Theta Leonis
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Leo |
| Right ascension | 11h 14m 14.40446s[1] |
| Declination | +15° 25′ 46.4541″[1] |
| Apparent magnitude (V) | +3.324[2] |
| Characteristics | |
| Spectral type | A2 V[3] |
| U−B color index | +0.07[2] |
| B−V color index | –0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | +7.6[4] km/s |
| Proper motion (μ) | RA: -60.31[1] mas/yr Dec.: -79.10[1] mas/yr |
| Parallax (π) | 19.76±0.17 mas [1] |
| Distance | 165 ± 1 ly (50.6 ± 0.4 pc) |
| Absolute magnitude (MV) | −0.19[5] |
| Details[6] | |
| Mass | 2.8±0.1 M☉ |
| Radius | 4.03±0.10 R☉ |
| Luminosity | 118±5 L☉ |
| Surface gravity (log g) | 3.65[7] cgs |
| Temperature | 9,480±120 K |
| Metallicity [Fe/H] | +0.05[7] dex |
| Rotational velocity (v sin i) | 23[8] km/s |
| Age | 407±12 Myr |
| Other designations | |
| Chertan, Chort, Coxa, θ Leo, Theta Leo, 70 Leo, HR 4359, BD+16 2234, HD 97633, SAO 99512, FK5 423, HIP 54879.[9] | |
| Database references | |
| SIMBAD | data |
Theta Leonis, Latinized from θ Leonis, formally named Chertan,[10] is a star in the constellation of Leo. With an apparent visual magnitude of +3.324[2] it is visible to the naked eye and forms one of the brighter stars in the constellation. The distance from the Sun can be directly determined from parallax measurements, yielding a value of about 165 light-years (51 parsecs).[1]
Description
[edit ]This is a large star with 2.8 times the mass of the Sun and four times the Sun's radius.[6] The spectrum matches a stellar classification of A2 V,[3] making this a seemingly typical A-type main sequence star. However, the spectrum shows enhanced absorption lines of metals, marking this as a chemically peculiar Am star.[11] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, appears around 12% higher than in the Sun.[7] It is radiating 118 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 9,480 K,[6] literally giving it a white-hot glow.[12]
Theta Leonis is much younger than the Sun, with an estimated age of around 550 million years.[7] It has a moderately high rate of rotation, with a projected rotational velocity of 23 km s−1.[8] However, interferometric observations suggest that it is a rapidly rotating star being viewed nearly pole-on.[6] Measurements in the infrared band show an excess of emission from the star and its surroundings, suggesting the presence of a circumstellar disk of dust. The temperature of this emission indicates the disk has an orbital radius of 36 AU.[7]
Nomenclature
[edit ]θ Leonis (Latinised to Theta Leonis) is the star's Bayer designation.
It bore the traditional names Chertan, Chort /ˈtʃɔːrt/ [13] and Coxa /ˈkɒksə/ .[14] Chertan is derived from the Arabic al-kharātān 'two small ribs', originally referring to Delta Leonis and Theta Leonis; Chort from Arabic al-kharāt or al-khurt 'small rib', and Coxa is Latin for 'hip'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[16] included a table of the first two batches of names approved by the WGSN; which included Chertan for this star.
In Chinese, 太微右垣 (Tài Wēi Yòu Yuán), meaning Right Wall of Supreme Palace Enclosure , refers to an asterism consisting of Theta Leonis, Beta Virginis, Sigma Leonis, Iota Leonis and Delta Leonis.[17] Consequently, the Chinese name for Theta Leonis itself is 太微右垣四 (Tài Wēi Zuǒ Yuán sì, English: the Fourth Star of Right Wall of Supreme Palace Enclosure.),[18] representing 西次相 (Xīcìxiāng), meaning The Second Western Minister.[19] 西次相 (Xīcìxiāng), spelled Tsze Seang by R.H. Allen, means "the Second Minister of State" [20]
References
[edit ]- ^ a b c d e f van Leeuwen, F. (November 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 c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
- ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
- ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W
- ^ 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.
- ^ a b c d Maestro, V.; Che, X.; Huber, D.; Ireland, M. J.; Monnier, J. D.; White, T. R.; Kok, Y.; Robertson, J. G.; Schaefer, G. H.; Brummelaar, T. A. T.; Tuthill, P. G. (2013), "Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties", Monthly Notices of the Royal Astronomical Society, 434 (2): 1321, arXiv:1306.5937 , Bibcode:2013MNRAS.434.1321M, doi:10.1093/mnras/stt1092 , S2CID 2361434
- ^ a b c d e Smith, K. C.; Dworetsky, M. M. (1993), "Elemental Abundances in Normal Late B-Stars and Hgmn-Stars from Co-Added IUE Spectra - Part One - Iron Peak Elements", Astronomy and Astrophysics, 274 (2): 335, Bibcode:1993A&A...274..335S
- ^ a b Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785 , Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298
- ^ "tet Leo -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012年02月11日
- ^ "List of IAU-approved Star Names" . Retrieved 17 January 2023.
- ^ Netopil, M.; et al. (November 2008), "Chemically peculiar stars and their temperature calibration", Astronomy and Astrophysics, 491 (2): 545–554, arXiv:0809.5131 , Bibcode:2008A&A...491..545N, doi:10.1051/0004-6361:200810325, S2CID 14084961
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013年12月03日, retrieved 2012年01月16日
- ^ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. 48 (283). San Francisco, California: 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681 . S2CID 120743052.
- ^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the Solar System, Dover Books on Astronomy, vol. 2 (2nd ed.), Courier Dover Publications, p. 1067, ISBN 0-486-23568-8
- ^ "IAU Working Group on Star Names (WGSN)" . Retrieved 22 May 2016.
- ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
- ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010年08月19日 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived 2010年08月10日 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ^ "LacusCurtius • Allen's Star Names — Leo".