BetaEridani (βEridani, abbreviated BetaEri, βEri), formally named Cursa/ˈkɜːrsə/,[14] is the second-brightest star in the constellation of Eridanus, located in the northeast end of this constellation near the shared border with Orion. The apparent visual magnitude of this star is 2.796,[2] so it can be viewed with the naked eye in dark skies. Parallax measurements yield an estimated distance of about 89 light-years (27 parsecs) from the Earth.[1]
β Eridani is the bright star towards the top (north). The brightest star, towards lower left, is Rigel. In between is the reflection nebulaIC 2118.
Beta Eridani is the star's Bayer designation. It has the traditional name Cursa[4][9] derived from Al Kursiyy al Jauzah, "the Chair (or "Footstool") of the Central One". This is the name of the star association consisting of this star along with Lambda Eridani, Psi Eridani and Tau Orionis.[12]
According to a NASA catalogue of stars, Al Kursiyy al Jauzah was the title of three stars: β Eri is Cursa, Psi EridaniAl Kursiyy al Jauzah I, and Lambda EridaniAl Kursiyy al Jauzah II (excluding Tau Orionis).[15]
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[17] included a table of the first two batches of names approved by the WGSN; which included Cursa for this star.
In Chinese, 玉井 (Yù Jǐng), "the Jade Well", refers to an asterism consisting of β Eridani, λ Eridani, ψ Eridani and τ Orionis.[18] Consequently, the Chinese name for β Eridani itself is "the third star of Jade Well" (玉井三Yù Jǐng sān).[19]
In older texts, Yu Jing was also spelt Yuh Tsing.[12]
Properties
βEridani has a spectral type of A3III,[3] with the luminosity class III indicating that this is a giant star which has consumed the hydrogen at its core and evolved away from the main sequence. The effective temperature of the outer envelope is about 8,104K,[5] which gives the star a white hue typical of A-type stars.[20] The projected rotational velocity is a rapid 196 km s−1,[3] compared to 2 km s−1 along the Sun's equator.[21] The star is known to vary in apparent visual magnitude, ranging between 2.72 and 2.80.[22] A particularly strong flare up was reported in 1985.[9][23]
The location and trajectory of this star suggest that it is a member of the Ursa Major supergroup, an association of stars that share a common origin and motion through space. However, its photometric properties indicate that it may instead be an interloper.[5] Beta Eridani has an optical companion star with an apparent magnitude 10.90 at an angular separation of 120arcseconds and a position angle of 148°.[24] It has the catalogue identifier CCDM J05079-0506B.[25]
Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars, 8: 59, Bibcode:1984SAAOC...8...59C
HR 1666, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 17, 2008.
Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M
Kaler, James B., "Cursa (Beta Eridani)", Stars, University of Illinois, retrieved 2012-01-10
Moore, Patrick (2006), The amateur astronomer, Patrick Moore's Practical Astronomy Series (12thed.), Birkhäuser, p.200, ISBN1-85233-878-4
Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprinted.), New York, NY: Dover Publications Inc, p.218, ISBN0-486-21079-0, retrieved 2010-12-12
(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, ISBN978-986-7332-25-7.
(in Chinese)香港太空館 - 研究資源 - 亮星中英對照表Archived 2009-09-29 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
"The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
Brunner, B. H. (June 1985), "A Flare of Beta-Eridani", Sky and Telescope, 69 (6): 484, Bibcode:1985S&T....69R.484B
Mason, B. D.; Wycoff, G. L.; Hartkopf, W. I.; Douglass, G. G.; Worley, C. E. (November 2011), "The Washington Visual Double Star Catalog (Mason+ 2001-2011)", VizieR On-line Data Catalog: B/wds. Originally Published in: 2001AJ....122.3466M, vol.1, Bibcode:2011yCat....102026M
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