Iota Chamaeleontis

ι Chamaeleontis, Latinized as Iota Chamaeleontis, is a single[8] star in the southern circumpolar constellation of Chamaeleon. It is visible to the naked eye as a dim, yellow-white hued point of light, having an apparent magnitude of about 5.3.[2] Based upon parallax measurements,[1] this star is around 188 light years away from the Sun, but it is drifting closer with a radial velocity of −4 km/s.[1]

Iota Chamaeleontis
Location of ι Chamaeleontis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Chamaeleon
Right ascension 09h 24m 09.22580s[1]
Declination −80° 47′ 12.7597″[1]
Apparent magnitude (V) 5.34[2]
Characteristics
Spectral type F3/5 III/V[3]
U−B color index +0.01[4]
B−V color index +0.454±0.003[2]
Astrometry
Radial velocity (Rv)−3.57±0.66[1] km/s
Proper motion (μ) RA: -138.690[1] mas/yr
Dec.: +134.928[1] mas/yr
Parallax (π)17.3878 ± 0.0925 mas[1]
Distance187.6 ± 1.0 ly
(57.5 ± 0.3 pc)
Absolute magnitude (MV)+1.52[2]
Details
Radius3.63+0.10
−0.13[1] R☉
Luminosity20.244±0.136[1] L☉
Temperature6,429+63
−90[1] K
Metallicity [Fe/H]−0.04[5] dex
Rotational velocity (v sin i)129.7[6] km/s
Age1.2±0.1[2] Gyr
Other designations
ι Cha, CD−80°329, FK5 2753, GC 13066, HD 82554, HIP 46107, HR 3795, SAO 258530[7]
Database references
SIMBADdata

Spectra of the star taken in different years have been given types of F3IV/V and F5III, leading to a mean published type of F3/5 III/V, with the suspicion that the spectrum is variable. It is an F-type star, likely an evolving subgiant.[9] It is 1.2[2] billion years old with 3.6[1] times the Sun's radius. The star has a high rate of spin with a projected rotational velocity of 130 km/s,[6] which is giving it an oblate shape with an equatorial bulge some 9% larger than the polar radius.[10] It is radiating over 20[1] times the Sun's luminosity from its photosphere at an effective temperature of 6,429 K.[1] An infrared excess suggests a circumstellar disk of dust is orbiting at a distance of 8.3 AU from the star with a mean temperature of 200 K.[11]

References
  1. 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.
  2. 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.
  3. Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0. Bibcode:1975mcts.book.....H.
  4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Nordström, B.; et al. (2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs". Astronomy and Astrophysics. 418: 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. S2CID 11027621.
  6. Reiners, Ansgar (January 2006), "Rotation- and temperature-dependence of stellar latitudinal differential rotation", Astronomy and Astrophysics, 446 (1): 267–277, arXiv:astro-ph/0509399, Bibcode:2006A&A...446..267R, doi:10.1051/0004-6361:20053911, S2CID 8642707
  7. "iot Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 January 2016.
  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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  9. Allen, J. S. "The Classification of Stellar Spectra". UCL Department of Physics and Astronomy: Astrophysics Group. Retrieved 1 January 2014.
  10. van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. S2CID 119273474.
  11. Cotten, Tara H.; Song, Inseok (July 2016). "A Comprehensive Census of Nearby Infrared Excess Stars". The Astrophysical Journal Supplement Series. 225 (1): 24. arXiv:1606.01134. Bibcode:2016ApJS..225...15C. doi:10.3847/0067-0049/225/1/15. S2CID 118438871. 15.
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