61 Virginis

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Star
61 Virginis
61 Virginis as seen through a 12.5 inch telescope with a field of view of 45.1 arc minutes
61 Virginis as seen through a 12.5 inch telescope with a field of view of 45.1 arc minutes
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Virgin
Right ascension 13 h 18 m 24.31 s
declination −18 ° 18 ′ 40.3 ″
Apparent brightness 4.74 likes
Typing
Known exoplanets 3
B − V color index 0.71 
U − B color index 0.26 
R − I index 0.33 
Spectral class G7V
Astrometry
Radial velocity -8.13 km / s
parallax 116.89 ± 0.22  mas
distance 27.90 ± 0.05  ly
8.56 ± 0.02  pc
Visual absolute brightness M vis 5.07 likes
Proper movement 
Rec. Share: −1,070.36  mas / a
Dec. portion: −1,063.69  mas / a
Physical Properties
Dimensions 0.94 ± 0.03 - 0.95 +0.04−0.03 M ☉
radius 0.96 ± 0.01 - 0.98  R ☉
Luminosity

0.85  L ☉

Effective temperature 5,585  K
Metallicity [Fe / H] −0.02
Age 6.1 - 6.6 billion  a
Other names
and catalog entries
Bonn survey BD 17 ° 3813
Bright Star Catalog HR 5019 [1]
Henry Draper Catalog HD 115617 [2]
Gliese catalog FY 506 [3]
Hipparcos catalog HIP 64924 [4]
SAO catalog SAO 157844 [5]
Tycho catalog TYC 6116-1517-1 [6]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS J13182443-1818387 [7]
Other names FK5 1345, GCTP 3039.00, LHS 349, LTT 5111

61 Virginis (abbreviated 61 Vir ) is a yellow dwarf ( spectral class G7V) at a distance of 27.9 light years from the Sun in the constellation Virgo . The star has a little less mass than the sun (spectral class G2V) and its composition is almost identical to it.

61 Virginis was the first star very similar to the Sun in 2009 around which a super-earth could possibly be detected as a planetary companion, according to CoRoT-7 , which, however, belongs to the spectral class K. A total of three exoplanets around 61 Virginis are known.

properties

61 Virginis is a main sequence star of the spectral class G and appears in the sky as a star of 5th magnitude . Despite its weakness of light, it can be seen with the naked eye, southeast of the bright star Spica in the zodiac constellation Virgo. The name "61 Virginis" comes from the star catalog Historia coelestis Britannica published in 1712 by the English astronomer John Flamsteed (→ Flamsteed name ). In 1835, Francis Baily noticed that the star had a proper motion . This made 61 Virginis interesting for parallax studies , and by 1950 an annual mean of 0.006 ″ was determined. Today's value for parallax is 116.89  mas based on measurements from the Hipparcos satellite , which gives a distance of 27.9 light years from the Sun.

61 Virginis is physically similar to the sun. It has around 95% of the solar mass , 98% of the solar radius , and 85% of the sun's luminosity . The abundance of certain elements is also similar to that of the sun. 61 Virginis has an estimated 95% of the sun's share of elements other than hydrogen or helium. At around 6.1 to 6.6 billion years old, the star is older than the Sun and rotates at the equator at a projected speed of 4 km / s. On average, it shows only a low level of activity in its chromosphere and is possibly in a phase comparable to the Maunder minimum . On the other hand, 61 Virginis were classified as presumably changeable in 1988 and an outbreak of activity was observed between November 29, 2008 and January 23, 2010.

The components of the spatial motion of 61 Virginis are U = -37.9, V = -35.3 and W = -24.7 km / s. 61 Virginis orbits within the Milky Way at a distance of 6.9 kiloparsecs from the center with an orbital eccentricity of 0.15. He probably belongs to the disk population .

Planetary system

As can be concluded from the surrounding debris disk , the ecliptic of the planetary system of 61 Virginis is inclined by 77 ° to the solar system . The star itself is likely tilted 72 degrees.

A 1988 study suggested that 61 Virginis may be mutable, but no companions could be found. A follow-up study over eleven years could not detect a companion up to the mass of Jupiter and up to 3 AU from the star.

On December 14, 2009, a group of scientists announced the discovery of three planets between five and twenty-five times the mass of Earth in orbits around 61 Virginis. All three planets orbit their central star at a very short distance. Transferred to the solar system, their orbits would be within the orbit of Venus . The outermost of the planets ( 61 Virginis d ) could not yet by the échelle spectrograph HARPS of ESO confirmed.

The Spitzer Space Telescope revealed an infrared excess at a wavelength of 160 μm. This suggests the existence of a debris disk around 61 Virginis. The disk could be resolved at 70 μm. Initially, an inner radius of 96 AU and an outer radius of 195 AU from the star were assumed, but now between 30 and over 100 AU. The full mass of the debris disk is 5 × 10 −5 times the mass of the earth.

