ET Virginis

ET Virginis is a single,[11] red-hued star in the equatorial constellation of Virgo. It can be viewed with the naked eye, having an apparent visual magnitude of 4.91.[2] Based upon an annual parallax shift of 5.9 mas,[1] it is located 560 light years away. It is moving further from the Earth with a heliocentric radial velocity of +18.6 km/s,[5] having come within 177 ly of the Sun around 6.3 million years ago.[6]

ET Vir Pulsation Cycles[12]
Period (Days) 22.623.836.437.639.848.8259.1
Amplitude (mag.) 0.0210.0230.0180.0270.0210.0190.032
ET Virginis
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 14h 10m 50.48706s[1]
Declination −16° 18′ 07.3105″[1]
Apparent magnitude (V) 4.910[2]
Characteristics
Spectral type M2 IIIa[3]
U−B color index +1.72[2]
Variable type SRB[4]
Astrometry
Radial velocity (Rv)+18.58±0.56[5] km/s
Proper motion (μ) RA: +3.277[1] mas/yr
Dec.: −10.804[1] mas/yr
Parallax (π)5.8655 ± 0.2552[1] mas
Distance560 ± 20 ly
(170 ± 7 pc)
Absolute magnitude (MV)−0.81[6]
Details
Radius88[7] R☉
Temperature3,672[2] K
Metallicity [Fe/H]−0.21±0.06[8] dex
Rotational velocity (v sin i)2.3±0.9[9] km/s
Other designations
ET Vir, BD−15° 3817, HD 123934, HIP 69269, HR 5301, SAO 158401[10]
Database references
SIMBADdata

This is an evolved red giant star with a stellar classification of M2 IIIa.[3] It is a semiregular variable star of subtype SRB with a magnitude that ranges from a high of 4.80 down to 5.00.[4] The measured angular diameter of this star, after correcting for limb darkening, is 4.79±0.34 mas.[13] At its estimated distance, this yields a physical size of 88 times the radius of the Sun.[7]

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. Soubiran, C.; et al. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
  3. 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.
  4. Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  8. Gáspár, András; et al. (August 2016), "The Correlation between Metallicity and Debris Disk Mass", The Astrophysical Journal, 826 (2): 14, arXiv:1604.07403, Bibcode:2016ApJ...826..171G, doi:10.3847/0004-637X/826/2/171, S2CID 119241004, 171.
  9. Zamanov, R. K.; et al. (October 2008), "Rotational velocities of the giants in symbiotic stars - III. Evidence of fast rotation in S-type symbiotics", Monthly Notices of the Royal Astronomical Society, 390 (1): 377–382, arXiv:0807.3817, Bibcode:2008MNRAS.390..377Z, doi:10.1111/j.1365-2966.2008.13751.x, S2CID 118697261.
  10. "HD 123934". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 August 2018.
  11. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  12. Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.
  13. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
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