16 Virginis

16 Virginis is a single[9] star in the zodiac constellation of Virgo, located about 308[1] light years from the Sun. It has the Bayer designation c Virginis; 16 Virginis is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.96.[2] This is an IAU radial velocity standard star;[10] it is moving further from the Earth with a heliocentric radial velocity of +37 km/s.[4] The star has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.301″ per year.[11]

16 Virginis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Virgo
Right ascension  12h 20m 20.98133s[1]
Declination +03° 18′ 45.2604″[1]
Apparent magnitude (V) 4.96[2]
Characteristics
Spectral type K0.5 IIIb Fe−0.5[3]
B−V color index 1.16[2]
Astrometry
Radial velocity (Rv)+36.66±0.17[4] km/s
Proper motion (μ) RA: −292.95[1] mas/yr
Dec.: −63.58[1] mas/yr
Parallax (π)10.59 ± 0.25[1] mas
Distance308 ± 7 ly
(94 ± 2 pc)
Absolute magnitude (MV)0.26[5]
Details
Mass1.62[2] M☉
Radius18[6] R☉
Luminosity131.8[2] L☉
Surface gravity (log g)2.20[7] cgs
Temperature4,423±32[2] K
Metallicity [Fe/H]−0.33[7] dex
Age3.22[2] Gyr
Other designations
c Vir, 16 Vir, NSV 5558, BD+04°2604, HD 107328, HIP 60172, HR 4695, SAO 119341[8]
Database references
SIMBADdata

In Chinese astronomy, 16 Virginis is called 謁者, Pinyin: Yèzhě, meaning Usher to the Court, because this star is marking itself and stand alone in Usher to the Court asterism, Supreme Palace enclosure mansion (see : Chinese constellation).[12]

This is an evolved K-type giant star with a stellar classification of K0.5 IIIb Fe−0.5,[3] where the suffix notation denotes a mild underabundance of iron in the spectrum. It is a red clump giant, which indicates is on the horizontal branch generating energy via helium fusion at its core.[13] The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 1.74±0.02 mas,[14] which, at its estimated distance, equates to a physical radius of about 18 times the radius of the Sun.[6] It is about three[2] billion years old with 1.62[2] times the mass of the Sun and is radiating 132[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,423 K.[2]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  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. 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.
  5. Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440.
  6. 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:
  7. Jofré, P.; et al. (2014), "Gaia FGK benchmark stars: Metallicity", Astronomy and Astrophysics, 564: A133, arXiv:1309.1099, Bibcode:2014A&A...564A.133J, doi:10.1051/0004-6361/201322440.
  8. "c Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-02-10.
  9. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  10. Batten, A. H.; Crampton, D.; Fletcher, J. M.; Morbey, C. L. (1971), "Wavelength Standards for the Measurement of Radial Velocities", Publications of the Dominion Astrophysical Observatory, 13: 441, Bibcode:1971PDAO...13..441B.
  11. Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854.
  12. Ridpath, Ian, "Virgo the Virgin", Startales.
  13. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.
  14. Richichi, A.; Percheron, I.; Khristoforova, M. (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.

Horizontal-branch stars

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