LHS 2520

LHS 2520, also known as Gliese 3707, is a red dwarf star in the constellation Corvus. With an apparent magnitude of 12.12. it is too faint to be seen with the unaided eye. A cool star of spectral type M3.5V, it has a surface temperature of 3024 K. The star was too faint to have had its parallax measured by the "Hipparcos" satellite. Earth-based measurement gives its parallax as 77.93 ± 2.41 milliarcseconds, yielding a distance of 42 ± 1 light-years.
In Popular Culture.
In "Action Comics" #14 (January 2013), which was published 7 November 2012, Neil Degrasse Tyson appears in the story, in which he determines that Superman's home planet, Krypton, orbited LHS 2520. Tyson assisted DC Comics in selecting a real-life star that would be an appropriate parent star to Krypton, and picked the star in Corvus, and which is the mascot of Superman's high school, the Smallville Crows.
The Star also appears as LP 734-32 in the 2014 game, Elite Dangerous.


B Persei

b Persei (also known as HD 26961) is a spectroscopic triple star in the constellation Perseus. Its apparent magnitude is 4.60, and it is about 320 light years away.
In addition to the primary, an A-type giant, there is a smaller and cooler companion in a 1.53 day orbit, probably an F-class star around absolute magnitude 3.0, and a more distant companion in a 702-day orbit.


Xi Capricorni

The Bayer designation Xi Capricorni (ξ Cap, ξ Capricorni) is shared by two star systems, in the constellation Capricornus:
They are separated by 0.25° in the sky.


Heart (Chinese constellation)

The Heart mansion (心宿, pinyin: Xīn Xiù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the eastern mansions of the Azure Dragon. Its prominent figure is the star Alpha Scorpii.


B Velorum

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


Tau3 Eridani

Tau3 Eridani, Latinized from τ3 Eridani, is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.10. Using the parallax method, the distance to this star can be estimated as 88.6 light years. In 2001 it was reported as a candidate Vega-like star, meaning it appears to radiate an infrared excess from an orbiting circumstellar disk. However, this has not been confirmed.
This is an A-type star with a stellar classification of A3 IV-V. The luminosity class of IV-V indicates the spectrum displays traits intermediate between a main sequence and subgiant star. It is around 476 million years old and is spinning rapidly with a projected rotational velocity of 133 km/s. This is creating an equatorial bulge that might be 7% wider than the polar radius. Tau3 Eridani has 178% of the Sun's mass and nearly double the radius of the Sun. The star shines with 13.7 times the solar luminosity from an outer atmosphere at an effective temperature of 8,251 K.


Beta Carinae

Beta Carinae (Latinised from β Carinae, abbreviated Beta Car, β Car), officially named Miaplacidus , is the second-brightest star in the constellation of Carina and one of the brightest stars in the night sky, with apparent magnitude 1.68. It is the brightest star in the southern asterism known as the Diamond Cross, marking the southwestern end of the asterism. It lies near the planetary nebula IC 2448. Parallax measurements place it at a distance of from the Sun.
Nomenclature.
"β Carinae" (Latinised to "Beta Carinae") is the star's Bayer designation.
The star's historical name "Miaplacidus" made its debut on star maps in 1856 when the star atlas "Geography of the Heavens", composed by Elijah Hinsdale Burritt, was published. The meaning and linguistic origin of the name remained an enigma for many decades, until William Higgins, a great scholar and expert on star names, surmised that the name "Miaplacidus" is apparently a bilingual combination of Arabic "مياه" "miyāh" for 'waters' and Latin "placidus" for 'placid'. The IAU Working Group on Star Names first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Miaplacidus" for this star.
In Chinese, (), meaning "Southern Boat", refers to an asterism consisting of β Carinae, V337 Carinae, PP Carinae, θ Carinae and ω Carinae. Consequently, β Carinae itself is known as (, .)
Physical properties.
The stellar classification of A1 III suggests this is an evolved giant star, although Malagnini and Morossi (1990) rated it as an A2 IV subgiant star. It has an estimated age of 260 million years. This star does not show an excess emission of infrared radiation that might otherwise suggest the presence of a debris disk. It has about 3.5 times the Sun's mass and has expanded to almost seven times the radius of the Sun. Presently is it radiating 288 times as much luminosity as the Sun from its outer envelope at an effective temperature of 8,866 K. Despite its enlarged girth, this star still shows a rapid rotation rate, with a projected rotational velocity of .


NGC 5466

NGC 5466 is a class XII globular cluster in the constellation Boötes. Located 51,800 light years from Earth and 52,800 light years from the galactic center, it was discovered by William Herschel on May 17, 1784, as H VI.9. This globular cluster is unusual insofar as it contains a certain blue horizontal branch of stars, as well as being unusually metal poor like ordinary globular clusters. It is thought to be the source of a stellar stream discovered in 2006, called the "45 Degree Tidal Stream". This star stream is an approximately 1.4° wide star lane extending from Boötes to Ursa Major.


NGC 5562

NGC 5562 is a spiral galaxy (class S) in the constellation of Boötes.


HR 8442

HR 8442 is a spectroscopic binary star in the constellation Cepheus. The primary is a G type giant star while the secondary's spectral type is unknown.
The spectroscopic binary nature of the star was first noticed by Jose Renan de Medeiros and Michel Mayor using radial velocity measurements from the Coravel spectrometer at Haute-Provence Observatory. Roger Griffin then placed the star on his observing program at Cambridge Observatory leading to an orbital solution being published in 2015.


NGC 4444

NGC 4444 is an intermediate spiral galaxy in the constellation Centaurus. The morphological classification places it midway on the continuum between a barred spiral (SB) and an unbarred spiral (SA), with an inner region that lies between a ring-like ("r") and a purely spiral form ("s"), and medium- ("b") to loosely wound ("c") outer spiral arms. This makes it a hybrid ringed, barred spiral galaxy. It has an angular size of and the estimated mass "M" is given log "M" = 9.76, yielding solar masses.


HR 6594

HR 6594 is the "Bright Star Catalogue" designation for a binary star system in the northern constellation of Hercules. It is faintly visible to the naked eye with an apparent visual magnitude of 5.55; according to the Bortle scale, it is sufficiently bright to be visible from dark suburban skies. The distance to this system, as determined using parallax measurements, is about 114 light years. On the celestial sphere it is located near the star Alpha Ophiuchi; their projected separation is just 3 light years, although their actual separation is much greater.
The primary is an F-type main sequence star with a stellar classification of F4 Vw, where the "w" indicates relatively weak metallic features in the ultraviolet spectrum. This star has 134% of the Sun's mass, but only 97% of the solar radius. It is spinning with a projected rotational velocity of 31.7 km/s, and is around 1.2 billion years old. The effective temperature of the outer atmosphere is 6,615 K, giving it the yellow-white hue of an F-type star. The abundance of elements other than hydrogen or helium, what astronomers term the metallicity, is similar to that in the Sun.
It has a magnitude 9.38 companion star orbiting with a 144-year period, a semimajor axis spanning 1.04 arcseconds, and an eccentricity of 0.42. There is a third, visual companion of magnitude 14.46 at an angular separation of 154.70 arcseconds along a position angle of 271°, as of 2001.


66 Arietis

66 Arietis (abbreviated 66 Ari) is a double star in the northern constellation of Aries. "66 Arietis" is the Flamsteed designation. It has an apparent visual magnitude of 6.03, putting it near the limit for naked eye visibility. The magnitude 10.4 companion is located at an angular separation of 0.810 arcseconds from the primary along a position angle of 65°. The distance to this pair, as determined from parallax measurements made during the Hipparcos mission, is approximately .
The spectrum of the primary component matches a stellar classification of K0 IV, with the luminosity class of IV indicating this is a subgiant star. It has 6 times the radius of the Sun and shines with 18 times the Sun's energy. This energy is radiated from the outer atmosphere at an effective temperature of 4,864 K, giving it the cool orange-hued glow of a K-type star.


42 Capricorni

42 Capricorni is a binary star system in the zodiac constellation of Capricornus. It has a combined apparent visual magnitude of 5.18, so it is faintly visible to the naked eye. Its annual parallax shift of 30.09 mas yields a distance estimate of about 108 light years; the system is moving closer to the Sun with a radial velocity of −1.2 km/s. 42 Capricorni is 0.2 degree south of the ecliptic and so is subject to lunar occultations.
This is a double-lined close spectroscopic binary with an orbital period of 13.174 days and an eccentricity of 0.18. The binary nature of this system was discovered in 1918 by the English astronomer Joseph Lunt. It has a combined spectrum that matches a stellar classification of G1 IV, with the individual components having estimated classes of G1 V and G2 V. This is an RS Canum Venaticorum variable, indicating the presence of an active chromosphere with star spots. The system is a source of X-ray emission.


60 Leonis

60 Leonis is a star in the zodiac constellation of Leo, located 127 light years from the Sun. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.4. The star is moving closer to the Earth with a heliocentric radial velocity of −11 km/s.
This is an Am star with a stellar classification of A1 Vm, although LeBlanc et al. (2015) consider it an Ap star. The atmosphere displays clear indications of stratification of iron with no significant magnetic field detected. It is 195 million years old with a relatively low projected rotational velocity of 17 km/s. The star has 2.11 times the mass of the Sun and 1.80 times the Sun's radius. It is radiating 24.1 times the Sun's luminosity from its photosphere at an effective temperature of 9,540 K.


