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61 Virginis

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61 Virginis (abbreviated 61 Vir) is the Flamsteed designation of a G-type main-sequence star (G7V) slightly less massive than the Sun (which has a hotter G2V spectral type), located 27.8 light-years (8.5 parsecs) away in the constellation of Virgo. The composition of this star is nearly identical to the Sun.

61 Virginis

61 Vir as seen with a 12.5" telescope with a field of view of 45.1 arcminutes
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 13h 18m 24.31399s[1]
Declination −18° 18′ 40.2977″[1]
Apparent magnitude (V) 4.74
Characteristics
Spectral type G7V[2]
Apparent magnitude (B) 5.45
Apparent magnitude (J) 3.334
Apparent magnitude (H) 2.974
Apparent magnitude (K) 2.956
U−B color index 0.26
B−V color index 0.71
V−R color index 0.37
R−I color index 0.33
Astrometry
Radial velocity (Rv)−7.86±0.13[1] km/s
Proper motion (μ) RA: −1,070.202 mas/yr[1]
Dec.: −1,063.849 mas/yr[1]
Parallax (π)117.1726 ± 0.1456 mas[1]
Distance27.84 ± 0.03 ly
(8.53 ± 0.01 pc)
Absolute magnitude (MV)5.07[3]
Details
Mass0.93[4] M☉
Radius0.9867±0.0048[4] R☉
Luminosity0.8222±0.0033[4] L☉
Surface gravity (log g)4.5[5] cgs
Temperature5538±13[4] K
Metallicity [Fe/H]−0.02[5] dex
Rotation29 days[6]
Rotational velocity (v sin i)3.9 ± 0.9[7] km/s
Age6.1–6.6[8] Gyr
Other designations
BD-17°3813, FK5 1345, GCTP 3039.00, GJ 506, HD 115617, HIP 64924, HR 5019, LHS 349, LTT 5111, SAO 157844.
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata

61 Virginis (G7V) is the first well-established main-sequence star very similar to the Sun with a potential super-Earth,[9] though it was preceded by CoRoT-7 (a borderline orange dwarf).

Description

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61 Virginis is a fifth-magnitude G-type main-sequence star with a stellar classification of G7 V.[2] It is faint but visible to the naked eye south and east of the bright star Spica in the zodiac constellation of Virgo. The designation 61 Virginis originated in the star catalogue of English astronomer John Flamsteed, as part of his Historia Coelestis Britannica. An 1835 account of Flamsteed's work by English astronomer Francis Baily noted that the star showed a proper motion.[10] This made the star of interest for parallax studies, and by 1950 a mean annual value of 0.006″ was obtained.[11] The present day result, obtained with data from the Gaia satellite, gives a parallax of 117.17 mas,[12] which corresponds to a physical separation of 27.8 light-years from the Sun.

This star is similar in physical properties to the Sun, with around 95%[9] of the Sun's mass, 98%[9] of the radius, and 85%[13] of the Luminosity. The abundance of elements is also similar to the Sun, with the star having an estimated 95%[5] of the Sun's proportion of elements other than hydrogen and helium. It is older than the Sun at around 6.1–6.6[8] billion years of age, and is spinning with a leisurely projected rotational velocity of 4[7] km/s at the equator. On average, there is only a low level of activity in the stellar chromosphere[5] and it is a candidate for being in a Maunder minimum state.[14] But the star was suspected as variable in 1988,[15] and a burst of activity was observed between Julian days [24]54800 (29 November 2008) and 55220 (23 January 2010).[6]

The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7 km/s. 61 Vir is orbiting through the Milky Way galaxy at a distance of 6.9 kpc from the core, with an eccentricity of 0.15. It is believed to be a member of the disk population.[13][8]

Planetary system

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On 14 December 2009, scientists announced the discovery of three exoplanets with minimum masses between 5 and 25 times that of Earth orbiting 61 Virginis, using the radial velocity method at the Keck and Anglo-Australian Observatories.[9][16] The three planets all orbit very near the star; when compared to the orbits of the planets in the Solar System, all three would orbit inside that of Venus. The two outer planets likely resemble Uranus and Neptune, while the innermost planet may be a mini-Neptune or a rocky super-Earth.

