20 Ceti
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 00h 53m 00.49452s[2] |
| Declination | −01° 08′ 39.3317″[2] |
| Apparent magnitude (V) | 4.76[3] |
| Characteristics | |
| Spectral type | K5 III[4] |
| U−B color index | +1.91[5] |
| B−V color index | +1.56[5] |
| Astrometry | |
| Radial velocity (Rv) | +16.22±0.28[6] km/s |
| Proper motion (μ) | RA: +6.99[2] mas/yr Dec.: −15.66[2] mas/yr |
| Parallax (π) | 5.56±0.22 mas[2] |
| Distance | 590 ± 20 ly (180 ± 7 pc) |
| Absolute magnitude (MV) | −1.58[7] |
| Details | |
| Mass | 1.1[8] M☉ |
| Radius | 65.93+2.13 −2.25[9] R☉ |
| Luminosity | 754.8±52.6[9] L☉ |
| Surface gravity (log g) | 1.61[8] cgs |
| Temperature | 4,065[8] K |
| Metallicity [Fe/H] | −0.19[8] dex |
| Other designations | |
| Tianhun, 20 Cet, BD−01°114, FK5 1022, HD 5112, HIP 4147, HR 248, SAO 129009[10] | |
| Database references | |
| SIMBAD | data |
20 Ceti, also named Tianhun,[11] is a single[12] star located around 590[2] light-years away in the equatorial constellation of Cetus. It is faintly visible to the naked eye with apparent magnitude is 4.76.[3] The Bright Star Catalogue has this star classified as M0III,[13] matching an aging red giant star that has consumed the hydrogen at its core and expanded. Houk and Swift (1999) listed an earlier class of K5 III.[4] It has around 66 times the Sun's radius and is radiating about 750 times the Sun's luminosity[9] from its enlarged photosphere at an effective temperature of 4,065 K.[8]
In Chinese astronomy, this star is part of the asterism Tiān Hùn (天溷), Celestial Pigsty. The IAU Working Group on Star Names adopted the name Tianhun for this star on 15 October 2026.[11]
References
[edit]- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- 1 2 3 4 5 6 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.
- 1 2 Ducati, J. R. (2002), "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system", CDS/ADC Collection of Electronic Catalogues, 2237, Bibcode:2002yCat.2237....0D.
- 1 2 Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, Bibcode:1999MSS...C05....0H.
- 1 2 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, Bibcode:1986EgUBV........0M.
- ↑ Famaey, B.; Pourbaix, D.; Frankowski, A.; Van Eck, S.; Mayor, M.; Udry, S.; Jorissen, A. (2009), "Spectroscopic binaries among Hipparcos M giants", Astronomy and Astrophysics, 498 (2): 627, arXiv:0901.0934, Bibcode:2009A&A...498..627F, doi:10.1051/0004-6361/200810698, S2CID 18739721.
- ↑ Groenewegen, M. A. T. (April 2012), "Infrared excess around nearby red giant branch stars and Reimers law", Astronomy & Astrophysics, 540: 21, Bibcode:2012A&A...540A..32G, doi:10.1051/0004-6361/201118287, A32.
- 1 2 3 4 5 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv:2407.06963. Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.
- 1 2 3 Baines, Ellyn K.; Thomas Armstrong, J.; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David; Nisley, Ishara; Sanborn, Jason; Schmitt, Henrique R.; Van Belle, Gerard T. (2021). "Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 162 (5): 198. arXiv:2211.09030. Bibcode:2021AJ....162..198B. doi:10.3847/1538-3881/ac2431. S2CID 238998021.
- ↑ "20 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 26, 2018.
- 1 2 "IAU Catalog of Star Names". Retrieved 18 October 2026.
- ↑ 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.
- ↑ Hoffleit, D.; Warren, Jr., W. H. (1991), The Bright Star Catalogue (5th Revised ed.), New Haven: Yale University Observatory, Bibcode:1991bsc..book.....H.
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