Beta Canum Venaticorum

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Beta Canum Venaticorum
Diagram showing star positions and boundaries of the Auriga constellation and its surroundings
Cercle rouge 100%.svg

The location of β Canum Venaticorum (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Canes Venatici
Right ascension 12h 33m 44.54482s[1]
Declination +41° 21′ 26.9248″[1]
Apparent magnitude (V) 4.26[2]
Characteristics
Spectral type G0 V[2]
U−B color index 0.04[3]
B−V color index 0.58[3]
Astrometry
Radial velocity (Rv) +6.9[4] km/s
Proper motion (μ) RA: –704.75[1] mas/yr
Dec.: +292.74[1] mas/yr
Parallax (π) 118.49 ± 0.20[1] mas
Distance 27.53 ± 0.05 ly
(8.44 ± 0.01 pc)
Absolute magnitude (MV) 4.64[5]
Details
Mass 1.025 ± 0.050[6] M
Radius 1.123 ± 0.028[7] R
Luminosity 1.151 ± 0.018[7] L
Surface gravity (log g) 4.60[8] cgs
Temperature 5,653 ± 72[7] K
Metallicity [Fe/H] –0.21[8] dex
Rotational velocity (v sin i) 2.9 ± 0.4[9] km/s
Age 5.3[10] to 7.1[5] Gyr
Other designations
Chara, Asterion, Beta CVn, 8 CVn, BD +42 2321, FK5 470, HD 109358, HIP 61317, HR 4785, SAO 44230.[2]
Database references
SIMBAD data
ARICNS data

Beta Canum Venaticorum (β CVn, β Canum Venaticorum) is a G-type main-sequence star in the northern constellation Canes Venatici. At an apparent visual magnitude of 4.26,[2] it is the second-brightest star in this relatively faint constellation. Based upon an annual parallax shift of 118.49 mas,[1] this star is 27.53 light-years (8.44 parsecs) distant from the Earth.

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 (χαρά) means Joy in Greek.[11]

In Chinese, 常陳 (Cháng Chén), meaning Imperial Guards, refers to an asterism consisting of β Canum Venaticorum, α Canum Venaticorum, 10 Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum, and 67 Ursae Majoris.[12] Consequently, β Canum Venaticorum itself is known as 常陳四 (Cháng Chén sì, English: the Fourth Star of Imperial Guards.)[13]

Observations[edit]

At apparent magnitude 4.26, Beta Canum Venaticorum is the second brightest star in the constellation. It has a stellar classification of G0 V, and so is a G-type main sequence star. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[14] The spectrum of this star shows a very weak emission line 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.[15] (The Ca-II emission lines are readily accessible and can be used to measure the level of activity in a star's chromosphere.)

β CVn is considered to be slightly metal-poor,[8] 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.[16] As a result it has been called a solar analog. It is about 3% more massive than the Sun,[6] with a radius 12% larger than the Sun's and 15% greater luminosity.[7]

The components of this star's space velocity are (U, V, W) = (–25, 0, +2) km/s.[16] In the past it was suggested that it may be a spectroscopic binary. However, further analysis of the data does not seem to bear that out.[17] 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.[18]

Possibility of life[edit]

In 2006, astronomer Margaret Turnbull labeled Beta CVn as the top stellar system candidate to search for extraterrestrial life forms.[19] Because of its solar-type properties, astrobiologists have listed it among the most astrobiologically interesting stars within 10 parsecs of the Sun.[16] However, as of 2009, this star is not known to host planets.[6]

Chara and Asterion in Military[edit]

Chara and Asterion is used for the name of three United States navy ships: USS Asterion (AK-100), USS Asterion (AF-63) and USS Chara (AKA-58).

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d "bet CVn -- Spectroscopic binary". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-07-04. 
  3. ^ 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. Bibcode:1966MNRAS.133..475A. 
  4. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495..... 
  5. ^ a b Holmberg, J.; Nordström, B.; Andersen, J. (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. 
  6. ^ a b c van Belle, Gerard T.; von Braun, Kaspar (April 2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars". The Astrophysical Journal 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085. 
  7. ^ a b c d Boyajian, Tabetha S. et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101. . See Table 10.
  8. ^ a b c Luck, R. Earle; Heiter, Ulrike (2006). "Dwarfs in the Local Region". The Astronomical Journal 131 (2): 3069–3092. Bibcode:2006AJ....131.3069L. doi:10.1086/504080. 
  9. ^ Herrero, E. et al. (January 2012), "Optimizing exoplanet transit searches around low-mass stars with inclination constraints", Astronomy & Astrophysics 537: A147, arXiv:1110.5840, Bibcode:2012A&A...537A.147H, doi:10.1051/0004-6361/201117809. 
  10. ^ 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. Bibcode:1987ApJ...315..264B. doi:10.1086/165131. 
  11. ^ Kaler, Jim. "Beta Canum Venaticorum". Stars. University of Illinois. Retrieved 2006-12-06. 
  12. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  13. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  14. ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode:1993AAS...183.1710G, retrieved 2012-02-04. 
  15. ^ 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. Bibcode:1985ApJ...289..269H. doi:10.1086/162887. 
  16. ^ a b c de Mello, G. P.; del Peloso, E. F.; Ghezzi, L. (2006). "Astrobiologically Interesting Stars Within 10 Parsecs of the Sun". Astrobiology (abstract) 6 (2): 308–331. arXiv:astro-ph/0511180. Bibcode:2006AsBio...6..308P. doi:10.1089/ast.2006.6.308. PMID 16689649. 
  17. ^ Morbey, C. L.; Griffin, R. F. (1987). "On the reality of certain spectroscopic orbits". Astrophysical Journal, Part 1 317: 343–352. Bibcode:1987ApJ...317..343M. doi:10.1086/165281. 
  18. ^ Carson, J. C. et al. (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 (3): 1212–1220. arXiv:astro-ph/0506287. Bibcode:2005AJ....130.1212C. doi:10.1086/432604. 
  19. ^ "Stars searched for extraterrestrials". PhysOrg.com. 2006-02-19. Retrieved 2008-05-04. 

External links[edit]