Theta Chamaeleontis
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Chamaeleon[1] |
| Right ascension | 08h 20m 38.539s[2] |
| Declination | −77° 29′ 04.125″[2] |
| Apparent magnitude (V) | 4.34[3] |
| Characteristics | |
| Spectral type | K2 IIIb CN0.5[4] |
| U−B color index | +1.19[5] |
| B−V color index | +1.16[5] |
| Astrometry | |
| Radial velocity (Rv) | +21.70±0.7[6] km/s |
| Proper motion (μ) | RA: −129.048 mas/yr[2] Dec.: +40.598 mas/yr[2] |
| Parallax (π) | 21.3462±0.1010 mas[2] |
| Distance | 152.8 ± 0.7 ly (46.8 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.97±0.10[3] |
| Details[3] | |
| Mass | 0.94±0.27 M☉ |
| Radius | 11.5 R☉ |
| Luminosity | 60[1] L☉ |
| Surface gravity (log g) | 2.29±0.29 cgs |
| Temperature | 4,570 K |
| Other designations | |
| θ Cha, CPD−77°383, FK5 318, HD 71701, HIP 40888, HR 3340, SAO 256503[7] | |
| Database references | |
| SIMBAD | data |
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
[edit]- 1 2 3 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.
- 1 2 3 4 5 6 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.
- 1 2 3 4 5 6 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.
- 1 2 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.
- 1 2 Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
- 1 2 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.
- ↑ "tet Cha". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2026-03-02.
- ↑ 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.
- ↑ 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.