NGC 6445

NGC 6445, also known as the Little Gem Nebula or Box Nebula, is a planetary nebula in the constellation Sagittarius. It was discovered by William Herschel on May 28, 1786. The distance of NGC 6445 is estimated to be slightly more than 1,000 parsecs based on the parallax measured by Gaia, which was measured at mas.
Characteristics.
NGC 6445 has been classified as a bipolar planetary nebula. Its He/H and N/O abundance ratios are consistent with the Type I definition. In optical images, NGC 6445 features a bright, central ring-shaped morphology and open bipolar lobes; the outer envelope emission of NGC 6445 is [N ii]-dominant.
Wide-field optical images obtained by the Nordic Optical Telescope (NOT) Andalucía Faint Object Spectrograph and Camera (ALFOSC) show that NGC 6445 has an irregularly shaped central region with a size of ~40" × 50", where the [O iii] emission dominates, while the [N ii] emission is much more extended and defines an overall bipolar morphology. The bipolar lobes are along the east–west (EW) direction with position angle ~ 80°, stretching to about 1'.6 from the center. There are also many filamentary structures across the nebula, which hint at a more complex morphology of NGC 6445. The breadths of the EW lobes reach ~1'.8 at both ends. This means given the distance of NGC 6445 that the nebula is 4 light years across and is among the largest known. NGC 6445 has a faint halo, seen in residual H2 emission images, which show filamentary features well outside the central region along the north–south (NS) direction. These filaments are located ~1'.3 – 1'.6 from the center. The southern filaments are more extended along the EW direction. There are also rays of faint emission coming from the central region.
A close comparison of the residual H2 image against the Spitzer IRAC 8.0 μm and the NOT ALFOSC [N ii] images shows that along NS direction the H2 emission generally delineates the outer boundary of a broad region where the 8.0 μm emission dominates, while the [N ii] emission is more extended along the EW direction, consistent with the bipolar morphology, and is confined within the 8.0 μm-emitting region along the north-south direction. Along this direction, the H2 emission appears to be slightly farther out than the [N ii] emission. This reinforces the notion that the optical emission may be significantly affected by the illumination of UV photons and cannot represent the intrinsic matter distribution of PNe. The [N ii] image mainly traces the bipolar lobes, while the H2 image reveals the limb-brightened gas extended along the equatorial direction.
The northern and the southern H2-emitting filaments, ~1'.4 – 1'.6 from the center of NGC 6445, might be the outer boundaries of an edge-on-viewed torus of this PN. This torus was ejected in the AGB phase, when the projenitor star was a red giant, and is now being disrupted by interaction with the fast stellar wind that was developed later. The south region of the torus seems to be much more disrupted than its north counterpart. Within the EW bipolar lobes, there seem to be two arcs in the H2 emission, as shown in the residual image: a northeast (NE) arc and a southwest (SW) one, both ~1'.0 from the nebular center. The SW arc seems to be disrupted but matches the position of a giant arc in [N ii]. These two H2 arcs might define another pair of bipolar lobes, which have a PA ~ 56°. This PA generally agrees with that of the [O iii]-right inner nebular region of NGC 6445, suggesting that the smaller bipolar bubbles are of relatively higher excitation and thus might have developed recently.
Observation.
NGC 6445 lies 2.1 degrees southwest from the open cluster Messier 23. NGC 6445 can be located by star hopping from Messier 23, by firstly locating an arc of 7th and 8th magnitude stars one degree southwest of M23, with the nebula lying 5 arcminutes west of an 8th magnitude star that lies 40 arcminutes west of the southernmost star of the arc. The globular cluster NGC 6440 lies 23 arcminutes to the south and both ojects can be seen in a wide field eyepiece. In low magnification the nebula appears like a fuzzy star and higher magnifications reveal its rectangular disk. The planetary nebula is included in the Herschel 400 Catalogue.


38 Geminorum

38 Geminorum is a binary star system in the northern zodiac constellation of Gemini. It has the Bayer designation e Geminorum, while "38 Geminorum" is the Flamsteed designation. This system is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.71. The primary component is a magnitude 4.75 star, while the secondary is magnitude 7.80. The system is located about 98 light years away from the Sun based on parallax, and is drifting further away with a radial velocity of +16 km/s. It is a potential member of the Tucana–Horologium stellar kinematic group.
This is a wide binary system with a projected separation of . Two sets of low quality orbital elements have been computed for this system, yielding periods of and , and eccentricities of 0.150 and 0.485, respectively. As of 2018, the pair had an angular separation of along a position angle of 143°.
Abt and Morrell (1995) classified the primary component as an A-type main-sequence star with a stellar classification of A8V. It is a suspected chemically peculiar star of subtype CP1 (an Am star), which Slettebak (1955) classified as kA8mF0Vp. This notation indicates the star displays the calcium K line of an A8 star and the metal lines of an F0V star. In 1949, J. Hopmann catalogued it as a suspected Delta Scuti variable. The secondary is a G-type main-sequence star with a class of G6V.


Tau5 Serpentis

Tau5 Serpentis, Latinized from τ5 Serpentis, is a F-type main sequence star in the constellation of Serpens, approximately 160 light-years from Earth. It has an apparent visual magnitude of approximately 5.938.


VZ Arietis

VZ Arietis is single, white-hued star in the northern zodiac constellation of Aries. Varying between magnitudes 5.82 and 5.89, the star can be seen with the naked eye in dark, unpolluted areas. Based upon an annual parallax shift of , it is located 560 light years from the Sun. It is moving further away with a heliocentric radial velocity of +14 km/s. The star was formerly known as 16 Trianguli, but as the star is no longer in the constellation Triangulum, this designation has fallen out of use.
This is a chemically peculiar star of type CP2 (Ap star), showing an anomalous abundance of silicon in its spectrum. It has a stellar classification of A0 V, which indicates this is an A-type main-sequence star that currently fusing hydrogen into helium in its core. This is an Alpha2 Canum Venaticorum variable with 2.7 times the mass of the Sun and about 3.1 times the Sun's radius. It is radiating 79 times the Sun's luminosity from its photosphere at an effective temperature of 10,304 K.


HD 86264

HD 86264 is a 7th magnitude F-type main sequence star located approximately 224 light years away in the constellation Hydra.
The survey in 2015 have ruled out the existence of any stellar companions at projected distances above 30 astronomical units.
Planetary system.
In August 2009, it was announced that an exoplanet was found in an eccentric orbit.


42 Persei

42 Persei is a binary star system in the northern constellation of Perseus. It has the Bayer designation n Persei, while "42 Persei" is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.11. It is located around distant from the Sun, but is drifting closer with a radial velocity of −12.4 km/s.
42 Persei is a single-lined spectroscopic binary with an orbital period of 1.77 days and an eccentricity of just 0.056. It is a variable star, ranging in brightness from magnitude 5.05 to 5.18, and was assumed at discovery to be a close, but detached, eclipsing variable. Closer studies of the light variations and the orbit have shown that the main brightness changes are due to rotation of the distorted primary star, although it is predicted from the likely inclination of the orbit that shallow eclipses could also occur.
The visible component is an A-type main-sequence star with a stellar classification of A3V; a star that is fusing its core hydrogen. It has been reported as a mild Am star, but this is considered questionable. The star has twice the mass of the Sun and 3.5 times the Sun's radius. It has a high rate of spin, showing a projected rotational velocity of 91 km/s. The star is radiating 59 times the luminosity of the Sun from its photosphere at an effective temperature of 8,892 K. The unseen companion star is likely to be a dim red dwarf with 38% of the Sun's mass.
In Chinese astronomy, 42 Persei is called 天讒, Pinyin: Tiānchán, meaning "Celestial Slander", because this star is marking itself and stand alone in "Celestial Slander" asterism, Hairy Head mansion (see : Chinese constellation).


24 Cancri

24 Cancri (abbreviated to 24 Cnc) is a triple star system in the constellation Cancer. The system is located about 260 light-years (80 parsecs) away, based on its parallax. The system has a combined apparent magnitude of 6.91.
The primary component in the star system is designated 24 Cancri A. It is a F-type giant star. The secondary component, designated 24 Cancri B, is a F-type main-sequence star. It itself is a binary, with an orbital period of about 22 years.


Kappa Cancri

Kappa Cancri, Latinized from κ Cancri, is a blue-white hued binary star system in the zodiac constellation of Cancer. It is faintly visible to the naked eye with an apparent visual magnitude of +5.23. The magnitude difference between the two stars is about 2.6. Based upon an annual parallax shift of 7.13 mas as seen from the Earth, the system is located roughly 460 light years from the Sun.
This is a single-lined spectroscopic binary star system with an orbital period of 6.39 days and an eccentricity of 0.13. The primary, component A, has a stellar classification of B8 IIIp, suggesting it is a B-type giant star. It a mercury-manganese star, a type of chemically peculiar star showing large overabundances of those two elements in the outer atmosphere. It is classified as an Alpha2 Canum Venaticorum type variable star and its brightness varies from magnitude +5.22 to +5.27 with a period of 5 days.
The primary component has 4.5 times the mass of the Sun, 5 times the Sun's radius, and an effective temperature of 13,200 K. The secondary, component B, is a smaller star with 2.1 times the mass and 2.4 times the radius of the Sun, having an effective temperature of 8,500 K.


HD 30453

HD 30453 is a binary star system in the northern constellation of Auriga. It is visible to the naked eye with an apparent visual magnitude of 5.86. The system is located at a distance of approximately 334 light years from the Sun based on parallax. It is drifting further away from the Sun with a radial velocity of 16.65 km/s.
This is a double-lined spectroscopic binary system with an essentially circular orbit and a period of one week. The primary component is a chemically peculiar star of type CP1, or Am star, with a stellar classification of A8m. Abt and Morrell (1995) classed it as Am(A7/F0/F2), indicating it has the hydrogen lines of an A7 star, the calcium K line of a cooler F0 star, and the metallic kines of an F2 class. It has been mentioned as a potential variable star. The star has 3.6 times the girth of the Sun and is radiating 38 times the Sun's luminosity from its photosphere at an effective temperature of 7568 K. It has a moderate rotation rate, with a projected rotational velocity of around 16 km/s.
A third component was detected in 1987 using speckle interferometry at an angular separation of .


List of stars in Pictor

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


Mu Scorpii

The Bayer designation Mu Scorpii (μ Sco, μ Scorpii) is shared by two star systems, in the constellation Scorpius:
They are separated by 0.1° in the sky.
They are separated too into different asterism in Chinese astronomy. μ¹ Scorpii was a member of asterism 尾 (Wěi), "Tail" and μ² Scorpii was the sole star in asterism 神宮 (Shéngōng), "Changing Room (of the temple)". Both asterisms are part of the "Tail" mansion.