The outermost of these three planets, 61 Virginis d (also designated HD 115617 d), was initially not detected in the HARPS data as of 2012 until a reanalysis of the data was done in 2023.[17] A 2021 study listed it as a false positive,[18]: 75  but in 2023 two published studies further confirmed it based on an additional 10 years of radial velocity data, though with a smaller minimum mass.[19]: 23 [17]: 13 

Debris disk

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The ecliptic of the 61 Virginis system, as inferred from its dust disc, is inclined to the Solar System at 77°. The star itself is probably inclined at 72°.[6]

A survey with the Spitzer Space Telescope revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk in orbit around the star. This disk was resolved at 70 μm. It was then thought to correspond to an inner radius of 96 AU from the star and outer radius at 195 AU; it is now constrained 30 to over 100 AU.[6] The total mass of the disk is 5 × 10−5 the mass of the Earth.[6][20]

On 27 November 2012, the European Space Agency declared that the debris disc (like that of the Gliese 581 planetary system) has "at least 10 times" as many comets as does the Solar System.[citation needed]

Limits on additional planets

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In 1988, a study surmised that 61 Virginis was a "possible variable", but no companions were then found.[15] A subsequent study, over eleven years, also failed to find any companion up to the mass of Jupiter and out to 3 AU.[21]

As of 2012, "planets more massive than Saturn orbiting within 6 AU" were ruled out.[6] The ESA has further ruled out Saturn-mass planets beyond that.[22]

Additional data is needed to confirm the possibility of more sub-Saturn planets between 0.5 and 30 AU from the star.[6] An Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible. As the three 61 Virginis planets are more massive and closer-in than the Sun's terrestrial planets, such an Earth-mass planet would also serve as the system's Mars analogue.

The 61 Virginis planetary system[9][6][19][17]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥5.98+0.3
−0.29 M🜨 		0.050201±0.000005 4.21498±0.00014 0.033±0.029 — —
c ≥17.94+0.73
−0.7 M🜨 		0.2175±0.0001 38.079±0.008 0.026±0.023 — —
d ≥10.82+1.23
−1.03 M🜨 		0.476±0.001 123.2±0.2 0.15±0.11 — —
Debris disk 30–>100 AU — —
  •  
    Diagram of the 61 Virginis system

View from 61 Virginis

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The Sun is barely visible from the system as a small star close to the much brighter Sirius. Arcturus (magnitude −1.01) is the brightest star of the night sky.[23]

