70 Virginis

70 Virginis is a binary[10] star located 58[1] light years from the Sun in the equatorial constellation of Virgo, near the northern constellation border with Coma Berenices. 70 Virginis is its Flamsteed designation. The star is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of +4.97.[2] It is drifting further away with a heliocentric radial velocity of +4.4 km/s[2] and has a high proper motion, traversing the celestial sphere at the rate of 0.621 arc seconds per annum.[11]

70 Virginis

70 Virginis system as rendered in Celestia
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension 13h 28m 25.80819s[1]
Declination +13° 46′ 43.6430″[1]
Apparent magnitude (V) +4.97[2]
Characteristics
Spectral type G4 V-IV[3]
U−B color index 0.26
B−V color index 0.714±0.007[2]
V−R color index 0.39
R−I color index 0.36
Variable type none
Astrometry
Radial velocity (Rv)4.44±0.13[2] km/s
Proper motion (μ) RA: −235.562[1] mas/yr
Dec.: −576.283[1] mas/yr
Parallax (π)55.8347 ± 0.1730 mas[4]
Distance58.4 ± 0.2 ly
(17.91 ± 0.06 pc)
Absolute magnitude (MV)+3.70±0.01[5]
Details
Mass1.12[6] M☉
Radius1.9±0.1[7] R☉
Luminosity2.92±0.03[8] L☉
Surface gravity (log g)3.58 cgs
Temperature5,406±64[8] K
Metallicity [Fe/H]−0.06[8] dex
Rotational velocity (v sin i)4.83[9] km/s
Age7.9[8] Gyr
Other designations
70 Vir, BD+14°2621, GJ 512.1, HD 117176, HIP 65721, HR 5072, SAO 100582, WDS 13284+1347A
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata
Extrasolar Planets
Encyclopaedia		data

This object has a stellar classification of G4 V-IV,[3] being rather unusually bright for a main sequence star of its type and thus may be just starting to evolve into the subgiant phase. It is an estimated 7.9[8] billion years old and is spinning with a projected rotational velocity of 4.8 km/s.[9] The star has 1.12[6] times the mass of the Sun and 1.9[7] times the Sun's radius. It is radiating 2.92[8] times the luminosity of the Sun from its photosphere at an effective temperature of 5,406 K.[8] The metallicity – a term astronomers use to describe the abundance of elements heavier than helium – is near solar.[8]

In 2011, a star was discovered 2.86 arcseconds away from the primary, and is likely associated with 70 Virginis. Based on its properties, it has a spectral type later than M5V, and has a mass of about 8% that of the Sun.[10] There is also an L-type brown dwarf 42.7 arcseconds away from the primary, but it is unclear whether this is bound to the system.[10]

In 1996, 70 Virginis was discovered to have an extrasolar planet in orbit around it.[12] There is also an orbiting dusty disc with an average temperature of 153 K located at a mean distance of 3.4 AU from the star.[13]

Planetary system

The discovery of the planet around 70 Virginis was announced on January 17, 1996 at the meeting of the American Astronomical Society in San Antonio, Texas. The planet was detected using radial velocity measurements taken with the C. Donald Shane telescope at Lick Observatory. It has an orbital period of 117 days, an eccentricity of 0.4, and a mass at least 7.4 times that of Jupiter.[14][12]

The 70 Virginis planetary system[15]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >7.40±0.02 MJ 0.481±0.003 116.6926±0.0014 0.399±0.002 — —
Dust disc >3.4 AU — —

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. 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.
  3. Strassmeier, K. G.; Ilyin, I.; Weber, M. (2018). "PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards". Astronomy & Astrophysics. 612: A45. arXiv:1712.06967. Bibcode:2018A&A...612A..45S. doi:10.1051/0004-6361/201731633. S2CID 119244142.
  4. 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. S2CID 18759600. Vizier catalog entry
  5. Holmberg; et al. (2009). "HD 117176". Geneva-Copenhagen Survey of Solar neighbourhood III. Retrieved 2010-02-02.
  6. Shaya, Ed J.; Olling, Rob P. (January 2011), "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue", The Astrophysical Journal Supplement, 192 (1): 2, arXiv:1007.0425, Bibcode:2011ApJS..192....2S, doi:10.1088/0067-0049/192/1/2, S2CID 119226823
  7. Gerard T. van Belle & Kaspar von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085. S2CID 18370219. (web Preprint)
  8. Boyajian, Tabetha S.; et al. (July 2013), "Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations", The Astrophysical Journal, 771 (1): 31, arXiv:1306.2974, Bibcode:2013ApJ...771...40B, doi:10.1088/0004-637X/771/1/40, S2CID 14911430, 40. See Table 3.
  9. Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725, S2CID 43455849.
  10. Fontanive, C.; Rice, K.; Bonavita, M.; Lopez, E.; Muzic, K.; Biller, B. (2019). "A high binary fraction for the most massive close-in giant planets and brown dwarf desert members". Monthly Notices of the Royal Astronomical Society. 485 (4): 4967–4996. arXiv:1903.02332. Bibcode:2019MNRAS.485.4967F. doi:10.1093/mnras/stz671.
  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, S2CID 2603568.
  12. Marcy, Geoffrey W.; Butler, R. Paul (1996). "A Planetary Companion to 70 Virginis". The Astrophysical Journal Letters. 464 (1): L147–L151. Bibcode:1996ApJ...464L.147M. doi:10.1086/310096. S2CID 9528214.
  13. Trilling, D. E.; et al. (2008). "Debris Disks around Sun-like Stars". The Astrophysical Journal. 674 (2): 1086–1105. arXiv:0710.5498. Bibcode:2008ApJ...674.1086T. doi:10.1086/525514. S2CID 54940779.
  14. Sanders, Robert (January 17, 1996). "Discovery of two new planets -- the second and third within the last three months -- proves they aren't rare in our galaxy" (Press release). University of California, Berkeley. Retrieved December 22, 2017.
  15. Kane, Stephen R.; et al. (2015). "A Comprehensive Characterization of the 70 Virginis Planetary System". The Astrophysical Journal. 806 (1). 60. arXiv:1504.04066. Bibcode:2015ApJ...806...60K. doi:10.1088/0004-637X/806/1/60. S2CID 42414832.
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