G Carinae

The Bayer designations g Carinae and G Carinae refer to separate stars:


Gliese 809

Gliese 809 is a red dwarf star in the constellation Cepheus, forming the primary component of a multi-star system. A visual magnitude of 8.55 makes it too faint to see with the naked eye. It is part of the Gliese Catalogue of Nearby Stars and is located about 23 light-years (ly) from the Solar System. Gliese 809 has about 70.5% the radius of the Sun and 61.4% of the Sun's mass. It has a metallicity of −0.06, which means that the abundance of elements other than hydrogen and helium is just 87.1% that of the Sun.
This is a high proper motion star that moves about 0.77 arcseconds per year relative to background stars. In physical terms it is travelling with a space velocity of 31.1 km/s relative to the Solar System. The galactic orbit of this star carries it 21,300 ly from the Galactic Center at its perigee to 30,600 ly at its apogee. The orbital eccentricity is 17.8% with the semi-major axis of 25,956 ly and a semi-minor axis of 25,542 ly.


Nu3 Canis Majoris

Nu3 Canis Majoris, Latinized from ν3 Canis Majoris, is a binary star system in the southern constellation of Canis Major.
Characteristics.
The star system, appearing as one star, is deemed visible to the naked eye with its combined apparent visual magnitude of 4.41. Based upon an annual parallax shift of 7.74 mas as seen from Earth, this system is about 420 light years from the Sun, much further than Nu1 and Nu2 which appear nearby when seen from one point in our solar system.
The primary member, component A, is an evolved, orange-hued giant/bright giant hybrid with an apparent magnitude of +4.63 and a stellar classification of K0 II-III. It is most likely (96% chance) on the horizontal branch. The star has a moderate level of surface activity with a magnetic field strength of and is a source of X-ray emission with a luminosity of .
This giant has an estimated 3.4 times the mass of the Sun and has expanded to 33 times the Sun's radius. It is radiating 398 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,510 K. The star is spinning with the leisurely period of 183 days. Its companion, component B has been observed at 1.040 arcseconds distant and has an apparent magnitude of +8.56.


55 Arietis

55 Arietis is a single star in the northern zodiac constellation of Aries. "55 Arietis" is the Flamsteed designation. It is faintly visible to the naked eye as a dim, blue-white hued point of light with an apparent visual magnitude of 5.72. Based upon an annual parallax shift of , it is approximately distant from Earth, give or take a 30 light-year margin of error. Eggen (1995) listed it as a proper motion candidate for membership in the IC 2391 supercluster. It may be a runaway star, having a peculiar velocity of relative to its neighbors.
The spectrum of this star matches a B-type giant with a stellar classification of B8 III. It has a high rate of spin, showing a projected rotational velocity of 196 km/s. The star has 4.1 times the mass of the Sun but 9.5 times the Sun's radius. It is radiating 326 times as much luminosity as the Sun from its photosphere at an effective temperature of 7,961 K.


FU Orionis

FU Orionis is a variable and binary star system in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9. The name "FU Orionis" is a variable star designation in the Argelander system, which are assigned sequentially as new variables are discovered. FU Orionis is about 1,360 light years distant and is associated with the molecular cloud Barnard 35.
For a long time this variable was considered unique, but in 1970 a similar star, V1057 Cygni, was discovered, and a number of additional examples have been discovered since then. These stars constitute the FU Orionis class of variable stars, GCVS type "FU", often nicknamed "FUors". These stars are pre–main sequence stars which display an extreme change in magnitude and spectral type.
Stellar System.
FU Orionis consists of two components, both surrounded by a circumstellar disk. Both disks were resolved with ALMA. The primary is surrounded by a dust disk with a radius of 11 astronomical units and the secondary disk has a similar inclination and size. The disks are separated by about 250 au. The 12CO emission show a complex kinematic environment and signatures of disk rotation, which are asymmetric. The asymmetry of the disk rotation is explained with interactions of the disks during a stellar flyby.
The primary, called FU Orionis north has a mass of 0.6  and accretes formula_1 per year. The primary has an uncertain spectral type and luminosity class. FU Orionis stars do not show strong emission lines during the outburst and have spectral features that resemble F- or G-type supergiants during the maximum. The outer parts of FU Orionis stars produce a K-M supergiant spectrum, which can be observed in the near-infrared. The secondary, called FU Orionis south could be the more massive component in the system with 1.2 and a spectral type of about K5.
Nebula.
FU Orionis is associated with the molecular cloud Barnard 35 (part of the Lambda Orionis Ring) and close to the star an arc-shaped nebula is visible. Other FU Orionis stars are associated with an arc-shaped reflection nebula that becomes visible as the star brightens.


Delta Cygni

Delta Cygni (δ Cygni, abbreviated Delta Cyg, δ Cyg) is a binary star of a combined third-magnitude in the constellation of Cygnus. It is also part of the Northern Cross asterism whose brightest star is Deneb. Based upon parallax measurements obtained during the Hipparcos mission, Delta Cygni is located roughly distant from the Sun.
Delta Cygni's two components are designated Delta Cygni A (officially named Fawaris ) and B. More widely separated is a faint third component, a 12th magnitude star that is moving along with the others. Together they form a triple star system.
Nomenclature.
"δ Cygni" (Latinised to "Delta Cygni") is the binary's Bayer designation. The designations of the two components as "Delta Cygni A" and "B" derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
Traditionally, Delta Cygni had no proper name. It belonged to the Arabic asterism "al-Fawāris" (), meaning "the Riders" in indigenous Arabic, together with Zeta, Epsilon, and Gamma Cygni, the transverse of the Northern Cross. 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 "Fawaris" for the component Delta Cygni A on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.
In Chinese, (), meaning "Celestial Ford", refers to an asterism consisting of Delta Cygni, Gamma Cygni, 30 Cygni, Alpha Cygni (Deneb) and Nu, Tau, Upsilon, Zeta and Epsilon Cygni. Consequently, the Chinese name for Delta Cygni itself is (, ).
Properties.
The primary, Delta Cygni A, is a blue-white giant star of spectral class B9, with a temperature of 10,500 K. It is nearing the end of its main-sequence life stage with a luminosity 155 times that of the Sun, a radius of 5.13 solar radii, and a mass approximately 2.93 solar masses. Like many hot stars, it spins rapidly, at least 135 kilometers per second at the equator, about 60 times that of the Sun.
The close companion Delta Cygni B is a yellow-white F-type main-sequence star of the sixth magnitude (6.33) with a luminosity about 6 times that of the Sun, and a mass about 1.5 times the Sun's. The two stars orbit each other at an average distance of 157 AU and a period of 780 years.
The much more distant third companion is an orange (class K) twelfth magnitude star, and only two thirds as massive.
The two main stars together appear with a spectral type of A0 IV. As seen from Earth, the entire triple star system of Delta Cygni shines at a combined apparent magnitude of 2.87. Both δ Cygni A and B have been suspected to vary in brightness. δ Cygni A was reported in 1951 as varying between magnitudes 2.85 and 2.89, and δ Cygni B was reported in 1837 to vary between magnitudes 6.3 and 8.5. The variability of the stars has not been confirmed.
Pole Star.
Delta Cygni is a visible star located within 3° of the precessional path traced across the celestial sphere by the Earth's North pole. For at least four centuries around 11,250 AD it will probably be considered a pole star, a title currently held by Polaris which is just 0.5° off of the precessional path.


Lambda Leporis

Lambda Leporis, which is the Latinized form of λ Leporis, is a solitary, blue-white hued star in the southern constellation of Lepus. It is visible to the naked eye with an apparent visual magnitude of +4.29. Based upon an annual parallax shift of 3.83 mas, it is estimated to lie roughly 850 light years from the Sun. Relative to its neighbors, this star has a peculiar velocity of . It is a member of the Orion OB1 association (Ori OB1), and it has been identified as a high-velocity runaway star.
This is a massive, B-type main-sequence star with a corrected stellar classification of B0.5 V. It is an estimated eight million years old and is spinning with a projected rotational velocity of 30 km/s. This star has around 15 times the mass of the Sun and 4.5 times the Sun's radius. It is radiating 15,488 times the Sun's luminosity from its photosphere at an effective temperature of 30,400 K.


Pi Tauri

Pi Tauri (π Tauri) is a solitary, yellow-hued star in the zodiac constellation of Taurus. With an apparent visual magnitude of +4.69, it is bright enough to be visible to the naked eye. Although it appears to lie among the stars of the Hyades cluster, it is not itself a member, being three times farther from Earth than the cluster. The distance to this star, as determined using an annual parallax shift of 7.83 mas as seen from the Earth, is around 420 light years. At that range, the visual magnitude of the star is diminished by an extinction factor of 0.24 due to interstellar dust.
This is an evolved G-type giant star with a stellar classification of , where the suffix notation indicates an underabundance of iron in the spectrum. The measured angular diameter is . At the estimated distance of Pi Tauri, this yields a physical size of about 21 times the radius of the Sun. It possesses nearly four times the mass of the Sun and is radiating 229 times the Sun's luminosity at an effective temperature of 5,086 K.
References.
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Tau4 Eridani

Tau4 Eridani (τ4 Eridani, τ4 Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.
This is an evolved red giant star currently on the asymptotic giant branch with a stellar classification of M3/4 III. It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72 with a periodicity of 23.8 d. The measured angular diameter of Tau4 Eridani is . At its estimated distance, this yields a physical size of about 106 times the radius of the Sun. It shines with 1,537 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,712 K.
This is most likely a binary star system. The companion is a magnitude 9.5 star at an angular separation of 5.7″ along a position angle of 291°, as of 2013.
References.
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Pi Herculis

Pi Herculis (π Her, π Herculis) is a third-magnitude star in the constellation Hercules. As one of the four stars in the Keystone asterism (see yellow quadrangle), it is one of the constellation's more easily recognized. It has an apparent visual magnitude of +3.2, which is visible to the naked eye and makes it one of its brighter members. The Hipparcos satellite mission estimated its distance at roughly 115 parsecs from Earth, or about 377 light years away. The overall reduction in the star's visual magnitude due to extinction from the intervening matter is 0.11.
Properties.
Pi Herculis is a bright giant star with a stellar classification of K3 II. P.C. Keenan and R. E. Pitts (1980) graded it as a spectral type K3 IIab and it is sometimes listed with this alternate classification. The star is enormous compared to the Sun, having a mass that is 4.5 times solar and a radius approximately 60 times depending on which wavelength the star's angular diameter is measured at. Due to limb darkening, all giant and supergiant stars present unique challenges when measuring their photosphere. This orange-hued giant shines with 1,330 times the luminosity of the Sun. It is a low-amplitude photometric variable star showing a typical change of roughly 0.0054 in magnitude over a 24-hour period.
Possible planetary system.
Low-amplitude radial velocity variations with a period of 613 days in the bright giant have suggested the possible presence of a substellar companion. If this is really due to a low-mass object, such a companion would be as small as 0.027 Solar masses (27 times the mass of Jupiter, probably a brown dwarf) and 3 astronomical units away from the bright primary. A substellar companion is only one of several hypotheses to explain the star's behaviour. Most likely the cause of the variation is weak pulsation of the star's atmosphere.
With a luminosity more than 1,000 times that of the Sun, an orbit where a planet could be habitable would be located 37 AU away from Pi Herculis—in Solar System terms, halfway between Neptune and Pluto's orbits. On the other hand, a putative companion would orbit in a scorching region and would be as hot as a planet would at 0.08 AU around a Sun-like star. In any case it's likely that it would soon be swallowed up by the expanding giant.