On November 27, 2012, the European Space Agency (ESA) announced that the debris disk of 61 Virginis (like that of Gliese 581 ) contains at least ten times as many comets as in the solar system. The existence of planets with a greater mass than Saturn within 6 AU of the star is currently (as of 2012) excluded. The ESA also rules out the existence of planets with Saturn mass beyond it.

To confirm the possibility of planets smaller than Saturn between 0.5 (0.3) and 30 AU from the star, additional data is required. A planet of earth mass in the habitable zone of 61 Virginis is conceivable, but cannot be discovered with current technology.

Planetary system of 61 Virginis

Planet
(by distance from the star) 		Discovery
(year) 		Mass
(in M ♃ ) 		Cycle time
(in days) 		Major semi-axis
(in AU ) 		eccentricity
61 Virginis b 2009 0.016 ± 0.002 4.2150 ± 0.0006 0.050201 ± 0.000005 0.12 ± 0.11
61 Virginis c 2009 0.057 ± 0.003 38.021 ± 0.034 0.2175 ± 0.0001 0.14 ± 0.06
61 Virginis d 2009 0.072 ± 0.008 123.01 ± 0.55 0.476 ± 0.001 0.35 ± 0.09

Sky sight from 61 Virginis

From 61 Virginis, the Sun is a faintly visible star near the much brighter Sirius . The brightest star in the sky is Arctur with −1.01 mag apparent brightness.

Individual evidence

  1. ^ A b van Leeuwen, F .: Validation of the new Hipparcos reduction . arxiv : 0708.1752 .
  2. ↑ a b Gray, RO et al .: Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I . arxiv : astro-ph / 0308182 .
  3. ↑ Nidever, David L. et al .: radial velocities for 889 late-type stars . arxiv : astro-ph / 0112477 .
  4. ↑ a b c d e f g h i j k Vogt, Steven; Wittenmyer; Paul Butler; Simon O'Toole; Henry; Rivera; Stefano Meschiari; Gregory Laughlin; Tinney: A Super-Earth and two Neptunes Orbiting the Nearby Sun-like star 61 Virginis . arxiv : 0912.2599 .
  5. ↑ a b c Porto de Mello, Gustavo; del Peloso, Eduardo F .; Ghezzi, Luan: Astrobiologically Interesting Stars within 10 parsecs of the Sun . arxiv : astro-ph / 0511180 .
  6. ↑ a b c Perrin, M.-N .; Cayrel de Strobel, G .; Dennefeld, M .: High S / N detailed spectral analysis of four G and K dwarfs within 10 PC of the sun . bibcode : 1988A & A ... 191..237P .
  7. ↑ a b Mamajek, Eric E .; Hillenbrand, Lynne A .: Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics . arxiv : 0807.1686 .
  8. ↑ Baily, Francis: An Account of the Revd. John Flamsteed, the First Astronomer-Royal. Retrieved May 3, 2015 .
  9. ↑ Cape Observatory: Stars, Parallax of: Stellar parallaxes determined photographically at the Cape Observatory (seventeenth list). Retrieved May 3, 2015 .
  10. ↑ Ammler-of Eiff, M .; Reiners, A .: New measurements of rotation and differential rotation in AF stars: Are there two populations of differentially rotating stars? arxiv : 1204.2459 .
  11. ^ Lubin, Dan; Tytler, David; Kirkman, David: Frequency of Maunder Minimum Events in Solar-type Stars Inferred from Activity and Metallicity Observations . bibcode : 2012ApJ ... 747L..32L .
  12. ↑ a b Campbell, Bruce et al .: A search for substellar companions to solar-type stars . bibcode : 1988ApJ ... 331..902C .
  13. ↑ a b c Wyatt, MC et al .: Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems . arxiv : 1206.2370 .
  14. ↑ Cumming, Andrew; Marcy, Geoffrey W .; Butler, R. Paul: The Lick Planet Search: Detectability and Mass Thresholds . arxiv : astro-ph / 9906466 .
  15. ^ University of California, Santa Cruz: New planet discoveries suggest low-mass planets are common around nearby stars. (No longer available online.) Archived from the original on December 23, 2009 ; Retrieved May 3, 2015 .
  16. ^ Tanner, Angelle et al .: Survey of Nearby FGK Stars at 160 microns with Spitzer . arxiv : 0908.0049 .
  17. ↑ European Space Agency: Do missing Jupiters mean massive comet belts? Retrieved May 3, 2015 .
  18. ↑ a b c NASA Exoplanet Archives: 61 Vir. Retrieved May 3, 2015 .

Web links

Commons : 61 Virginis  - Collection of images, videos and audio files