Beta Canum Venaticorum

From Wikipedia, the free encyclopedia

Beta Canum Venaticorum
Observation data
Epoch J2000
Constellation
(pronunciation)		 Canes Venatici
Right ascension 12h 33m 44.5446s
Declination +41° 21′ 26.927″
Apparent magnitude (V) 4.26
Characteristics
Spectral type G0 V
U-B color index 0.04[1]
B-V color index 0.58[1]
Variable type Suspected
Astrometry
Radial velocity (Rv) +6.9 km/s
Proper motion (μ) RA: -705.06 mas/yr
Dec.: 292.93 mas/yr
Parallax (π) 119.19 ± 0.83 mas
Distance 27.4 ± 0.2 ly
(8.39 ± 0.06 pc)
Absolute magnitude (MV) 4.65
Details
Mass 1.08 M☉
Radius 1.18 ± 0.11[2] R☉
Surface gravity (log g) 4.60[3]
Luminosity 1.15[4] L☉
Temperature 6,045[3] K
Metallicity [Fe/H] = −0.21[3]
Rotation < 3 km/s
Age 5.3×109[5] years
Other designations
Chara, Asterion, Beta CVn, 8 CVn, Gl 475, HR 4785, BD +42°2321, HD 109358, LHS 2579, LTT 13552, GCTP 2895.00, SAO 44230, FK5 470, LFT 924, NSV 5725, HIP 61317.
Database references
SIMBAD data
ARICNS data

Beta Canum Venaticorum (β CVn / β Canum Venaticorum) is a yellow G-type main sequence dwarf star in the constellation Canes Venatici. It is the second-brightest star in the constellation.

Along with the brighter star Cor Caroli, the pair form the "southern dog" in this constellation that represents hunting dogs. The name Chara was originally applied to the "southern dog", but it later became used specifically to refer to Beta Canum Venaticorum. Chara means Joy in the Greek language.[6]

Contents

[edit] Observations

β CVn is considered to be slightly metal-poor,[3] which means it has a somewhat lower portion of elements heavier than Helium when compared to the Sun. In terms of mass, age and evolutionary status, however, this star is very similar to the Sun.[7] As a result it has been called a solar analog.

The components of this star's space velocity are U=−25, V=0 and W=+2 km/s.[4] In the past it was suggested that this star may be a spectroscopic binary. However, further analysis of the data does not seem to bear that out.[8] In addition, a search for a brown dwarf in orbit around this star failed to discover any such companion, at least down to the sensitivity limit of the instrument used.[9]

The spectrum of this star shows a very weak emission of singly-ionized Calcium (Ca II) from the chromosphere, making it a useful reference star for a reference spectrum to compare with other stars in a similar spectral category.[10] (The Ca II emission lines are readily accessible and can be used to measure the level of activity in a star's chromosphere.)

[edit] Possibility of life

In 2006, astronomer Margaret Turnbull labelled Beta CVn as the top stellar system top candidate to search for extraterrestrial life forms.[11] Because of its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun.[4]

[edit] References

  1. ^ a b Argue, A. N. (1966). "UBV photometry of 550 F, G and K type stars". Monthly Notices of the Royal Astronomical Society 133: 475–493. 
  2. ^ Perrin, M.-N.; Karoji, H. (1987). "Stellar radius determination from IRAS 12-micron fluxes". Astronomy and Astrophysics 172: 235–240. 
  3. ^ a b c d Luck, R. Earle; Heiter, Ulrike (2006). "Dwarfs in the Local Region". The Astronomical Journal 131 (2): 3069–3092. doi:10.1086/504080. 
  4. ^ a b c de Mello, G. P.; del Peloso, E. F.; Ghezzi, L. (2006). "Astrobiologically Interesting Stars Within 10 Parsecs of the Sun" (abstract). Astrobiology 6 (2): 308–331. doi:10.1089/ast.2006.6.308. 
  5. ^ Barry, Don C.; Cromwell, Richard H.; Hege, E. Keith (1987). "Chromospheric activity and ages of solar-type stars". Astrophysical Journal, Part 1 315: 264–272. doi:10.1086/165131. 
  6. ^ Kaler, Jim. Beta Canum Venaticorum. Stars. Retrieved on 2006-12-06.
  7. ^ G. F. Porto de Mello, E. F. del Peloso, L. Ghezzi (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun" (abstract). Astrobiology 6 (2): 308–331. doi:10.1089/ast.2006.6.308. 
  8. ^ Morbey, C. L.; Griffin, R. F. (1987). "On the reality of certain spectroscopic orbits". Astrophysical Journal, Part 1 317: 343–352. doi:10.1086/165281. 
  9. ^ Carson, J. C.; Eikenberry, S. S.; Brandl, B. R.; Wilson, J. C.; Hayward, T. L. (2006). "The Cornell High-Order Adaptive Optics Survey for Brown Dwarfs in Stellar Systems. I. Observations, Data Reduction, and Detection Analyses". The Astronomical Journal 130: 31212–1220. doi:10.1086/432604. 
  10. ^ Herbig, G. H. (1985). "Chromospheric H-alpha emission in F8-G3 dwarfs, and its connection with the T Tauri stars". Astrophysical Journal 289 (1): 269–278. doi:10.1086/162887. 
  11. ^ "Stars searched for extraterrestrials", PhysOrg.com, February 19, 2006. Retrieved on 2008-05-04. 

[edit] External links

Sirius  This main sequence star-related article is a stub. You can help Wikipedia by expanding it.