S2 (star)

S2, also known as S0–2, is a star that is located in the star cluster close to the radio source Sagittarius A* (Sgr A*), orbiting it with a period of 16.0518 years, a semi-major axis of about 970 au, and a pericenter distance of 17 light hours (18 Tm or 120 au) – an orbit with a period only about 30% longer than that of Jupiter around the Sun, but coming no closer than about four times the distance of Neptune from the Sun. The mass when the star first formed is estimated by the European Southern Observatory (ESO) to have been approximately . Based on its spectral type (B0V ~ B3V), it probably has a mass of 10 to 15 solar masses.
Its changing apparent position has been monitored since 1995 by two groups (at UCLA and at the Max Planck Institute for Extraterrestrial Physics) as part of an effort to gather evidence for the existence of a supermassive black hole in the center of the Milky Way galaxy. The accumulating evidence points to Sgr A* as being the site of such a black hole. By 2008, S2 had been observed for one complete orbit. In 2020, partway through its next orbit, the GRAVITY collaboration released an analysis showing full agreement with Schwarzschild geodesics.
A team of astronomers mainly from the Max Planck Institute for Extraterrestrial Physics used observations of S2's orbital dynamics around Sgr A* to measure the distance from the Earth to the galactic center. They determined the distance to be in close agreement with prior determinations of the distance by other methods.
S2 was precisely tracked during its May 2018 close approach to Sgr A*, with results in accord with general relativity predictions.
Nomenclature.
The designation S0–2 was first used in 1998. S0 indicates a star within one arc-second of Sgr A*, indicating the galactic centre, and S0–2 was the second closest star seen at the time of the measurements. The star had been catalogued simply as S2 a year earlier, the second of eleven infrared sources near the galactic centre, numbered approximately anti-clockwise. It is a coincidence that the star is numbered "2" in both lists; other catalogs number it differently.
Orbit.
The highly eccentric orbit of S2 will give astronomers an opportunity to test for various effects predicted by general relativity and even extra-dimensional effects. These effects reached a maximum at closest approach, which occurred in mid-2018. Given a recent estimate of for the mass of the Sgr A* black hole and S2's close approach, this makes S2 the fastest known ballistic orbit, reaching speeds exceeding 5,000 km/s (11,000,000 mph, or the speed of light) and acceleration of about 1.5 m/s2 (almost one-sixth of Earth's surface gravity).
The motion of S2 is also useful for detecting the presence of other objects near to Sgr A*. It is believed that there are thousands of stars, as well as dark stellar remnants (stellar black holes, neutron stars, white dwarfs) distributed in the volume through which S2 moves. These objects will perturb S2's orbit, causing it to deviate gradually from the Keplerian ellipse that characterizes motion around a single point mass. So far, the strongest constraint that can be placed on these remnants is that their total mass comprises less than one percent of the mass of the supermassive black hole.
2018 pericentre passage.
In 2018, S2 made its closest approch to Sgr A*, reaching 7650 km/s or almost 3% of the speed of light, while passing the black hole at a distance of just 120 AU or about 1400 times its Schwarzschild radius. S2 reached its pericenter on May 19, 2018, while its velocity in the line of sight from Earth peaked in April, and later hit its minimum in late August and early September.
Independent analyses by the GRAVITY collaboration (led by Reinhard Genzel) and the KECK/UCLA Galactic Center Group (led by Andrea Ghez) revealed a combined transverse Doppler and gravitational redshift up to 200 km/s/c, in agreement with general relativity predictions.
Additional analyis has revealed a Schwarzschild precession of 12 arcminutes (0.2 degrees) in S2's orbit caused by the close passage, fully consistent with general relativity.
S0–102.
In 2012, a star called S0–102 (or S55) was found to be orbiting even closer to the Milky Way's central supermassive black hole than S0–2 does. At one-sixteenth the brightness of S0–2, S0–102 was not initially recognized because it required many more years of observations to distinguish it from its local infrared background. S0–102 has an orbital period of 11.5 years, even shorter than that of S0–2. Of all the stars orbiting the black hole, only these two have their orbital parameters and trajectories fully known in all three dimensions of space. The discovery of two stars orbiting the central black hole so closely with their orbits fully described is of extreme interest to astronomers, as the pair together will allow much more precise measurements on the nature of gravity and general relativity around the black hole than would be possible from using S0–2 alone.
A still closer star S62 has since been discovered with an orbital period of 9.9 years.


Phi Eridani

φ Eridani (Latinised as Phi Eridani) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.55. The distance to this star, as determined using the parallax method, is around 154 light years.
This is a B-type star with a stellar classification of B8IV-V, suggesting it shows traits of a main sequence star and a subgiant. It is spinning rapidly with a projected rotational velocity of 250 km/s. This rotation is giving the star an oblate shape with an equator that is 17% larger than the polar radius. The estimated angular size is 0.68 milliarcseconds. Since the distance is known, this yields a physical size of around 3.4 times the radius of the Sun. It has 3.55 times the mass of the Sun and radiates 255 times the solar luminosity from its outer atmosphere at an effective temperature of about 13,716 K.
Phi Eridani may form a wide binary star system with a 9th magnitude star at lies an angular separation of 86″. This companion is a G-type main sequence star with a stellar classification of G2V. It may also have a physical association with the naked-eye star Eta Horologii. It is a member of the Tucana-Horologium association, a old group of stars that share a common motion through space.
References.
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DG Canum Venaticorum

DG Canum Venaticorum is a variable binary star system in the northern constellation of Canes Venatici. As of 2009, the pair have an angular separation of 0.20″ along a position angle of 285°, which corresponds to a physical separation of around 3.6 AU. With an apparent visual magnitude of 12.02, the pair are much too faint to be seen with the naked eye. Parallax measurements place the system at a distance of roughly 59 light years from the Earth.
The stellar classification of the primary component is M4.0Ve, indicating it is a red dwarf with emission lines present. It is considered a very young system with an estimated age of just 30 million years and a higher metallicity than the Sun. One of the components is rotating rapidly, with a projected rotational velocity of 50 km/s. At least one of the members of this system is a type of variable known as a flare star, which means it undergoes brief increases in brightness at random intervals. On April 23, 2014, a gamma-ray superflare event was observed by the Swift satellite coming from the position of this system. It may have been perhaps the most luminous such events ever observed coming from a red dwarf star. A secondary radio flare was observed a day later.


6 Canum Venaticorum

6 Canum Venaticorum is a single star in the northern constellation Canes Venatici, located 246 light years from the Sun. It is visible to the naked eye as a faint yellow-hued star with an apparent visual magnitude of +5.01. The star is moving closer to the Earth with a heliocentric radial velocity of −4.2 km/s.
This is an evolved G-type giant star with a stellar classification of G9 III, which means it has exhausted the hydrogen supply at its core and expanded. It is a red clump giant, indicating that it is on the horizontal branch and is generating energy through the helium fusion at its core. Data from the Hipparcos mission provided evidence of microvariability with an amplitude of 0.0056 in magnitude and a frequency of 0.00636 per day, or one cycle every 157 days.
6 Canum Venaticorum is about two billion years old with double the mass of the Sun. It has expanded to 9 times the Sun's radius and is radiating 68 times the Sun's luminosity from its photosphere at an effective temperature of 4,938 K.


63 Cygni

63 Cygni is a single star in the northern constellation of Cygnus, located around 1,030 light years away from Sun. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.56. 63 Cyg is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.
This is an evolved star showing a stellar spectrum with mixed traits between a bright giant and supergiant. It has been chosen as a spectral standard for the class of K4 Ib–IIa.
For reasons that are not yet clear, 63 Cygni is displaying very long period (982 days) and low-amplitude (742 m/s) variations in radial velocity. The star has expanded to 35 times the Sun's radius and is radiating 4,397 times the Sun's luminosity from its photosphere at an effective temperature of 4,204 K.


67 Cancri

67 Cancri is a wide binary star system in the zodiac constellation of Cancer, located 195 light years away from the Sun. It is just visible to the naked eye as a faint, white-hued star with a combined apparent magnitude of 6.07. The binary nature of this system was discovered by James South and John Herschel. As of 2007, the two components have an angular separation of , corresponding to a projected separation of . They are moving further from the Earth with a heliocentric radial velocity of +12 km/s.
The primary, designated component A, is an A-type main-sequence star with a stellar classification of A8 Vn. The 'n' notation indicates "nebulous" lines due to rapid rotation. It is a shell star, with weak shell lines of singly-ionized titanium being detected in the near ultraviolet in 1970. These may have come from a sporadic mass loss event. Uesugi and Fukuda (1970) gave a projected rotational velocity estimate of 105 km/s for the star, although Abt et al. (1997) suggested it could be as high as 205 km/s.
67 Cancri A is about 867 million years old with 1.89 times the mass of the Sun and 1.90 times the Sun's radius. It is radiating 10.5 times the Sun's luminosity from its photosphere at an effective temperature of 7,982 K.


List of stars in Cygnus

This is the list of notable stars in the constellation of Cygnus, sorted by decreasing apparent magnitude.


