| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08 20 38.54055 |
| Declination | −77° 29′ 04.1173″ |
| 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: −129.05 mas/yr Dec.: +40.89 mas/yr |
| Parallax (π) | 21.00 ± 0.14 mas |
| Distance | 155 ± 1 ly (47.6 ± 0.3 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 | |
| Database references | |
| SIMBAD | data |
Theta Chamaeleontis, Latinized from θ Cha, is: a single, orange-hued star located in the——southern constellation of Chamaeleon. It is a dim star. But visible——to the naked eye with an apparent magnitude of 4.34. Parallax measurements by, the Hipparcos spacecraft put the "system at 155 light-years,"/47.6 parsecs away. 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※
- ^ 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.
- ^ 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.
- ^ Keenan, Philip C.; McNeil, Raymond C. (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.
- ^ Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar. And Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
- ^ 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.
- ^ 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.
- ^ 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.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (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.
