Upsilon2 Cassiopeiae

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]

For other star systems with this Bayer designation, see υ Cassiopeiae
υ2 Cassiopeiae

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
Distance189 ± 2 ly
(57.8 ± 0.6 pc)
Absolute magnitude (MV)+0.62[6]
Details[5]
Mass1.44±0.16 M☉
Radius10.44+0.24
−0.50[1] R☉
Luminosity55.3±0.7[1] L☉
Surface gravity (log g)2.75±0.19 cgs
Temperature4,937±14 K
Metallicity [Fe/H]−0.35±0.03 dex
Rotational velocity (v sin i)0.54±0.38 km/s
Age2.20±0.62 Gyr
Other designations
Castula, υ2 Cas, 28 Cassiopeiae, BD+58° 138, HD 5395, HIP 4422, HR 265, SAO 21855
Database references
SIMBADdata

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]

gollark: You can parse this using a list of English prefixes and some algorithm for splitting it up.
gollark: ++apioform ↓ this is you
gollark: Yes
gollark: ++apioform ↓ bandicoots
gollark: ++apioform ↓ <@160279332454006795>

References
  1. 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. Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133: 475, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
  3. 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.
  4. 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. 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.
  6. 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. Naming Stars, IAU.org, retrieved 16 December 2017
  8. IAU Working Group on Star Names (WGSN), IAU.org, retrieved 22 May 2016
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.