Chi Centauri

Chi Centauri (χ Cen, χ Centauri) is a star in the constellation Centaurus.
χ Centauri is a blue-white B-type main sequence dwarf with a mean apparent magnitude of +4.36. It is approximately 510 light years from Earth. It is classified as a Beta Cephei type variable star and its brightness varies by 0.02 magnitudes with a period of 50.40 minutes.
This star is a proper motion member of the Upper-Centaurus Lupus sub-group in the
Scorpius-Centaurus OB association,
the nearest such co-moving association of massive stars to the Sun.


Omega Carinae

Omega Carinae, Latinized from ω Carinae, is a star in the constellation Carina. With a declination greater than 70 degrees south of the celestial equator, it is the most southerly of the bright stars of Carina (third-magnitude or brighter), and it is part of a southern asterism known as the Diamond Cross. This star has an apparent visual magnitude of 3.3 and is located at a distance of about from Earth.
Properties.
Omega Carinae has a stellar classification of B8 IIIe, which places it in the category of Be stars, that display emission lines of hydrogen their spectrum. Omega Carinae is a shell star, having a circumstellar disk of gas surrounding its equator. The luminosity class of III indicates it has evolved into a giant star, having exhausted the hydrogen at its core and left the main sequence. The effective temperature of in its outer envelope is what gives this star the blue-white hue that is characteristic of B-type stars.
This star is rotating rapidly with a projected rotational velocity of , which gives a lower limit to the star's azimuthal velocity along the equator. The critical equatorial velocity, at which the star would begin to break up, is . The star's axis of rotation is inclined by an estimated angle of 70.8° to the line of sight from the Earth.
In the next 7500 years, the south Celestial pole will pass close to this star (AD 5800) and then I Carinae.
In culture.
In Chinese, (), meaning "Southern Boat", refers to an asterism consisting of ω Carinae, V337 Carinae, PP Carinae, θ Carinae and β Carinae . Consequently, ω Carinae itself is known as (, .)


NGC 402

NGC 402 is a star located in the constellation of Pisces. It was discovered on October 7, 1874 by Lawrence Parsons.


HIP 57050

HIP 57050 (GJ 1148 / LHS 2443 / G 122-40 / Ross 1003) is a red dwarf 36 light-years from the Sun with a planetary companion HIP 57050 b.
HIP 57050 has a metallicity twice that of the Sun and is among the highest in the immediate solar neighborhood.
Planetary system.
A team led by astronomer Nader Haghighipour reported the discovery of a Saturn-sized planet in the habitable zone of the star in 2010. According to Haghighipour, the detection is important because it "indicates that observational techniques are on the right track for finding habitable low-mass rocky planets similar to Earth."
According to its discoverers, HIP 57050 b provides support for the proposition that planet-bearing M-class stars tend to be metal-rich, a correlation already observed in F, G and K-class stars.
At the expected planetary effective temperature, the atmosphere may contain water clouds, potentially detectable by the Hubble Space Telescope if it could capture a planetary transit.
The planet's discoverers speculated about the possibility of a habitable moon:
Paul Gilster of the Tau Zero Foundation has commented:
Gilster suggested that an Earth-sized moon could exist around the planet if it were captured after forming independently.
A second planet was suspected based on additional radial velocity measurements made at W. M. Keck Observatory, this was confirmed by measurements taken at Calar Alto Observatory.


Gamma Fornacis

The Bayer designation Gamma Fornacis (γ For / γ Fornacis) is shared by two stars, in the constellation Fornax:


60 Serpentis

60 Serpentis, also known as c Serpentis, is a single, orange-hued star in Serpens Cauda, the eastern section of the constellation Serpens. It is faintly visible to the naked eye with an apparent visual magnitude of 5.38. The distance to this star, as estimated from its annual parallax shift of , is approximately 130 light years. It is moving further from the Sun with a heliocentric radial velocity of +28 km/s, having approached as close as some 1.9 million years ago.
This is an evolved K-type giant star with a stellar classification of K0 III, having used up its core hydrogen and expanded. At the age of around 1.26 billion years, it currently belongs to the so-called "red clump", which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star has an estimated 1.8 times the mass of the Sun and 8 times the Sun's radius. It is radiating 35 times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 5,059 K.


Eta Mensae

Eta Mensae, Latinized from η Mensae, is the Bayer designation for a solitary, orange-hued star in the southern constellation of Mensa. This object has an apparent visual magnitude of 5.47, which is sufficiently luminous to be faintly visible to the naked eye. Based upon an annual parallax shift of 4.88 mas as seen from Earth, this star is located roughly 670 light years from the Sun.
This is an evolved K-type giant star with a stellar classification of K4 III. It is radiating 616 times the Sun's luminosity from its photosphere at an effective temperature of 4,055 K. The star displays an infrared excess that suggests the presence of circumstellar dust. Eta Mensae is a probable member of the stream of stars associated with the Hyades cluster.


Omicron Sagittarii

ο Sagittarii, Latinized as Omicron Sagittarii, is a single star in the constellation Sagittarius. It is yellow in hue and visible to the naked eye with an apparent visual magnitude of +3.77. The distance to this star is approximately 142 light years based on parallax. It is drifting further away from the Sun with a radial velocity of +26 km/s, having come to within around a million years ago.
This object is position 0.86 degrees north of the ecliptic, so ο Sagittarii can be occulted by the Moon and very rarely by planets. The last occultation by a planet took place on 24 December 1937, when it was occulted by Mercury. It was almost eclipsed by the sun, which occupies a mean, rounded, half of one degree of the sky, on 5 January. Thus the star can be viewed the whole night, crossing the sky, in early July.
This is an aging giant star with a stellar classification of G9IIIb. It is classified as a red clump giant, suggesting it is on the horizontal branch undergoing core helium fusion. The star is 2.39 billion years old with 1.80 times the mass of the Sun. It has expanded to 12 times the girth of the Sun and is radiating 67 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,744 K.
It has a faint, magnitude 13.8 companion, designated component B and positioned away along a position angle of 252°, as of 2010.


26 Cygni

26 Cygni is a single star in the northern constellation of Cygnus. It has the Bayer designation e Cygni, while "26 Cygni" is the Flamsteed designation. This star is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 5.12. It is located around distant from the Sun, based on parallax measurements. The radial velocity is close to negligible, being measured at −0.3 km/s.
This object is an evolved giant star with a stellar classification of G8 III; a star that has used up its core hydrogen and left the main sequence. It is most likely (88% chance) on the horizontal branch, in which case stellar modelling yields an estimated 2.44 times the mass of the Sun and 22 times the Sun's radius. It is radiating 205 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,700 K.
There is a magnitude 8.94 visual companion at an angular separation of along a position angle of 150°, as of 2014.


List of stars in Equuleus

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


Mu Octantis

The Bayer designation μ Octantis (mu Octantis) is shared by two stars in the constellation Octans:


Mu Eridani

Mu Eridani (μ Eridani) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.00. Based upon an annual parallax shift of 0.00625 arcseconds, it is located roughly 520 light years from the Sun.
In 1910, this was determined to be a single-lined spectroscopic binary star system. The pair orbit each other with a period of 7.38 days and an eccentricity of 0.344, during which they undergo Algol-like eclipses. The primary is a slowly pulsating B-type star with a stellar classification of B5 IV. It has a relatively high rate of rotation with a projected rotational velocity of 130 km/s, which is at least 30% of the star's break-up velocity. The star has about six times the Sun's mass and radius, and it shines with 1,905 times the solar luminosity from its outer atmosphere at an effective temperature of 15,668 K.


Eta2 Coronae Australis

η2 Coronae Australis, Latinized as Eta2 Coronae Australis, is a single star located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.587. Parallax measurements yield a distance estimate of 480 light-years from the Sun, but it is drifting closer with a radial velocity of −23 km/s.
This object has a stellar classification of B9IV, matching a B-type subgiant star. It is 213 million years old with a mass of 3.23 times that of the Sun. The star is radiating 171 times the luminosity of the Sun from its photosphere at an effective temperature of 10,940 K.


Eta Coronae Borealis

Eta Coronae Borealis (η Coronae Borealis, η CrB) is a stellar system that lies approximately 58 light-years away. The primary component is a mid-wide binary, while a brown dwarf component is located at a wide separation.
Components.
Eta Coronae Borealis has been known since the late 18th century to be a moderate-separation binary. The orbit of the two components takes approximately 42 years, which when combined with the distance to the system makes the two stars fairly easily resolvable with a larger telescope. The two stars have similar physical parameters, though the secondary is slightly cooler than the primary and has approximately 90% of the primary's mass. Possible stable planetary orbits in the habitable zone were calculated for the system in 1996.
A brown dwarf companion was detected in 2001. The source 2MASSW J1523226+301456 in the 2MASS working database was identified as having a similar proper motion to the AB binary, and subsequent observations confirmed its relationship to the system. The new component, Eta Coronae Borealis C, was found to have a spectral type of L8. The brown dwarf has a minimum separation of 3600 AU, and considering a cooling age of 1–2.5 gigayears, the brown dwarf has a mass of , or .


HD 47536

HD 47536 is a single star in the southern constellation of Canis Major. It has an orange hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.25. The star is located at a distance of approximately 401 light years from the Sun based on parallax. It is drifting further away with a radial velocity of 80 km/s.
This is an aging, metal-poor giant star with a stellar classification of K1 III. It is about 9.3 billion years old with 94% of the mass of the Sun. Having exhausted the supply of hydrogen at its core, the star cooled and expanded to 23 times the Sun's radius. The star is spinning slowly, taking to complete its sidereal rotation. It is radiating 177 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,384 K. As of 2007, at least one planet is known to orbit this star.
Planetary system.
Setiawan discovered both planets around the star: HD 47536 b in 2003 and HD 47536 c in 2007. However, the existence of this second planet is disputed.


