Upsilon2 Cassiopeiae

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υ2 Cassiopeiae
Upsilon2 cassiopeiae diagram.jpg
Map of the Bayer-designated stars in Cassiopeia. Upsilon2 Cassiopeiae is circled.
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cassiopeia
Right ascension 00h 56m 39.90413s [1]
Declination +59° 10 51.8006 [1]
Apparent magnitude  (V)+4.62 [2]
Characteristics
Evolutionary stage horizontal branch [3]
Spectral type G8 IIIb Fe−0.5 [4]
U−B color index +0.68 [2]
B−V color index +0.96 [2]
Astrometry
Radial velocity (Rv)−47.73±0.12 [5]  km/s
Proper motion (μ)RA: −92.085 [1]   mas/yr
Dec.: −45.079 [1]   mas/yr
Parallax (π)17.2875 ± 0.1880 [1]   mas
Distance 189 ± 2  ly
(57.8 ± 0.6  pc)
Absolute magnitude  (MV)+0.62 [6]
Details [5]
Mass 1.44±0.16  M
Radius 10.44+0.24
−0.50
[1]   R
Luminosity 55.3±0.7 [1]   L
Surface gravity (log g)2.75±0.19  cgs
Temperature 4,937±14  K
Metallicity [Fe/H]−0.35±0.03  dex
Rotational velocity (v sin i)0.54±0.38 km/s
Age 2.20±0.62  Gyr
Other designations
Castula, υ2 Cas, 28 Cassiopeiae, BD+58° 138, HD  5395, HIP  4422, HR  265, SAO  21855
Database references
SIMBAD data

Upsilon2 Cassiopeiae, Latinised from υ2 Cassiopeiae, is a solitary star in the constellation of Cassiopeia, a few degrees to the south of Gamma Cassiopeiae. It has the proper name Castula /ˈkæstjʊlə/ , which has been officially adopted by the IAU. [7] The star has a yellow hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.62. [2] Based upon parallax measurements, it is located at a distance of approximately 189  light years from the Sun. [1] The star is drifting closer with a radial velocity of −48 km/s. [5]

This is an aging giant star with a stellar classification of G8 IIIb Fe−0.5, [4] where the suffix notation indicates a mild underabundance of iron in the spectrum. With the supply of core hydrogen exhausted, this star has cooled and expanded off the main sequence – at present it has 10 [1] times the girth of the Sun. It is a red clump giant, which means it is on the horizontal branch undergoing core helium fusion. [3]

Upsilon2 Cassiopeiae is a barium star, showing an excess of the element barium in its spectrum. This can occur from mass transfer from a more-evolved companion star that later became a white dwarf, although no companion has been detected. [6] It is 2.2 billion years old with 1.44 times the mass of the Sun. [5] The star is radiating 55 [1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,937 K. [5]

Nomenclature

υ2 Cassiopeiae is the star's Bayer designation. In 2016, the IAU organized a Working Group on Star Names (WGSN) [8] to catalog and standardize proper names for stars. The WGSN approved the name Castula for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names. [7]

Related Research Articles

Upsilon Andromedae Star in Andromeda constellation

Upsilon Andromedae is a binary star located approximately 44 light-years from Earth in the constellation of Andromeda. The system consists of an F-type main-sequence star and a smaller red dwarf.

Delta Arietis

Delta Arietis, officially named Botein, is a star in the northern constellation of Aries, 1.8 degrees north of the ecliptic. The apparent visual magnitude is 4.35, so it is visible to the naked eye. It has an annual parallax shift of 19.22 mas; corresponding to a distance of about 170 ly (52 pc) from the Sun.

Alpha Cassiopeiae Star in the constellation Cassiopeia

Alpha Cassiopeiae, also named Schedar, is a second magnitude star in the constellation of Cassiopeia. Though listed as the "alpha star" by Johann Bayer, α Cas's visual brightness closely matches the 'beta' (β) star in the constellation and it may appear marginally brighter or dimmer, depending on which passband is used. However, recent calculations from NASA's WISE telescope confirm that α Cas is the brightest in Cassiopeia, with an apparent magnitude of 2.240. Its absolute magnitude is 18 times greater than β Cas, and it is located over four times farther away from the Sun.

Alpha Crateris

Alpha Crateris, officially named Alkes, is a star in the constellation of Crater. It is a cool giant star about 43.2 parsecs (141 ly) away.

Upsilon Serpentis, Latinized from υ Serpentis, is a star in the Serpens Caput section of the constellation Serpens. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.70. It is a member of the Hyades group, a stream of stars that share a similar trajectory to the Hyades cluster.

14 Andromedae, abbreviated 14 And, also named Veritate, is a single, orange-hued giant star situated approximately 247 light-years away in the northern constellation of Andromeda. It is dimly visible to the naked eye with an apparent visual magnitude of 5.22. The star is moving closer to the Earth with a heliocentric radial velocity of −60 km/s. In 2008 an extrasolar planet was discovered to be orbiting the star.

Omicron Piscium

Omicron Piscium is a binary star in the constellation of Pisces. It is visible to the naked eye, having an apparent visual magnitude of 4.27. Based upon an annual parallax shift of 11.67 mas as seen from the Earth, the system is located roughly 280 light-years from the Sun. It is positioned near the ecliptic, so is subject to occultation by the Moon. It is a member of the thin disk population of the Milky Way.

