61 Virginis

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61 Virginis
61 Vir as seen with a 12.5" telescope with a field of view of 45.1 arcminutes.jpg

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]
Distance 27.84 ± 0.03  ly
(8.53 ± 0.01  pc)
Absolute magnitude  (MV)5.07 [3]
Details
Mass 0.93 [4]   M
Radius 0.9867±0.0048 [4]   R
Luminosity 0.8222±0.0033 [4]   L
Surface gravity (log g)4.5 [5]   cgs
Temperature 5538±13 [4]   K
Metallicity [Fe/H]−0.02 [5]   dex
Rotation 29 days [6]
Rotational velocity (v sin i)3.9 ± 0.9 [7]  km/s
Age 6.1–6.6 [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
SIMBAD data
Exoplanet Archive data
ARICNS data

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.

Contents

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

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

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

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

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±0.0000054.21498±0.000140.033±0.029
c ≥17.94+0.73
−0.7
  M🜨
0.2175±0.000138.079±0.0080.026±0.023
d≥10.82+1.23
−1.03
  M🜨
0.476±0.001123.2±0.20.15±0.11
Debris disk30>100 AU

View from 61 Virginis

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

Related Research Articles

<span class="mw-page-title-main">70 Virginis</span> Star in the constellation Virgo

70 Virginis is a binary star located 59 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. It is drifting further away with a heliocentric radial velocity of +4.4 km/s and has a high proper motion, traversing the celestial sphere at the rate of 0.621 arc seconds per annum.

<span class="mw-page-title-main">82 G. Eridani</span> Star in the constellation Eridanus

82 G. Eridani is a star 19.7 light-years away from Earth in the constellation Eridanus. It is a main-sequence star with a stellar classification of G6 V, and it hosts a system of at least three planets and a dust disk.

107 Piscium is a single star in the constellation of Pisces. 107 Piscium is the star's Flamsteed designation. John Flamsteed numbered the stars of Pisces from 1 to 113, publishing his Catalogus Britannicus in 1725. He accidentally numbered 107 Piscium twice, as he also allocated it the designation of 2 Arietis. This star is faintly visible to the naked eye with an apparent visual magnitude that has been measured varying between 5.14 and 5.26. However, that finding of variation was not confirmed by subsequent observations and is most likely spurious data. It is located at a distance of about 24.8 light years away from the Sun. 107 Piscium is drifting closer to the Sun with a radial velocity of −33.6, and is predicted to come as close as 15.4 light-years in around 135,800 years.

Xi Boötis, Latinised from ξ Boötis, is a binary star system located at a distance of 22 light-years away from Earth. It is the nearest visible star in the constellation Boötes. The brighter, primary component of the pair has a visual magnitude of 4.70, making it visible to the naked eye.

HD 169830 is a star in the southern constellation of Sagittarius. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.90. The star is located at a distance of 120 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −17.3 km/s, and is predicted to come as close as 20.7 ly (6.4 pc) in 2.08 million years. HD 169830 is known to be orbited by two large Jupiter-like exoplanets.

<span class="mw-page-title-main">Gamma Virginis</span> Star in the constellation Virgo

Gamma Virginis, officially named Porrima, is a binary star system in the constellation of Virgo. It consists of two almost identical main sequence stars at a distance of about 38 light-years.

<span class="mw-page-title-main">Beta Virginis</span> Star in the constellation Virgo

Beta Virginis, a name Latinised from β Virginis, is a star in the equatorial constellation of Virgo. It has the proper name Zavijava, and, despite its designation 'beta', is the fifth-brightest star in Virgo with an apparent visual magnitude of 3.604. The distance to this star is 35.7 light-years based on parallax, and it is drifting further away with a radial velocity of +4.1 km/s. It is 0.69 of a degree north of the ecliptic, so it can be occulted by the Moon and (rarely) by planets. The next planetary occultation of Beta Virginis will take place on 09 november 2210, by Venus.