NGC 5053

NGC 5053 is the "New General Catalogue" designation for a globular cluster in the northern constellation of Coma Berenices. It was discovered by German-British astronomer William Herschel on March 14, 1784 and cataloged as VI-7. In his abbreviated notation, he described it as, "an extremely faint cluster of extremely small stars with resolvable nebula 8 or 10′ diameter, verified by a power of 240, beyond doubt". Danish-Irish astronomer John Louis Emil Dreyer reported in 1888 that the cluster appeared, "very faint, pretty large, irregular round shape, growing very gradually brighter at the middle".
This is a metal-poor cluster, meaning the stars have a low abundance of elements other than hydrogen and helium—what astronomers term metallicity. As recently as 1995, it was considered the most metal-poor globular cluster in the Milky Way. The chemical abundances of the stars in NGC 5053 are more similar to those in the dwarf galaxy Sagittarius Dwarf Spheroidal Galaxy than to the Milky Way halo. Along with the kinematics of the globular cluster, this suggests that NGC 5053 may have been stripped from the dwarf galaxy.
There are ten known RR Lyrae variable stars in this cluster with masses ranging from 68% to 78% of the solar mass. Nine of these variables were reported by German astronomer Walter Baade in 1928, and the tenth by American astronomer Helen Sawyer in 1946. The cluster hosts 27 known blue stragglers, of which five are short period SX Phoenicis variable stars.
NGC 5053 is a relatively low mass cluster with a low core concentration factor of 1.32. It sports a stream of tidal debris to the west with a projected length of 1.7 kpc. This stream may have been created through shock-induced processes. The cluster is located less than 1° from Messier 53 and the two have nearly the same distance modulus, which corresponds to a spatial separation of around 2 kpc. There is a tidal bridge joining M53 to NGC 5053, suggesting the pair may have interacted in the past. The cluster is following an orbit through the Milky Way that has a perigalacticon distance of 9 kpc and an orbital eccentricity of 0.84. At present, it is 18.4 kpc from the Galactic Core, with a radial velocity of .


Kepler-89

Kepler-89 is a star with four confirmed planets. Kepler-89 is a possible wide binary star.
Planetary system.
The discovery of four planets orbiting the star was announced October 2012 by analyzing data gathered by Kepler space telescope. Follow-up radial velocity measurements confirmed the existence of Kepler-89d, indicating that Kepler-89d is slightly larger and more massive than Saturn. In October 2013, other three planets were confirmed with Kepler-89c and Kepler-89e getting reasonable mass constraints. Transit-timing variations of the outermost planet suggest that additional planets or minor bodies are present in the system.
In 2012, a partial transit of the second outermost planet by the outermost planet was reported. This was the first time a planet-planet transit in front of the star was detected. This allowed to determine the mutual inclination of the planets d and e to be 1.15°.
Stephen R. Kane did a dynamical analysis of the Kepler-89 system that demonstrated that planets c and d, although close to the 2:1 secular resonance, are not permanently in a 2:1 resonance configuration.


NGC 492

NGC 492, also occasionally referred to as PGC 4976 or GC 280, is a barred spiral galaxy in the constellation Pisces. It is located approximately 590 million light-years from Earth and was discovered on December 6, 1850 by Irish engineer Bindon Blood Stoney. Although John Dreyer, creator of the New General Catalogue, credits the discovery to astronomer William Parsons, 3rd Earl of Rosse, he notes that many of his claimed discoveries were made by one of his assistants. In the case of NGC 492, the discovery was made by Bindon Stoney, who discovered it along with NGC 486, NGC 490 and NGC 500 during his observation of NGC 488 using Lord Rosse's 72" telescope.
The object was initially described by Stoney as "extremely faint, small, round, 25" diameter, low surface brightness, no concentration". The position noted was "on line with a mag 12 star 3.7' NW and a faint pair of mag 14-14.5 stars 2' NW".


Coronet Cluster

The Coronet Cluster, also known as the R CrA cluster after its best-known member, is a small open cluster located about 170 parsecs away in the southern constellation Corona Australis, isolated at the edge of the Gould Belt. The Coronet Cluster is 3.5 times closer to the Earth than the Orion Nebula Cluster. The cluster center is composed of mostly young stars. The variable T Coronae Australis is also a member, only one arc minute from R CrA.


Zeta Circini

Zeta Circini, Latinized from ζ Circini, is the Bayer designation for a star located in the southern constellation of Circinus. With an apparent visual magnitude of 6.08, it is barely visible to the naked eye on a dark night. (According to the Bortle scale, it requires the lighting level of suburban skies or darker to be seen.) The distance to this star, as estimated using an annual parallax shift of 2.56 mas, is around 1,300 light years.
This is a B-type main sequence star with a stellar classification of B2/3 Vn,
where the 'n' suffix indicates broad ("nebulous") absorption lines due to rotation. It is a slowly pulsating B star with a frequency of 0.26877 d−1 and an amplitude of 0.0046 magnitude. The averaged quadratic field strength of the star's longitudinal magnetic field is .
The star is around 32 million years old and is spinning rapidly with a projected rotational velocity of 264 km/s. It has an estimated 5.5 times the mass of the Sun and 3.8 times the Sun's radius. Zeta Circini radiates around 602 times the solar luminosity from its outer atmosphere at an effective temperature of 16,788 K.


Zeta Serpentis

Zeta Serpentis, Latinized from ζ Serpentis, is the Bayer designation for a single, yellow-white hued star in the equatorial constellation of Serpens. It is visible to the naked eye, having an apparent visual magnitude of 4.6. Based upon an annual parallax shift of 42.46 milliarcseconds as measured from the Hipparcos spacecraft, it is located 77 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −50.7 km/s. It will make its closest approach in about 400,000 years when it makes perihelion passage at an estimated distance of .
Around 2.4 billion years old, Zeta Serpentis has a stellar classification of F2 V indicating it is an ordinary F-type main-sequence star. This star has nearly double the radius of the Sun, 1.4 times the Sun's mass, and is radiating 6.3 times the Sun's luminosity from its outer atmosphere at an effective temperature of 6,529 K. It has a relatively high rate of spin, showing a projected rotational velocity of 69 km/s.


Iota2 Scorpii

ι2 Scorpii, Latinised as Iota2 Scorpii, is a single star in tail of the zodiac constellation of Scorpius. It has an apparent visual magnitude of +4.82, and is visible to the naked eye. Because of parallax measurement errors, the distance to this star is only approximately known: it lies around 2,500 light years away from the Sun. It has a visual companion, a magnitude 11.0 star at an angular separation of 31.60 arcseconds along a position angle of 36°, as of 2000.
In the literature, there are two different stellar classifications for this star: A2 Ib and A6 Ib. In either case it is an A-type supergiant star with an estimated age of 30 million years and a mass 8.8 times that of the Sun. It shines with a luminosity 5,798 times the Sun's from an outer atmosphere that has an effective temperature of 6,372 K. As with other stars of its type, ι2 Scorpii varies slightly in brightness, showing an amplitude of 0.05 in magnitude.


Delta Ophiuchi

Delta Ophiuchi (δ Ophiuchi, abbreviated Delta Oph, δ Oph), formally named Yed Prior , is a star in the constellation of Ophiuchus. It forms a naked-eye optical double with Epsilon Ophiuchi (named "Yed Posterior"). The apparent visual magnitude is 2.75, making this a third-magnitude star and the fourth-brightest in the constellation. Parallax measurements from the Hipparcos spacecraft yield a distance estimate of approximately from the Sun (Epsilon Ophiuchi is approximately ).
Nomenclature.
"δ Ophiuchi" (Latinised to "Delta Ophiuchi") is the star's Bayer designation.
It bore the traditional name "Yed Prior". "Yed" derives from the Arabic يد "yad" "hand". "Delta" and "Epsilon Ophiuchi" comprise the left hand of Ophiuchus (the Serpent Bearer) that holds the head of the serpent (Serpens Caput). "Delta" is "Yed Prior" as it leads "Epsilon" across the sky. 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 "Yed Prior" for this star on 5 October 2016 and it is now so included in the List of IAU-approved Star Names.
Delta Ophiuchi was a member of the indigenous Arabic asterism "al-Nasaq al-Yamānī", the "Southern Line" of "al-Nasaqān" the "Two Lines", along with Alpha Serpentis, Delta Serpentis, Epsilon Serpentis, Epsilon Ophiuchi, Zeta Ophiuchi and Gamma Ophiuchi.
In Chinese, (), meaning "Right Wall of Heavenly Market Enclosure", refers to an asterism which represents eleven ancient states in China and which mark the right borderline of the enclosure, consisting of Delta Ophiuchi, Beta Herculis, Gamma Herculis, Kappa Herculis, Gamma Serpentis, Beta Serpentis, Alpha Serpentis, Delta Serpentis, Epsilon Serpentis, Epsilon Ophiuchi and Zeta Ophiuchi. Consequently, the Chinese name for Delta Ophiuchi itself is (, ), representing the state of Liang (梁) (or Leang).
Properties.
Delta Ophiuchi has a stellar classification of M0.5 III, making this a red giant star that has undergone expansion of its outer envelope after exhausting the supply of hydrogen at its core. It is currently on the asymptotic giant branch. The measured angular diameter of this star, after correction for limb darkening, is . At the estimated distance of Delta Ophiuchi, this yields a physical size of about 59 times the radius of the Sun. In spite of its enlarged size, this star has only 1.5 times the mass of the Sun and hence a much lower density. The effective temperature of the outer atmosphere of Delta Ophiuchi is a relatively cool 3,679 K, which is what gives it the orange-red hue of an M-type star.
It is listed as a suspected variable star that may change by 0.03 in visual magnitude. It has a low projected rotational velocity of , which gives a minimum value for the azimuthal velocity along the star's equator. The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is more than double the abundance in the Sun's photosphere.
The star has a high optical linear polarisation that increases from red to blue wavelengths and displays some variability, this has been ascribed to either an asymmetric distribution of dust grains in an envelope expelled from it, or the presence of photometric hot spots.
References.
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Nu Geminorum

Nu Geminorum (ν Gem) is a binary, and possibly a multiple star system in the constellation Gemini. It has an apparent visual magnitude of 4.16, which is bright enough to be visible to the naked eye on a dark night. Based upon an annual parallax shift of 5.99 mas, it is located at a distance of roughly 540 light years from the Sun.
The main components of this potentially multiple star system have an orbital period of 18.75 years and an eccentricity of 0.297. There is much uncertainty in the spectral type, with classifications ranging from a main sequence star to a giant. The spectra indicate the presence of a Be star in the system.
According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", this star was titled as Nucatai.


