an orbit through the Milky Way galaxy that has an eccentricity of 0.14, taking it as close as and as far as from the galactic core. The inclination of this orbit carries the star system as much as above the plane of the galactic disk. This system may be a member of the Ursa Major moving group.


OU Geminorum

OU Geminorum (OU Gem) is a visual binary or possible triple star located in the constellation of Gemini.
The system has an absolute magnitude of 5.93, so at a distance of 48 light years it has an apparent magnitude of 6.77 when viewed from earth. It also has a total Proper Motion of 0.210"/yr and belongs to the Ursa Major stream.
The system is a much studied BY Draconis variable star with a period of 6.99 days The primary star has a spectral type of K3Vk. The secondary star in the system has a surface temperature of and orbits the primary in about seven days.


56 Cygni

56 Cygni is a single star in the northern constellation of Cygnus, located 135 light years from Earth. It is visible to the naked eye as a white-hued star with an apparent visual magnitude of 5.06. The star is moving closer to the Earth with a heliocentric radial velocity of −21.5. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of /yr. According to Eggen (1998), this is a member of the Hyades Supercluster.
This is an A-type main-sequence star with a stellar classification of A6 V. Cowley et al. (1969) classified it as a Delta Delphini star, which is a type of suspected Am star. The star is around 394 million years old with a projected rotational velocity of 73 km/s. It has 1.72 times the mass of the Sun and is radiating 13 times the Sun's luminosity from its photosphere at an effective temperature of 8,124 K.
56 Cygni has a visual companion: a magnitude 11.9 star at an angular separation of along a position angle of 48°, as of 2015.