Delta Hydrae
Delta Hydrae, Latinized from δ Hydrae, is a triple star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.146.[2] Based upon an annual parallax shift of 20.34 mas, it is located about 160 light years distant.
Characteristics
This is a hierarchical triple system. δ Hydrae Aa and δ Hydrae Ab form a close binary system with an orbital separation of 0.9 astronomical units, taking about 200 days to complete an orbit.[7] The outer companion, δ Hydrae B, has an angular separation of 2.6±0.1 arc second from the Aa–Ab pair, along a position angle of 265.1°±1.0°, as of 2003.[6] At the system's distance, this separation translates in a physical projected separation of 147 AU.[7]
The brighter component, δ Hydrae Aa, is an A-type main sequence star with a stellar classification of A1 Vnn.[3] It is spinning rapidly with a projected rotational velocity of 285 km/s. This is giving the star an oblate shape with an equatorial bulge that is 20% larger than the polar radius.[3] It has an estimated 2.43 times the mass of the Sun and 3.1 times the Sun's radius.[7] The star radiates 42.7 times the solar luminosity from its photosphere[8] at an effective temperature of 8,995 K.[7]
Its inner companion, δ Hydrae Ab, is a red dwarf star, with 0.58 times the mass, 0.54 times the Sun's radius, and an effective temperature of 3,973 K. It may form a common envelope system when the primary evolve into a red giant.[7]
The outer companion has a visual magnitude of 11.15.[10] X-ray emissions have been detected from this location in space, which may be coming from a companion star.[6]
Name and etymology
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Lisan al Shudja, which was translated into Latin as Lingua Hydri, meaning the snake's tongue.[11] This star, along with ε Hya, ζ Hya, η Hya, ρ Hya and σ Hya (Minchir), were Ulugh Beg's Min al Azʽal, "Belonging to the Uninhabited Spot".[12]
According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Min al Azʽal or Minazal were the title for five stars: δ Hya as Minazal I, η Hya as Minazal II, ε Hya as Minazal III, ρ Hya as Minazal IV and ζ Hya as Minazal V (exclude σ Hya)[13]
In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Willow (asterism), refers to an asterism consisting of δ Hydrae, σ Hydrae, η Hydrae, ρ Hydrae, ε Hydrae, ζ Hydrae, ω Hydrae and θ Hydrae[14] Consequently, δ Hydrae itself is known as Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[15]
The people of Groote Eylandt called Unwala, "The Crab", for the star cluster including this star, ε Hya (Ashlesha), ζ Hya, η Hya, ρ Hya and σ Hya (Minchir).[16]
See also
- Lambda Muscae, another A star with two low-mass companions
References
- ^ a b c d e Page Module:Citation/CS1/styles.css has no content.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 c d Page Module:Citation/CS1/styles.css has no content.Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars, 8: 59, Bibcode:1984SAAOC...8...59C.
- ^ a b c d Page Module:Citation/CS1/styles.css has no content.Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1) 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
- ^ Page Module:Citation/CS1/styles.css has no content.de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
- ^ Page Module:Citation/CS1/styles.css has no content.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 Page Module:Citation/CS1/styles.css has no content.De Rosa, R. J.; et al. (July 2011), "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars", Monthly Notices of the Royal Astronomical Society, 415 (1): 854–866, arXiv:1103.4363, Bibcode:2011MNRAS.415..854D, doi:10.1111/j.1365-2966.2011.18765.x, S2CID 84181878.
- ^ a b c d e f g h Page Module:Citation/CS1/styles.css has no content.Waisberg, Idel; Klein, Ygal; Katz, Boaz (April 2023), "Discovery of a 0.58M☉, 0.9 au Companion to HIP 42313 = δ Hya", Research Notes of the American Astronomical Society, 7 (4): 65, Bibcode:2023RNAAS...7...65W, doi:10.3847/2515-5172/accb5c, ISSN 2515-5172.
- ^ a b Page Module:Citation/CS1/styles.css has no content.McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- ^ Page Module:Citation/CS1/styles.css has no content."* del Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-03.
{{cite web}}: Invalid|mode=Script error: No such module "Citation mode".(help) - ^ Page Module:Citation/CS1/styles.css has no content.Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
- ^ Page Module:Citation/CS1/styles.css has no content.Knobel, E. B. (June 1895), "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket", Monthly Notices of the Royal Astronomical Society, 55: 429, Bibcode:1895MNRAS..55..429K, doi:10.1093/mnras/55.8.429.
- ^ Page Module:Citation/CS1/styles.css has no content.Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York: Dover Publications Inc, p. 249, ISBN 0-486-21079-0, retrieved 2010-12-12.
{{citation}}: ISBN / Date incompatibility (help) - ^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
- ^ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
- ^ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 28 日 Script error: No such module "webarchive".
- ^ Helaine Selin, ed., Encyclopaedia of the history of science, technology, and medicine in non-western cultures, Dordrecht, Kluwer Academic Publishers, 1997, p.105.
External links
- Page Module:Citation/CS1/styles.css has no content.Kaler, James B. (April 13, 2012), "Delta Hydrae", STARS, University of Illinois, retrieved 2017-01-03.
