Theta Chamaeleontis
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 20m 38.539s |
| Declination | −77° 29′ 04.125″ |
| Apparent magnitude (V) | 4.34 |
| Characteristics | |
| Spectral type | K2 IIIb CN0.5 |
| U−B color index | +1.19 |
| B−V color index | +1.16 |
| Astrometry | |
| Radial velocity (Rv) | +21.70±0.7 km/s |
| Proper motion (μ) | RA: −129.048 mas/yr Dec.: +40.598 mas/yr |
| Parallax (π) | 21.3462±0.1010 mas |
| Distance | 152.8 ± 0.7 ly (46.8 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.97±0.10 |
| Details | |
| Mass | 0.94±0.27 M☉ |
| Radius | 11.5 R☉ |
| Luminosity | 60 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 | |
| Database references | |
| SIMBAD | data |
Theta Chamaeleontis is a single, 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. Parallax measurements put the star at a distance of 152.8 light-years (46.8 pc). It is moving away from the Sun with a radial velocity of +22 km/s.
Theta Chamaeleontis is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5, 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. The star is radiating 60 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,570 K.
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.
References
- 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.
