Astronomy:Omega Virginis

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Short description: Star in the constellation Virgo
ω Virginis
Location of ω Virginis (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Virgo
Right ascension  11h 38m 27.60727s[1]
Declination +08° 08′ 03.4663″[1]
Apparent magnitude (V) 5.23 - 5.50[2][3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M4 III[5]
U−B color index +1.63[6]
B−V color index +1.60[6]
Variable type LB[2] or SR[3]
Astrometry
Radial velocity (Rv)+5.13±0.52[7] km/s
Proper motion (μ) RA: −3.89[1] mas/yr
Dec.: +5.30[1] mas/yr
Parallax (π)6.56 ± 0.36[1] mas
Distance500 ± 30 ly
(152 ± 8 pc)
Absolute magnitude (MV)+0.2[8]
Details
Mass1.55[9] M☉
Radius138 ± 17[10][lower-alpha 1] R☉
Luminosity2,300±500[10] L☉
Surface gravity (log g)0.8[8] cgs
Temperature3,400±100[10] K
Metallicity [Fe/H]−0.08[8] dex
Other designations
ω Vir, 1 Virginis, BD+08°2532, FK5 2932, HD 101153, HIP 56779, HR 4483, SAO 118965[11]
Database references
SIMBADdata

Omega Virginis (ω Vir, ω Virginis) is a solitary[5] star in the zodiac constellation Virgo. It has an apparent visual magnitude of +5.2,[5] which is bright enough to be faintly visible to the naked eye. Based upon an annual stellar parallax shift of 6.56 milliarcseconds,[1] it is located about 500 light years from the Sun.

A light curve for Omega Virginis, plotted from Hipparcos data[12]

This is a red giant star with a stellar classification of M4 III.[5] It is thought to be on the asymptotic giant branch (AGB), with shells of hydrogen and helium around a carbon-oxygen core.[4] After evolving away from the main sequence it has expanded to around 140 times the solar radius,[lower-alpha 1] and now shines with 2,300 times the luminosity of the Sun. The effective temperature of the photosphere is 3,400 K.[10]

Omega Virginis is a semiregular variable with a brightness that varies over an amplitude of 0.28 with periods of 30 and 275 days.[13] The General Catalogue of Variable Stars gives the magnitude range as 5.23 to 5.50.[2] It was formally declared a variable star in 1972 following a 1969 study showing small-amplitude variations.[14][15]

Notes

  1. ↑ 1.0 1.1 Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:(5,7723,400)4⋅2,300=138 R⊙.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 2.2 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  3. ↑ 3.0 3.1 Omega Vir, AAVSO, https://www.aavso.org/vsx/index.php?view=detail.top&oid=38127, retrieved 2022-01-08 
  4. ↑ 4.0 4.1 Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal 104 (1): 275–313, doi:10.1086/116239, Bibcode: 1992AJ....104..275E 
  5. ↑ 5.0 5.1 5.2 5.3 Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  6. ↑ 6.0 6.1 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M. 
  7. ↑ Famaey, B. et al. (2009), "Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations", Astronomy and Astrophysics 498 (2): 627–640, doi:10.1051/0004-6361/200810698, Bibcode: 2009A&A...498..627F 
  8. ↑ 8.0 8.1 8.2 Smith, V.V.; Lambert, D.L. (1986), "The chemical composition of red giants. II - Helium burning and the s-process in the MS and S stars", Astrophysical Journal 311: 843–863, doi:10.1086/164823, Bibcode: 1986ApJ...311..843S 
  9. ↑ Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (20 December 2021), "Stellar and substellar companions from Gaia EDR3", Astronomy & Astrophysics 657: A7, doi:10.1051/0004-6361/202142146, ISSN 0004-6361, Bibcode: 2022A&A...657A...7K 
  10. ↑ 10.0 10.1 10.2 10.3 Alonso-Hernández, J.; Sánchez Contreras, C.; Sahai, R.; Sanz-Forcada, J. (2026-04-13), "The dusty envelopes of asymptotic giant branch stars with ultraviolet excesses", Astronomy & Astrophysics, doi:10.1051/0004-6361/202659537, ISSN 0004-6361 
  11. ↑ "* ome Vir". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+ome+Vir. 
  12. ↑ /ftp/cats/more/HIP/cdroms/cats, Strasbourg astronomical Data Center, https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats, retrieved 15 October 2022 
  13. ↑ Glass, I. S.; Van Leeuwen, F. (2007), "Semiregular variables in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society 378 (4): 1543–1549, doi:10.1111/j.1365-2966.2007.11903.x, Bibcode: 2007MNRAS.378.1543G. 
  14. ↑ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1973), "59th Name-List of Variable Stars", Information Bulletin on Variable Stars 834: 1, Bibcode: 1973IBVS..834....1K 
  15. ↑ Eggen, Olin J. (1969), "Light Variations of Small Amplitude in the Red Giants of the Disc Population", Information Bulletin on Variable Stars 355 (355, #1. (IBVS Homepage)): 1, Bibcode: 1969IBVS..355....1E 



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