Astronomy:Theta Chamaeleontis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Chamaeleon |
| Right ascension | 08h 20m 38.54055s[1] |
| Declination | −77° 29′ 04.1173″[1] |
| Apparent magnitude (V) | 4.34[2] |
| Characteristics | |
| Spectral type | K2 IIIb CN0.5[3] |
| U−B color index | +1.19[4] |
| B−V color index | +1.16[4] |
| Astrometry | |
| Radial velocity (Rv) | +21.70±0.7[5] km/s |
| Proper motion (μ) | RA: −129.05[1] mas/yr Dec.: +40.89[1] mas/yr |
| Parallax (π) | 21.00 ± 0.14[1] mas |
| Distance | 155 ± 1 ly (47.6 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.97±0.10[2] |
| Details[2] | |
| Mass | 0.94±0.27 M☉ |
| Radius | 11.5 R☉ |
| Luminosity | 60[6] 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,[7] 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.[2] Parallax measurements by the Hipparcos spacecraft put the system at 155 light-years, or 47.6 parsecs away.[1] It is moving away from the Sun with a radial velocity of +22 km/s.[5]
Theta Chamaeleontis is an evolved K-type giant star with a stellar classification of K2 IIIb CN0.5,[3] 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.[2] The star is radiating 60[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,570 K.[2]
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.[8]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 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. Bibcode: 1999A&A...352..555A.
- ↑ 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K.
- ↑ 4.0 4.1 Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99. Bibcode: 1966CoLPL...4...99J.
- ↑ 5.0 5.1 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G.
- ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ 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. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M.
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