Alpha Chamaeleontis

Alpha Chamaeleontis, Latinized from α Chamaeleontis, is a solitary[10] star in the southern circumpolar constellation of Chamaeleon. It has an apparent visual magnitude of 4.06[2] and thus is bright enough to be seen with the naked eye. With an annual parallax shift of 51.12 mas,[1] it is located 63.8 light years from the Sun. The star is drifting closer with a radial velocity of −13 km/s,[4] and is predicted to come to within 47 light-years in 666,000 years.[5]

α Chamaeleontis
Location of α Chamaeleontis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Chamaeleon
Right ascension 08h 18m 31.55319s[1]
Declination −76° 55′ 10.9964″[1]
Apparent magnitude (V) 4.06[2]
Characteristics
Spectral type F5 V Fe-0.8[3]
U−B color index −0.04[2]
B−V color index +0.40[2]
Astrometry
Radial velocity (Rv)−13.4±0.5[4] km/s
Proper motion (μ) RA: 111.12[1] mas/yr
Dec.: 107.49[1] mas/yr
Parallax (π)51.12 ± 0.12 mas[1]
Distance63.8 ± 0.1 ly
(19.56 ± 0.05 pc)
Absolute magnitude (MV)+2.59[5]
Details
Mass1.42[6] M☉
Radius2.11+0.14
−0.05[7] R☉
Luminosity7.542±0.062[7] L☉
Surface gravity (log g)4.28±0.14[6] cgs
Temperature6,580+91
−209[7] K
Metallicity [Fe/H]−0.26[3] dex
Rotational velocity (v sin i)0[8] km/s
Age1.8[6] Gyr
Other designations
α Cha, Alf Cha, CPD−76° 507, GJ 305, HD 71243, HIP 40702, HR 3318, SAO 256496[9]
Database references
SIMBADdata

This is an F-type main sequence star with a stellar classification of F5 V Fe−0.8,[3] where the 'Fe−0.8' notation indicates an anomalously low abundance of iron. It has an estimated 1.4 times the mass of the Sun,[6] 2.1 times the Sun's radius,[7] and radiates 7.5 times the solar luminosity from its outer atmosphere at an effective temperature of 6,580 K.[7] The star is around 1.8[6] billion years old with a projected rotational velocity that is too low to be measured.[8] The star has been examined for an infrared excess that would suggest the presence of an orbiting debris disk, but none was found.[11]

References
  1. van Leeuwen, F. (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, S2CID 18759600.
  2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. Gray, R. O.; et al. (2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–70, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  7. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", Contributions from the Institute of Astrophysics and Kwasan Observatory, University of Kyoto, Bibcode:1970crvs.book.....U.
  9. "alf Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-12-10.{{cite web}}: CS1 maint: postscript (link)
  10. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  11. Gáspár, András; et al. (May 2013), "The Collisional Evolution of Debris Disks", The Astrophysical Journal, 768 (1): 29, arXiv:1211.1415, Bibcode:2013ApJ...768...25G, doi:10.1088/0004-637X/768/1/25, S2CID 119295265, 25.
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