<span class="mw-page-title-main">Iota Virginis</span> Binary star system in the constellation Virgo

Iota Virginis is a binary star in the constellation of Virgo. Its apparent magnitude is 4.08. Based on its parallax, it is assumed to be relatively nearby, at 71.8 light-years.

<span class="mw-page-title-main">Mu Virginis</span> F-type main sequence star in the constellation Virgo

Mu Virginis, Latinized from μ Virginis, is a star in the zodiac constellation of Virgo. It was listed in the Calendarium of Al Achsasi al Mouakket as rijl al-‘awwā’, Arabic رجل العواء, meaning "The foot of the barking (dog)". With an apparent visual magnitude of 3.88, it is bright enough to be seen with the naked eye. The position of the star near the celestial equator means it is visible from most of the Earth. Based upon parallax measurements, Mu Virginis is located some 59.6 light-years from the Sun.

<span class="mw-page-title-main">Omicron Virginis</span> Star in the constellation Virgo

Omicron Virginis is a star in the zodiac constellation of Virgo. It is visible to the naked eye with an apparent visual magnitude of +4.12. Based upon parallax measurements, it is about 163 light years from the Sun.

<span class="mw-page-title-main">Tau Virginis</span> Star in the constellation Virgo

Tau Virginis is a single star in the zodiac constellation Virgo. With an apparent visual magnitude of 4.28, it is faintly visible to the naked eye. The distance to Tau Virginis, based upon parallax measurements, is approximately 225 light years with a margin of error of ±3 light years.

<span class="mw-page-title-main">Chi Virginis</span> Star in the constellation Virgo

Chi Virginis is a double star in the constellation Virgo. Based upon parallax measurements, it is approximately 315 light-years from Earth. It has an apparent visual magnitude of 4.65, which is bright enough to be seen with the unaided eye under suitable viewing conditions.

HD 222582 is a multiple star system in the equatorial constellation of Aquarius. It is invisible to the naked eye with an apparent visual magnitude of 7.7, but can be viewed with binoculars or a small telescope. The system is located at a distance of 137 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +12 km/s. It is located close enough to the ecliptic that it is subject to lunar occultations.

<span class="mw-page-title-main">61 Virginis b</span> Hot super-Earth orbiting 61 Virginis

61 Virginis b is an extrasolar planet, orbiting the 5th magnitude G-type star 61 Virginis, in Virgo. This planet has a minimum mass of 5.1 times that of Earth and is an example of a super-Earth planet. It orbits very close to the star, at a distance of 0.050201 AU with an eccentricity of 0.12. This planet was discovered on 14 December 2009 using the radial velocity method taken at Keck and Anglo-Australian Observatories.

Gliese 179 is a small red dwarf star with an exoplanetary companion in the equatorial constellation of Orion. It is much too faint to be visible to the naked eye with an apparent visual magnitude of 11.94. The system is located at a distance of 40.5 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of –9 km/s. It is a high proper motion star, traversing the celestial sphere at an angular rate of 0.370″·yr−1.

<span class="mw-page-title-main">HD 114613</span> Star in the constellation Centaurus

HD 114613 is a fifth magnitude yellow subgiant that lies 66.7 light-years away in the constellation of Centaurus. The star may be host to a long-period giant planet.

16 Virginis is a single star in the zodiac constellation of Virgo, located about 308 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. This is an IAU radial velocity standard star; it is moving further from the Earth with a heliocentric radial velocity of +37 km/s. The star has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.301″ per year.

59 Virginis is a G-type main-sequence star, located in constellation Virgo at approximately 57 light-years from Earth.

<span class="mw-page-title-main">RT Virginis</span> Star in the constellation Virgo

RT Virginis is a variable star in the equatorial constellation of Virgo, abbreviated RT Vir. It ranges in brightness from an apparent visual magnitude of 7.7 down to 9.7, which is too faint to be visible to the naked eye. Based on parallax measurements made with the VLBI, the distance to this star is approximately 740 light years. It is receding from the Sun with a radial velocity of 17 km/s.

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