NGC 7095

NGC 7095 is a barred spiral galaxy located about 115 million light-years away in the constellation of Octans. NGC 7095 was discovered by astronomer John Herschel on September 21, 1837.


W Corvi

W Corvi is an eclipsing binary star system in the constellation Corvus, ranging from apparent magnitude 11.16 to 12.5 over 9 hours. Its period has increased by 1/4 second over a century. It is an unusual system in that its two stars are very close to each other yet have different surface temperatures and hence thermal transfer is not taking place as expected.


Kappa Coronae Borealis

Kappa Coronae Borealis, Latinized from κ Coronae Borealis, is a star approximately 98 light years away in the constellation of Corona Borealis. The apparent magnitude is +4.82 (4.17 trillion times fainter than the Sun) and the absolute magnitude is +2.35 (9.82 times brighter than the Sun). It is an orange K-type subgiant star of spectral type K1IV, meaning it has nearly completely exhausted its hydrogen supply in its core. It is 1.32 times as massive as the Sun yet has brightened to 11.6 times its luminosity. Around 2.5 billion years old, it was formerly an A-type main sequence star.
Dust disk.
In March 2013, it was announced that resolved images of at least one dust disk surrounding Kappa Coronae Borealis were captured, making it the first subgiant to host such circumstellar belt. The disk extends out to 120 AU.
Planetary system.
In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method. In 2012 it was confirmed.
This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa. Given the star's luminosity, the planet is more likely on the zone's inner edge.
The width of the circumstellar belt suggests the presence of a second planetary companion of the star, either within it or between two narrower belts.


Pi Scorpii

Pi Scorpii (π Scorpii, abbreviated Pi Sco, π Sco) is a triple star system in the southern constellation of Scorpius. With a combined apparent magnitude of 2.9, it can be easily seen with the naked eye. Parallax measurements yield an estimated distance of around from the Sun.
It consists of a binary pair, designated Pi Scorpii A, with a more distant third companion, B. A's two components are themselves designated Pi Scorpii Aa (formally named Fang) and Ab.
Nomenclature.
"π Scorpii" (Latinised to "Pi Scorpii") is the system's Bayer designation. The designations of the three constituents as "Pi Scorpii A" and "B" and those of "A's" components - "Pi Scorpii Aa" and "Ab" - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
In Chinese, (), meaning "Room", refers to an asterism consisting of Pi Scorpii, Rho Scorpii, Delta Scorpii, Beta¹ Scorpii and Beta² Scorpii. Consequently, the Chinese name for Pi Scorpii itself is (), "the First Star of Room". 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 "Fang" for the component Pi Scorpii Aa on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
Properties.
The fact that Pi Scorpii had two constituents (A and B) remained unknown until 1899, when it was announced by American astronomer Edward Charles Pickering. Two years later, an orbital period of 1.571 days was found by American astronomer Solon Irving Bailey, but it would not be until 1927 that the precise orbit of this spectroscopic binary was determined by Russian astronomer Otto Struve and American astrophysicist Christian T. Elvey.
The primary, or A, component of this system itself forms an eclipsing binary of the Beta Lyrae type. Both its members are hot, B-type main sequence stars with a blue-white hue. They display an ellipsoidal variation of 0.03 in magnitude. The two stars are rotating rapidly, with projected rotational velocities of 108 and 87 km/s respectively. Their orbital period is 1.57 days and they are separated by an estimated distance of only 15 solar radii along a circular orbit.
The primary is orbited by a smaller, more distant companion (B), which has an apparent magnitude of +12.2. This component is separated from the pair by 50 arcseconds, putting it at least 7000 AU away.
The Pi Scorpii system is a kinematic member of the Upper Scorpius subgroup of the Scorpius-Centaurus Association, a group of thousands of young stars with mean age 11 million years at distance 470 light years (145 parsecs). A recent analysis of the HR diagram position for the primary star Pi Scorpii A estimates its effective temperature to be 25,230 kelvins with a luminosity of 21,900 Suns, consistent with an isochronal age of 12-14 million years and an estimated mass of 12–13 solar masses.


List of stars in Reticulum

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


6 Canis Minoris

6 Canis Minoris is a star in the equatorial constellation of Canis Minor, located around 570 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of +4.55. This object is moving closer to the Earth with a heliocentric radial velocity of −16.3 km/s. Kinematically, it is a member of an outlying group belonging to the Ursa Major flow of the Sirius supercluster.
This is an evolved giant star with a stellar classification of K1 III. It has a mild barium anomaly, which may indicate this is a binary star system with a white dwarf companion. The interferometry-measured angular diameter of the visible component is about , which, at its estimated distance, equates to a physical radius of about 44 times the radius of the Sun. This star has four times the mass of the Sun and is radiating 761 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,370 K.
References.
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NGC 285

NGC 285 is a lenticular galaxy in the constellation Cetus. It was discovered on October 2, 1886 by Francis Leavenworth.


52 Sagittarii

52 Sagittarii is a binary star system in the southern constellation of Sagittarius. It has the Bayer designation h2 Sagittarii, while "52 Sagittarii" is the Flamsteed designation. This system is visible to the naked eye as a faint, blue-white hued point of light with an apparent visual magnitude of 4.59. It is located approximately 190 light years away based on parallax, but is drifting closer with a radial velocity of −19 km/s.
The primary component is a B-type main-sequence star with a stellar classification of B8/9V. Garrison and Gray (1994) assigned it a class of , displaying the calcium K line of a B8 class star, the hydrogen lines of a B9 star, and the helium lines of an A0 star, along with overabundances of strontium and iron. It is around 57 million years old with three times the mass of the Sun and about 2.1 times the Sun's radius. It is radiating 60.5 times the luminosity of the Sun from its photosphere at an effective temperature of 10,592 K. The star is spinning with a projected rotational velocity of 48 km/s.
52 Sagittarii has one companion at an angular separation of . This object is magnitude 9.2 with a spectral class in the K2V-K4V range, and is believed to be the source of X-ray emissions from the system.


NGC 7354

NGC 7354 is a planetary nebula located in the northern circumpolar constellation of Cepheus, at a distance of approximately from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".
This nebula is the result of an aging star casting off its outer atmosphere. Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles. The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning . The outer shell is more circular, and is approximately in diameter. The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.
The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star.


AR Cassiopeiae

AR Cassiopeiae (AR Cas) is a multiple star system in the constellation of Cassiopeia. It is thought to be a septuple star system. It is one of only two known star systems with a multiplicity of 7, the other being Nu Scorpii, with no physical multiple stars of greater multiplicity yet found as of January 2020.
Nomenclature.
AR Cassiopeiae was frequently referred to as IH Cas (or H Cas) in some literature. The origin of the designation "IH Cassiopeiae" is from the 17th century catalogue and constellation map by Johannes Hevelius, which was kept in use due to the lack of a Flamsteed designation or Bayer designation for the star. It was the first star in Cassiopeia that Flamsteed's edition of Hevelius catalogued, thus "1 Hev. Cas" or "1 H. Cas" (similar to Gould designations), which becomes IH Cas through corruption.
Properties.
The primary subsystem, AR Cassiopeiae AB, is a triple. AR Cassiopeiae B is located 0.800″ away from AR Cassiopeiae A. AR Cassiopeiae A itself an Algol-type eclipsing binary with an orbital period of about 6.07 days. Its primary is a B-type main-sequence star, and the secondary, an A-type main-sequence star. The secondary star may be an Am star as well.
Farther out are two other stars, designated AR Cassiopeiae C and D, respectively. They are 76.1″ (or about 1.27′) away from the central system. Their combined spectrum matches that of another B-type main-sequence star. This pair is also designated HD 221237. 67.2″ (1.12′) away from AR Cassiopeiae AB is another pair of stars, F and G, both F-type stars. All four of these stars are known to be common proper motion companions.


Omega Aurigae

Omega Aurigae, Latinized from ω Aurigae, is the Bayer designation for a double star in the northern constellation of Auriga. Its apparent magnitude is 4.95, which is bright enough to be seen with the naked eye. The distance to this system, as determined using parallax measurements, is approximately . The system is a member of the Columba group of co-moving stars.
This is an A-type main sequence star with a stellar classification of A1 V. It is 317 million years old with a high rate of spin, showing a projected rotational velocity of 107 km/s. The star has 2.3 times the mass of the Sun and double the Sun's radius. It is radiating 27 times the Sun's luminosity from its photosphere at an effective temperature of 9,230 K. The object displays an infrared excess, suggesting an orbiting debris disk with a temperature of 20 K at a mean radius of from the host star. It has a magnitude 8.18 companion at an angular separation of 4.99 arcseconds. The system is an X-ray source with a luminosity of .


20 Arietis

20 Arietis is a single star in the northern constellation of Aries. "20 Arietis" is the Flamsteed designation. It has an apparent visual magnitude of 5.79, which is bright enough to be just faintly visible to the naked eye as a yellow-white hued star. The star is located approximately 137 light years away from the Sun based upon parallax. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.188 arc seconds per annum. 20 Arietis is receding from the Earth with a heliocentric radial velocity of +25 km/s.
Gray et al. (2001) gave the stellar classification of 20 Arietis as F6 III-IV, matching an F-type star with spectral traits intermediate between a giant and a subgiant star. Harlan (1969) had found a less-evolved class of F6 IV-V. The star is around two billion years old with an estimated 1.5 times the mass of the Sun and two times the Sun's radius. It is spinning with a projected rotational velocity of 8.0 km/s and has a higher than solar metallicity. The star is radiating 6.6 times the luminosity of the Sun from its photosphere at an effective temperature of around 6,416 K.


