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Theta Chamaeleontis is a single,[8] orange-hued star located in the southern constellation of Chamaeleon. Its name is a Bayer designation that is Latinized from θ Chamaeleontis, and abbreviated Theta Cha or θ Cha. This is a dim star but visible to the naked eye with an apparent magnitude of 4.34.[3] Parallax measurements put the star at a distance of 152.8 light-years (46.8 pc).[2] It is moving away from the Sun with a radial velocity of +22 km/s.[6]

Theta Chamaeleontis is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5,[4] where the suffix notation indicates the outer atmosphere has a mild overabundance of cyanogen. It has 0.94 times the mass of the Sun, and has expanded to 11.5 times as wide.[3] The star is radiating 60[1] times the Sun’s luminosity from its enlarged photosphere at an effective temperature of 4,570 K.[3]

It has a visual companion, Theta Chamaeleontis B. This is a magnitude 12.44 star at an angular separation of 21.1 arcseconds from component A along a position angle of 237°, as of 2000.[9]

References

  1. ^ a b c 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. XHIP record for this object at VizieR.
  2. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). “Gaia Data Release 3. Summary of the content and survey properties”. Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A…674A…1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d e f Allende Prieto, C.; Lambert, D. L. (1999). “Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures”. Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A…352..555A.
  4. ^ a b Keenan, Philip C.; et al. (1989). “The Perkins catalog of revised MK types for the cooler stars”. Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS…71..245K. doi:10.1086/191373.
  5. ^ a b Johnson, H. L. (1966). “UBVRIJKL Photometry of the Bright Stars”. Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL…4…99J.
  6. ^ a b Gontcharov, G. A. (2006). “Pulkovo Compilation of Radial Velocities for 35 495 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.
  7. ^ “tet Cha”. SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-03-02.
  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. ^ Mason, Brian D.; et al. (2001). “The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog”. The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ….122.3466M. doi:10.1086/323920.