Gamma Chamaeleontis

From Wikipedia, the free encyclopedia
Jump to: navigation, search
γ Chamaeleontis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Chamaeleon
Right ascension 10h 35m 28.10720s[1]
Declination −78° 36′ 28.0321″[1]
Apparent magnitude (V) 4.12[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.94[2]
B−V color index +1.57[2]
Astrometry
Radial velocity (Rv) −22.4[4] km/s
Proper motion (μ) RA: −37.61[1] mas/yr
Dec.: +11.08[1] mas/yr
Parallax (π) 7.81 ± 0.12[1] mas
Distance 418 ± 6 ly
(128 ± 2 pc)
Details
Radius 67[5] R
Luminosity 864[6] L
Temperature 4,035[6] K
Other designations
γ Cha, CD−77° 454, FK5 401, HD 92305, HIP 51839, HR 4174, SAO 256731.[7]
Database references
SIMBAD data

Gamma Chamaeleontis (γ Cha), is a solitary[8] star located in the southern circumpolar constellation of Chamaeleon. It can faintly be seen with the naked eye on a dark night, having an apparent visual magnitude of 4.12.[2] Based upon an annual parallax shift of 7.81 mas,[1] it is located around 418 light years from the Sun.

This is an evolved K-type giant star with a stellar classification of K5 III.[3] The measured angular diameter, after correction for limb darkening, is 4.86±0.05 mas.[9] At the estimated distance of the star, this yields a physical size of about 67 times the radius of the Sun.[5] It is a suspected variable star, with an amplitude of 0.01 magnitude.[10] The star radiates 864 times the solar luminosity from its outer atmosphere with an effective temperature of 4,053 K.[6]

In the next 7500 years, the south Celestial pole will pass close to this stars (4200 CE).[citation needed]

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Houk, N.; Cowley, A. P. (1975), "Catalogue of two-dimensional spectral types for the HD stars", University of Michigan, I, Bibcode:1975MSS...C01....0H. 
  4. ^ Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W. 
  5. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1.  The radius (R*) is given by:
  6. ^ a b c McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  7. ^ "gam Cha -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-11. 
  8. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  9. ^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039. 
  10. ^ Eggen, O. J. (1973), "The classification of intrinsic variables. IV. Very-small-amplitude, very-short-period red variables", Astrophysical Journal, 184: 793, Bibcode:1973ApJ...184..793E, doi:10.1086/152371.