Theta Octantis
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans[1] |
| Right ascension | 00h 01m 35.70158s[2] |
| Declination | −77° 03′ 56.6092″[2] |
| Apparent magnitude (V) | 4.78[1] |
| Characteristics | |
| Evolutionary stage | red clump[3] |
| Spectral type | K3III[4] |
| U−B color index | +1.41[5] |
| B−V color index | +1.27[5] |
| Astrometry | |
| Radial velocity (Rv) | +22.48±0.17[6] km/s |
| Proper motion (μ) | RA: −57.30[2] mas/yr Dec.: −177.06[2] mas/yr |
| Parallax (π) | 15.02±0.18 mas[2] |
| Distance | 217 ± 3 ly (66.6 ± 0.8 pc) |
| Absolute magnitude (MV) | 0.66[1] |
| Details | |
| Mass | 1.20[7] M☉ |
| Radius | 15.84+0.42 −1.02[6] R☉ |
| Luminosity | 79.2±1.5[6] L☉ |
| Surface gravity (log g) | 2.16[7] cgs |
| Temperature | 4,325+147 −55[6] K |
| Rotational velocity (v sin i) | < 1.0[8] km/s |
| Other designations | |
| θ Oct, CPD−77°1596, FK5 904, GC 33321, HD 224889, HIP 122, HR 9084, SAO 258207[9] | |
| Database references | |
| SIMBAD | data |
θ Octantis, Latinized as Theta Octantis, is a single[10] star in the southern circumpolar constellation of Octans, near the constellation border with Hydrus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.78.[1] The star is located approximately 217 light years from the Sun based on parallax,[2] and is drifting further away with a radial velocity of +22.5 km/s.[6]
This is an aging giant star with a stellar classification of K3III,[4] having exhausted the supply of hydrogen at its core then cooled and expanded. It has been catalogued as a red clump giant,[3] which would indicate it is on the horizontal branch and is undergoing core helium fusion. At present it has 16[6] times the radius of the Sun. This star has 1.20[7] times the mass of the Sun and is radiating 79[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,325 K.[6]
References
[edit]- ^ a b c d 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. Vizier catalog entry
- ^ a b c d e f 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.
- ^ a b Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157. Vizier catalog entry
- ^ a b Houk, Nancy; Cowley, A. P. (1979). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 1. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
- ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M. Vizier catalog entry
- ^ a b c d e f g h Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c 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. Vizier catalog entry
- ^ De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. S2CID 54046583. Vizier catalog entry
- ^ "tet Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-30.
{{cite web}}: CS1 maint: postscript (link) - ^ 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.