Upsilon<sup>2</sup> Eridani Star in the constellation of Eridanus

Upsilon² Eridani, officially named Theemin, is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.8. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately 66 parsecs from the Sun.

Pi¹ Cygni is a binary star in the northern constellation of Cygnus. It is visible to the naked eye, having a combined apparent visual magnitude of 4.66. The distance to this system can be roughly gauged by its annual parallax shift of 1.89 mas, which yields a separation of around 1,700 light years from the Sun, give or take a hundred light years.

Eta Eridani

Eta Eridani, officially named Azha, is a giant star in the constellation of Eridanus. Based on parallax measurements taken during the Hipparcos mission, it is approximately 137 light-years from the Sun.

Alpha<sup>2</sup> Capricorni Star in the constellation Capricornus

Alpha2 Capricorni, or Algedi, is a triple star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +3.57. It is separated from the fainter α¹ Capricorni by 0.11° of the sky, a gap just resolvable with the naked eye, similar to Mizar and Alcor. Based on parallax shift as refined from orbits around the sun of the Gaia spacecraft at earth's Lagrange point 2, the star is 101 to 103 light years from the solar system.

Upsilon<sup>1</sup> Cassiopeiae Star in the constellation Cassiopeia

Upsilon1 Cassiopeiae is an astrometric binary star system in the northern constellation of Cassiopeia. It is visible to the naked eye with an apparent visual magnitude of 4.82. Based upon an annual parallax shift of 9.93 mas as seen from Earth, this system is located about 330 light years from the Sun.

Tau Cassiopeiae Star in the constellation Cassiopeia

Tau Cassiopeiae is a solitary, orange hued star in the northern constellation of Cassiopeia. It is bright enough to be seen with the naked eye, having an apparent visual magnitude of +4.86. Based upon an annual parallax shift of 18.75 mas as seen from Earth, this system is located about 174 light years from the Sun.

Upsilon Ceti Star in the constellation Cetus.

Upsilon Ceti, Latinized from υ Ceti, is a solitary star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.95. Based upon an annual parallax shift of 11.14 mas, it is located about 293 light years from the Sun.

Upsilon¹ Hydrae, also named Zhang, is a yellow-hued star in the constellation of Hydra. It is visible to the naked eye, having an apparent visual magnitude of 4.12. Based upon an annual parallax shift of 12.36 mas as seen from Earth, it is located about 264 light-years from the Sun. The star is moving closer to the Sun with a radial velocity of −14.34 km/s. In 2005 it was announced that it had a substellar companion.

Eta Sagittae

Eta Sagittae (η Sagittae) is solitary star in the northern constellation of Sagitta. It is faintly visible to the naked eye, having an apparent visual magnitude of +5.09. Based upon an annual parallax shift of 20.34 mas, it is approximately 160 light years distant from the Sun. There is a 61.1% chance that it is a member of the Hyades-Pleiades stream of stars that share a common motion through space.

Chi Piscium Star in the constellation Pisces

Chi Piscium (χ Piscium) is a solitary, orange-hued star in the zodiac constellation of Pisces. It can be seen with the naked eye, having an apparent visual magnitude of +4.64. Based upon an annual parallax shift of 8.50 mas as seen from Earth, it is located about 384 light years from the Sun.

Upsilon³ Eridani, officially named Beemim, is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.96 The distance to this star, based upon an annual parallax shift of 11.01 mas, is around 296 light-years.

Upsilon Pegasi Star in the constellation Pegasus.

Upsilon Pegasi, Latinised from υ Pegasi, is a star within the great square in the northern constellation of Pegasus. It has the proper name Alkarab. This object has a yellow-white hue and is faintly visible to the naked eye with an apparent magnitude of 4.40. It is located at a distance of approximately 170 light-years from the Sun based on parallax, but is drifting closer with a radial velocity of −8.6 km/s. The star is moving through the Galaxy at a speed of 50.6 km/s relative to the Sun. Its projected Galactic orbit carries it between 18,600 and 26,300 light-years from the center of the Galaxy.

Alruba

Alruba, a name derived from Arabic for "the foal", is a suspected astrometric binary star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76. Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years from the Sun. The system is drifting closer with a radial velocity of −2 km/s.

References

  1. 1 2 3 4 5 6 7 8 9 10 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133 (4): 475, Bibcode:1966MNRAS.133..475A, doi: 10.1093/mnras/133.4.475 .
  3. 1 2 Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society , 408 (2): 1225–1232, arXiv: 1006.3857 , Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x, S2CID   44228180.
  4. 1 2 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  5. 1 2 3 4 5 Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv: 1410.6422 , Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID   53666931.
  6. 1 2 Bergeat, J.; Knapik, A. (May 1997), "The barium stars in the Hertzsprung-Russel diagram.", Astronomy and Astrophysics, 321: L9, Bibcode:1997A&A...321L...9B.
  7. 1 2 Naming Stars, IAU.org, retrieved 16 December 2017
  8. IAU Working Group on Star Names (WGSN), IAU.org, retrieved 22 May 2016