Beta Comae Berenices

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Beta Comae Bernices
Coma Berenices constellation map.png
Location of β Coma Bernices (upper left)
Observation data
Epoch J2000      Equinox J2000
Constellation Coma Berenices
Right ascension 13h 11m 52.39379s[1]
Declination +27° 52′ 41.4535″[1]
Apparent magnitude (V) 4.26[2]
Characteristics
Spectral type G0 V[3]
U−B color index +0.08[2]
B−V color index +0.58[4]
Astrometry
Radial velocity (Rv) +6.1[5] km/s
Proper motion (μ) RA: -801.44[1] mas/yr
Dec.: +882.04[1] mas/yr
Parallax (π) 109.54 ± 0.17[1] mas
Distance 29.78 ± 0.05 ly
(9.13 ± 0.01 pc)
Details
Mass 1.15[6] M
Radius 1.106 ± 0.011[7] R
Luminosity 1.357 ± 0.014[7] L
Surface gravity (log g) 4.38[4] cgs
Temperature 5,936 ± 33[7] K
Metallicity [Fe/H] +0.07[4] dex
Rotational velocity (v sin i) 4.10 ± 0.06[8] km/s
Age 1.5–2.5[9] Gyr
Other designations
43 Com, Beta Com, BD +28°2193, FK5 492, GCTP 3015.00, Gl 502, GJ 502, HD 114710, HIP 64394, HR 4983, LFT 978, LHS 348, LTT 13815, SAO 82706.[10]

Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices. It is located at a distance of about 29.78 light-years (9.13 parsecs) from Earth. The Greek letter beta (β) usually indicates that the star has the second highest visual magnitude in the constellation. However, with an apparent visual magnitude of 4.3,[2] this star is slightly brighter than α Comae Berenices. It can be seen with the naked eye, but may be too dim to be viewed from a built-up urban area.

This star is similar to our own Sun, being only slightly larger and brighter in absolute magnitude. It has a stellar classification of G0 V,[3] compared to G2 V for the Sun. The effective temperature of the outer envelope is 5,936 K,[7] giving it a yellow hue of a G-type star.[11] In terms of age it is younger than the Sun, being about 3 billion years old.[9]

Observations of short term variations in the chromatic activity suggest that the star undergoes differential rotation,[12] with a rotation period of about 11–13 days.[8] Its surface has a measured activity cycle of 16.6 years, compared to 11 years on our Sun. It may also have a secondary activity cycle of 9.6 years.[13] At one time it was thought that this star might have a spectroscopic companion. However, this was ruled out by means of more accurate radial velocity measurements. No planets have yet been detected around it, and there is no evidence of a dusty disk.

References[edit]

  1. ^ a b c d e van Leeuwen, Floor (November 2007), Validation of the new Hipparcos reduction, Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752v1, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357  Note: see VizieR catalogue I/311.
  2. ^ a b c Johnson, H. L. et al. (1966), UBVRIJKL photometry of the bright stars, Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode:1966CoLPL...4...99J 
  3. ^ a b Gray, R. O.; Napier, M. G.; Winkler, L. I. (April 2001), The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars, The Astronomical Journal 121 (4): 2148–2158, Bibcode:2001AJ....121.2148G, doi:10.1086/319956 
  4. ^ a b c Mallik, Sushma V. (October 1998). "Chromospheric activity in cool stars and the lithium abundance". Astronomy and Astrophysics 338: 623–636. Bibcode:1998A&A...338..623M. 
  5. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495..... 
  6. ^ Takeda, G. et al. (2007). "Stellar parameters of nearby cool stars. II. Physical properties of ~1000 cool stars from the SPOCS catalog". Astrophysical Journal Supplement Series 168: 297–318. Bibcode:2008yCat..21680297T. doi:10.1086/509763.  Note: see VizieR catalogue J/ApJS/168/297.
  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 Gray, David F.; Baliunas, Sallie L. (January 1997), The Rotation of the G0 Dwarf beta Comae, Astrophysical Journal 475: 303–312, Bibcode:1997ApJ...475..303G, doi:10.1086/303522 
  9. ^ a b Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. 
  10. ^ LHS 348 -- High proper-motion Star, SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-02-04 
  11. ^ The Colour of Stars, Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 
  12. ^ Donahue, Robert A.; Baliunas, Sallie L. (July 1992), Evidence of differential surface rotation in the solar-type star HD 114710, Astrophysical Journal, Part 2 - Letters 393 (2): L63–L66, Bibcode:1992ApJ...393L..63D, doi:10.1086/186452 
  13. ^ Baliunas, S. L. et al. (January 1995), Chromospheric variations in main-sequence stars, Astrophysical Journal, Part 1 438 (1): 269–287, Bibcode:1995ApJ...438..269B, doi:10.1086/175072  See appendix A.

External links[edit]