Mu Arae c

Mu Arae c, also known as HD 160691 c, formally named Dulcinea (pronounced or ), is an extrasolar planet orbiting the star Mu Arae of the constellation Ara. It was the first 'hot Neptune' or 'mega-Earth' to be discovered.
None of the four planets orbiting Mu Arae are directly visible from Earth using currently available tools. All four were found using the radial velocity method of extrasolar planet detection.
Discovery.
The planet's discovery was announced on August 25, 2004. At the time, its minimum mass was reported at just 14 times that of Earth, although later work established a value of 10.5 Earth masses. It orbits very close to Mu Arae, completing one revolution every 9.6 days. The discovery was made with the aid of the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph, at the European Southern Observatory's La Silla Observatory in Chile. The data that revealed the presence of this planet was gathered on 8 nights of observations in June 2004.
Name.
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Dulcinea for this planet. The winning name was submitted by the Planetario de Pamplona, Spain. Dulcinea was the love-interest of the lead character of the novel "El Ingenioso Hidalgo Don Quixote de la Mancha".
Characteristics.
Assuming its true mass is comparable to those of Neptune and Gliese 436 b, 14 Earth masses is theoretically the maximum size for a terrestrial planet. A rocky planet this size could certainly have formed, since Mu Arae has a higher metallicity than our Sun. Also, it is thought to have formed well inside the system's "snow line" at 3.2 AU. However, various models of the system's formation have since converged that the planet attracted large amounts of volatiles before its star had cleared out the ice, and that it now has a core of only 6 Earth masses. Its core is likely enveloped in so much hot-ice and gas that the planet would behave more like Neptune.
Mu Arae c is too far from its sun to be subject to coronal mass ejections. There is disagreement as to whether it is and has always been a hot Neptune in mass (Lammer), or if it could have developed from a gas giant, losing most of its mass on the way (Baraffe).
If an eroded gas giant, the sun would have boiled the planet from a larger protoplanet, of 20 Earth masses up to half Jupiter's mass. If the latter, its current radius could be as high as 0.6 Jupiter.
The planet must be hot because of its proximity to its star. The discoverers chose for it an albedo of 0.35, lighter than albedos chosen to calculate the temperatures of hot Jupiters such as tau Boötis b. This was perhaps due to the discoverers' assumption that the planet would be a silicate super-terrestrial with neither clouds nor a deep Rayleigh-scattering atmosphere. If so the surface temperature would be about 900 K.


Gamma Centauri

Gamma Centauri (γ Cen, γ Centauri) is a star in the southern constellation Centaurus. It has the proper name Muhlifain, not to be confused with Muliphein, which is γ Canis Majoris; both names derive from the same Arabic root.
It is a binary star system about from Earth. The combined apparent visual magnitude of the pair is +2.17; individually they are third magnitude stars. The stellar classification of the pair is A1IV+, suggesting they are A-type subgiant stars in the process of becoming giants. Individually, their stellar classifications are sometimes listed as A0III, which would mean they have already become giants.
In 2000, the pair had an angular separation of 1.217 arcseconds with a position angle of 351.9°. Their positions have been observed since 1897, which is long enough to estimate an orbital period of 84.5 years and a semimajor axis of 0.93 arcseconds. At the distance of this system, this is equivalent to a linear distance of about 93 Astronomical Units. The star Tau Centauri is relatively close to Gamma Centauri, with an estimated separation of .
Etymology.
In Chinese astronomy, (), meaning "Arsenal", refers to an asterism consisting of γ Centauri, ζ Centauri, η Centauri, θ Centauri, 2 Centauri, HD 117440, ξ1 Centauri, τ Centauri, D Centauri and σ Centauri. Consequently, the Chinese name for γ Centauri itself is (, .)
The people of Aranda and Luritja tribe around Hermannsburg, Central Australia named "Iritjinga", "The Eagle-hawk", a quadrangular arrangement comprising this star, δ Cen (Ma Wei), δ Cru (Imai) and γ Cru (Gacrux).


25 Scorpii

25 Scorpii (abbreviated to 25 Sco) is a star in the zodiac constellation of Scorpius, located about 920 light years away from the Sun. Its apparent magnitude is 6.71, so its apparent brightness is at the limit of human eyesight and can only be seen under excellent conditions, according to the Bortle scale. The object is moving closer to the Earth with a heliocentric radial velocity of −1.3 km/s. It is a proposed member of the Scorpius-Centaurus association.
This is an evolved bright giant with a spectral type of K0 II. It is about two times more massive and over twelve times wider than the Sun. The star is radiating 135 times the Sun's luminosity from its photosphere at an effective temperature of about 4,700 K.


HD 28375

HD 28375 is a single star in the equatorial constellation of Taurus, near the southern constellation border with Eridanus. It was previously known by the Flamsteed designation 44 Eridani, although the name has fallen out of use because constellations were redrawn, placing the star out of Eridanus and into Taurus. The star is blue-white in hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.53. The distance to this star is approximately 480 light-years based on parallax. It is drifting further away with a radial velocity of 18 km/s, after having come to within an estimated some 3.7 million years ago.
Cowley (1972) and later Bragança et al. (2012) found a stellar classification of B3V for this object, matching a B-type main-sequence star. Houk and Swift assigned it a class of B5 III/IV, suggesting it is a more evolved star that is entering the giant stage. It has five times the mass of the Sun and is around three million years old, with a projected rotational velocity of just 13 km/s. The star is radiating 127 times the luminosity of the Sun from its photosphere at an effective temperature of about 13,000 K.
An infrared excess has been detected, indicating the presence of a circumstellar disk. The dust has a temperature of about 119 K and is orbiting from the star.


Tau Orionis

Tau Orionis (τ Ori, τ Orionis) is a solitary star in the constellation Orion. If an imaginary line is drawn north-west between the stars Rigel and Mintaka, Tau Orionis can be found roughly one-sixth of the way to Mintaka. It is visible to the naked eye with an apparent visual magnitude of 3.58. Based upon an annual parallax shift of 6.6 mas, it is located around 490 light years from the Sun.
This is a B-type giant star with a stellar classification of B5III5 III. It has around 5.4 times the radius of the Sun and 6.2 times the Sun's mass. The star shines with 933 times the solar luminosity from its outer atmosphere at an effective temperature of 10,829 K. it is around 63 million years old, with a peculiar velocity through space of 16.9 km/s.
Tau Orionis has three visual companions: magnitude 11.0 component B at an angular separation of 33.30″ along a position angle of 251°; magnitude 10.9 component C lying some 3.80″ from component B; and magnitude 10.9 component D at 36.0″ from τ Ori along a position angle of 51°, all as of 2011.
Proper names.
According to Richard H. Allen, this star, along with β Eri, λ Eri and ψ Eri were Al Kursiyy al Jauzah, "the Chair (or "Footstool") of the Central One". However, per the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "Al Kursiyy al Jauzah" were the title for just three stars: β Eri as "Cursa", ψ Eri as "Al Kursiyy al Jauzah I" and λ Eri as "Al Kursiyy al Jauzah II", excluding this star.
In Chinese, (), meaning "Jade Well", refers to an asterism consisting of τ Orionis, β Eridani, λ Eridani and ψ Eridani. Consequently, the Chinese name for τ Orionis itself is (, .). From this Chinese title, the name Yuh Tsing is derived.


CG 4

CG 4, commonly referred to as God's Hand, is a star-forming region located in the Puppis constellation, about from Earth. It is one of several objects referred to as "cometary globules", because its shape is similar to that of a comet. It has a dense head formed of gas and dust, which is around in diameter, and an elongated faint tail around in length.
, and the nearby cometary globules, generally point away from the Vela Supernova Remnant, located at the center of the Gum Nebula.
Discovery.
In 1976, photographs from the UK Schmidt Telescope—operated by the Australian Astronomical Observatory—showed several objects resembling comets, located in the Gum Nebula, an emission nebula of the constellation. Due to their particular shape, these objects came to be known as cometary globules. Each globule has a dense, dark, ruptured head and a very long tail, with the latter pointing away from the Vela Supernova Remnant. As a part of the ESO Cosmic Gems program, the European Southern Observatory released an image of in January 2015 showing the head of the nebula.
Structure.
The head of cometary globule resembles a comet with a dusty cavernous mouth, as photographed by the European Southern Observatory's Very Large Telescope in 2015. Composed of relatively dense, dark matter, it is an opaque structure that is being illuminated by the glow of a nearby star. An obscure red glow limbing the globule is possibly caused by emission from ionized hydrogen. The mouth of the globule appears to be ready to consume the edge-on spiral galaxy . In reality, the galaxy is over a hundred million light-years further away from the globule.


QS Aquilae

QS Aquilae is a triple star system consisting of an eclipsing binary in a 2.5 day orbit around which a third star orbits in 77 years. It is located in the constellation Aquila and is barely visible to the naked eye.


Kepler-90g

Kepler-90g (also known by its Kepler Object of Interest designation "KOI-351.02") is a super-puff exoplanet orbiting the early G-type main sequence star Kepler-90, one of eight planets around this star discovered using NASA's Kepler space telescope. It is located about from Earth, in the constellation Draco. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. It orbits its parent star about every 210.5 days at a distance of 0.71 astronomical units.
Kepler-90g's orbital period changes by 25.7 hours between two consecutive transits, caused by gravitational perturbations from other planets in the system. Additionally, changes in the depth and duration of transit events led to an exomoon being hypothesized to orbit this planet. However, this candidate moon was later found to be a false positive.
A 2020 analysis of transit-timing variations of Kepler-90g and h found a best-fit mass of for planet g. Given a transit-derived radius of , Kepler-90g was found to have an extremely low density of , unusually inflated for its mass and insolation. Several possible explanations for its apparently low density include a puffy planet with a dusty atmosphere or a smaller planet surrounded by a tilted wide ring system (albeit the latter option is less likely due to the lack of evidence for rings in transit data).


NGC 3608

NGC 3608 is an elliptical galaxy located in the constellation Leo. It was discovered by William Herschel on March 14, 1784.


56 Aquilae

56 Aquilae is a single star in the equatorial constellation of Aquila. "56 Aquilae" is its Flamsteed designation. Its apparent visual magnitude is 5.79, meaning it is barely visible to the naked eye as a dim, orange-hued point of light, under ideal viewing conditions. The star is located at a distance of around 580 light years away from the Sun, based on parallax. It is moving closer to the Earth with a heliocentric radial velocity of −50 km/s, and is predicted to come as near as in around 3.3 million years.
This is an aging giant star with a stellar classification of K5 III, having exhausted the supply of hydrogen at its core and expanded to 42 times the Sun's radius. It is radiating 391 times the luminosity of the Sun from its photosphere at an effective temperature of 3,972 K. 56 Aquilae is a double star, but it does not appear to be a binary star system. It is one of the double stars profiled in Admiral William Henry Smyth's 1864 work, "Sidereal Chromatics".