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 about 27.9 light-years away in the constellation of Virgo. The composition of this star is nearly identical to the Sun.
Star in the constellation Virgo
61 Virginis
61 Vir as seen with a 12.5" telescope with a field of view of 45.1 arcminutes
61 Virginis (G7V) is the first well-established main-sequence star very similar to the Sun with a potential Super-Earth,[10] though it was preceded by COROT-7 (a borderline orange dwarf).
Description
61 Virginis is a fifth-magnitude G-type main-sequence star with a stellar classification of G7V.[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.[11] This made the star of interest for parallax studies, and by 1950 a mean annual value of 0.006″ was obtained.[12] The present day result, obtained with data from the Hipparcos satellite, gives a parallax of 116.89mas,[1] which corresponds to a physical separation of 27.9light years from the Sun.
This star is similar in physical properties to the Sun, with around 95%[10] of the Sun's mass, 98%[10] 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%[7] of the Sun's proportion of elements other than hydrogen and helium. It is older than the Sun at around 6.1–6.6[9] billion years of age, and is spinning with a leisurely projected rotational velocity of 4[8] km/s at the equator. On average, there is only a low level of activity in the stellar chromosphere[7] 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).[16]
The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7km/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][9]
Planetary system
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°.[16]
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.[17]
On 14 December 2009, scientists announced the discovery of three planets with masses between 5 and 25 times that of Earth orbiting 61 Virginis.[10][18] 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 outermost of these three, d, has not yet been confirmed in the HARPS data.[16]
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.[16] The total mass of the disk is 5 × 10−5 the mass of the Earth.[16][19]
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]
As of 2012, "planets more massive than Saturn orbiting within 6 AU" were ruled out.[16] The ESA has further ruled out Saturn-mass planets beyond that.[20]
Additional data is needed to confirm the possibility of more sub-Saturn planets between 0.5 (really, 0.3) and 30 AU from the star.[16] An Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.
A 2021 study found 61 Virginis d to be a false positive.[21]
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.[25]
Gray, R. O.; etal. (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, S2CID119417105
Nidever, David L.; etal. (August 2002), "Radial Velocities for 889 Late-Type Stars", The Astrophysical Journal Supplement Series, 141 (2): 503–522, arXiv:astro-ph/0112477, Bibcode:2002ApJS..141..503N, doi:10.1086/340570, S2CID51814894
Holmberg, J.; etal. (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, S2CID118577511.
von Braun, Kaspar; etal. (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.
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
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, S2CID53666672.
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. S2CID27151456.
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. S2CID1979253.
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: 8. arXiv:2105.11583. doi:10.3847/1538-4365/abe23c. S2CID235186973.
m sin i = 5.1. This true-mass value assumes about 75 degree inclination per Wyatt.
m sin i = 18.2. This true-mass value assumes about 75 degree inclination per Wyatt.
m sin i = 22.9 ± 2.6. This true-mass value assumes about 75 degree inclination per Wyatt.
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