Upsilon Ursae Majoris, Latinized from υUrsae Majoris, is a binary star[12] in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of +3.79.[4] Based upon an annual parallax shift of 13.24mas,[1] it is located roughly 246light-years from the Sun.
A light curve for Upsilon Ursae Majoris, plotted from TESS data[13]
Binary star in the constellation Ursa Major
Upsilon Ursae Majoris
Location of υ Ursae Majoris (circled)
Observation data Epoch J2000.0Equinox J2000.0 (ICRS)
The primary member of the system, component A, is an F-type subgiant star. It is a Delta Scuti variable[8] with a period of 0.1327day and an amplitude of 0.050 magnitude.[14] With an estimated age of 1.168[7] billion years, it is spinning rapidly with a projected rotational velocity of 124.2km/s[10] and a rotation period of 1.2days.[8] The star has about 1.57[7] times the mass of the Sun and 2.79[8] times the Sun's radius. (De Rosa and colleagues give a mass estimate of 2.2[3] times the Sun's mass.) It is radiating around 29.5[9] times the solar luminosity from its outer atmosphere at an effective temperature of 7,211K.[7]
The companion, component B, is a magnitude +11.0 star.[12] As of 2008, it has an angular separation of 11.78arcseconds along a position angle of 295.4°. This corresponds to a projected separation of 419.8AU.[3] It has a mass around 40% that of the Sun.[3]
Naming
With τ, h, φ, θ, e and f, it composed the Arabic asterism Sarīr Banāt al-Na'sh, the Throne of the daughters of Na'sh, and Al-Haud, the Pond.[15] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al-Haud were the title for seven stars: f as Alhaud I, τ as Alhaud II, e as Alhaud III, h as Alhaud IV, θ as Alhaud V, this star (υ) as Alhaud VI and φ as Alhaud VII .[16]
In Chinese, 文昌 (Wén Chāng), meaning Administrative Center, refers to an asterism consisting of υ Ursae Majoris, φ Ursae Majoris, θ Ursae Majoris, 15 Ursae Majoris and 18 Ursae Majoris. Consequently, the Chinese name for υ Ursae Majoris itself is 文昌一 (Wén Chāng yī, English: the first Star of Administrative Center.).[17]
Samus, N. N.; Durlevich, O. V.; etal. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.
De Rosa, R. J.; etal. (2013), "The VAST Survey – III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932, S2CID88503488.
Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
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, S2CID59451347, A61.
Ammler-von Eiff, Matthias; Reiners, Ansgar (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID53666672.
David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID33401607.
Korzennik, S. G.; etal. (April 1995), "Nightly variations of nonradial oscillations in the Delta Scuti star upsilon Ursae Majoris", Astrophysical Journal, Part 2, 443 (1): L25–L28, Bibcode:1995ApJ...443L..25K, doi:10.1086/187827.
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