See also

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References

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  1. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b Gray, R. O.; et al. (October 2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I.", The Astronomical Journal, 126 (4): 2048–2059, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID 119417105
  3. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
  4. ^ a b c d von Braun, Kaspar; et al. (2014). "Stellar diameters and temperatures - V. 11 newly characterized exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 438 (3): 2413–2425. arXiv:1312.1792. Bibcode:2014MNRAS.438.2413V. doi:10.1093/mnras/stt2360.
  5. ^ a b c d Perrin, M.-N.; Cayrel de Strobel, G.; Dennefeld, M. (February 1988), "High S/N detailed spectral analysis of four G and K dwarfs within 10 PC of the sun", Astronomy and Astrophysics, 191 (2): 237–247, Bibcode:1988A&A...191..237P
  6. ^ a b c d e f g h Wyatt, M. C.; et al. (2012). "Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems". MNRAS. 424 (2): 1206–1223. arXiv:1206.2370. Bibcode:2012MNRAS.424.1206W. doi:10.1111/j.1365-2966.2012.21298.x. S2CID 54056835.
  7. ^ a b Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672.
  8. ^ a b c Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. S2CID 27151456.
  9. ^ a b c d e Vogt, Steven; Wittenmyer; Paul Butler; Simon O'Toole; Henry; Rivera; Stefano Meschiari; Gregory Laughlin; Tinney (2010). "A Super-Earth and two Neptunes Orbiting the Nearby Sun-like star 61 Virginis". The Astrophysical Journal. 708 (2): 1366–1375. arXiv:0912.2599. Bibcode:2010ApJ...708.1366V. doi:10.1088/0004-637X/708/2/1366. S2CID 1979253.
  10. ^ Baily, Francis, ed. (1835). An Account of the Revd. John Flamsteed, the First Astronomer- Royal. By order of the Lords Commissioners of the Admiralty. p. 588.
  11. ^ Staff (1950). "Stars, Parallax of: Stellar parallaxes determined photographically at the Cape Observatory (seventeenth list)". Monthly Notices of the Royal Astronomical Society. 110 (4): 405–412. Bibcode:1950MNRAS.110..405.. doi:10.1093/mnras/110.4.405.
  12. ^ van Leeuwen, F. (November 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
  13. ^ a b Porto de Mello, Gustavo; del Peloso, Eduardo F.; Ghezzi, Luan (April 2006). "Astrobiologically Interesting Stars Within 10 Parsecs of the Sun". Astrobiology. 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. S2CID 119459291.
  14. ^ Lubin, Dan; Tytler, David; Kirkman, David (March 2012). "Frequency of Maunder Minimum Events in Solar-type Stars Inferred from Activity and Metallicity Observations". The Astrophysical Journal Letters. 747 (2): L32. Bibcode:2012ApJ...747L..32L. doi:10.1088/2041-8205/747/2/L32.
  15. ^ a b Campbell, Bruce; et al. (1988). "A search for substellar companions to solar-type stars". Astrophysical Journal. 331: 902–921. Bibcode:1988ApJ...331..902C. doi:10.1086/166608., pages 904, 906, and 919
  16. ^ Tim Stephens (2009-12-14). "New planet discoveries suggest low-mass planets are common around nearby stars". UCSC News. UC Santa Cruz. Archived from the original on 23 December 2009. Retrieved 2009-12-14.
  17. ^ a b c Cretignier, M.; Dumusque, X.; Aigrain, S.; Pepe, F. (18 August 2023). "YARARA V2: Reaching sub m/s precision over a decade using PCA on line-by-line RVs". Astronomy & Astrophysics. EDP Sciences. arXiv:2308.11812. doi:10.1051/0004-6361/202347232. ISSN 0004-6361.
  18. ^ Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; Isaacson, Howard T.; Howard, Andrew W.; Dedrick, Cayla M.; Sherstyuk, Ilya A.; Blunt, Sarah C.; Petigura, Erik A.; Knutson, Heather A.; Behmard, Aida; Chontos, Ashley; Crepp, Justin R.; Crossfield, Ian J. M.; Dalba, Paul A.; Fischer, Debra A.; Henry, Gregory W.; Kane, Stephen R.; Kosiarek, Molly; Marcy, Geoffrey W.; Rubenzahl, Ryan A.; Weiss, Lauren M.; Wright, Jason T. (2021). "The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades". The Astrophysical Journal Supplement Series. 255 (1): 8. arXiv:2105.11583. Bibcode:2021ApJS..255....8R. doi:10.3847/1538-4365/abe23c. S2CID 235186973.
  19. ^ a b Laliotis, Katherine; Burt, Jennifer A.; et al. (April 2023). "Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions". The Astronomical Journal. 165 (4): 176. arXiv:2302.10310. Bibcode:2023AJ....165..176L. doi:10.3847/1538-3881/acc067.
  20. ^ Tanner, Angelle; et al. (October 2009). "Survey of Nearby FGK Stars at 160 μm with Spitzer". The Astrophysical Journal. 704 (1): 109–116. arXiv:0908.0049. Bibcode:2009ApJ...704..109T. doi:10.1088/0004-637X/704/1/109. S2CID 108609.
  21. ^ Cumming, Andrew; Marcy, Geoffrey W.; Butler, R. Paul (1999). "The Lick Planet Search: Detectability and Mass Thresholds". Astrophysical Journal. 526 (2): 890–915. arXiv:astro-ph/9906466. Bibcode:1999ApJ...526..890C. doi:10.1086/308020. S2CID 12560512.
  22. ^ ESA Herschel (27 November 2012). "Do missing Jupiters mean massive comet belts?".
  23. ^ "The Chronicles of Local Space – 61 Virginis". Archived from the original on 2016-03-03. Retrieved 2012-08-07.
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