61 Virginis
Encyclopedia
61 Virginis is a G5V class star slightly less massive than the Sun
(G2V), located about 27.8 light-years away in the constellation
of Virgo
. The composition of this star is nearly identical to the Sun and there is only a low level of activity in the stellar chromosphere
.
This star is rotating once every 29 days at the equator. 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 disk star with an estimated age of more than six billion years.
61 Virginis (G5V) is the first well established main sequence
yellow dwarf star very similar to the Sun with a potential Super-Earth
, though COROT-7 (a borderline orange dwarf) is arguably the first.
s, with an orbit slightly smaller and a year slightly less than that of the Earth.
A survey of this star 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, corresponding to an inner radius of 96 AU
from the star. The outer radius is estimated as 195 AU and the total mass of the disk is the mass of the Earth.
On 14 December 2009, scientists announced the discovery of three planets
with masses between 5 and 25 times that of Earth orbiting around 61 Virginis. The three planets all orbit very near the star; when compared to the orbits of the planets in our solar system, all three would orbit inside the orbit of Venus
. Additional data is needed to confirm the possibility of a fourth planet, although an Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
(G2V), located about 27.8 light-years away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Virgo
Virgo (constellation)
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is . Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky...
. The composition of this star is nearly identical to the Sun and there is only a low level of activity in the stellar chromosphere
Chromosphere
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep....
.
This star is rotating once every 29 days at the equator. 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
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy at a distance of 6.9 kpc from the core, with an eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
of 0.15. It is believed to be a disk star with an estimated age of more than six billion years.
61 Virginis (G5V) is the first well established main sequence
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
yellow dwarf star very similar to the Sun with a potential Super-Earth
Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...
, though COROT-7 (a borderline orange dwarf) is arguably the first.
Planetary system
There was some evidence that it may have a jovian planet, but it seemed not to have a nearby massive companion. A subsequent study also failed to find the large substellar companion (with 20 to 80 times the mass of Jupiter) or a Jupiter-class planet, so it was a good candidate for possessing a family of terrestrial planetTerrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...
s, with an orbit slightly smaller and a year slightly less than that of the Earth.
A survey of this star with the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk
Debris disk
A debris disk is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a...
in orbit around the star. This disk was resolved at 70 μm, corresponding to an inner radius of 96 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
from the star. The outer radius is estimated as 195 AU and the total mass of the disk is the mass of the Earth.
On 14 December 2009, scientists announced the discovery of three planets
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
with masses between 5 and 25 times that of Earth orbiting around 61 Virginis. The three planets all orbit very near the star; when compared to the orbits of the planets in our solar system, all three would orbit inside the orbit of Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
. Additional data is needed to confirm the possibility of a fourth planet, although an Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.
See also
- GJ 1214GJ 1214GJ 1214 is a dim M4.5 red dwarf in the constellation Ophiuchus with an apparent magnitude of 14.7. It is located at a distance of approximately 40 light years from Earth. It is about one-fifth as large as the Sun with a surface temperature estimated to be...
- HD 1461HD 1461HD 1461 is a G0V class star slightly more massive than the Sun , located about 76 light-years away in the constellation of Cetus.As of December 2009, HD 1461 is now the largest main sequence star with a possible Super-Earth around it....
- List of extrasolar planets
- List of stars in Virgo