Beta Eridani

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β Eridani
Eridanus constellation map.svg
Red circle.svg

Location of β Eridani (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 05h 07m 50.98549s[1]
Declination −05° 05′ 11.2055″[1]
Apparent magnitude (V) 2.796[2]
Characteristics
Spectral type A3 III var[3]
U−B color index +0.124[2]
B−V color index +0.110[2]
R−I color index +0.08[4]
Astrometry
Radial velocity (Rv) –3.6[5] km/s
Proper motion (μ) RA: -82.82[1] mas/yr
Dec.: -75.39[1] mas/yr
Parallax (π) 36.50 ± 0.42[1] mas
Distance 89 ± 1 ly
(27.4 ± 0.3 pc)
Details
Mass 2.0[6] M☉
Radius 2.4[6] R☉
Luminosity 25[6] L☉
Surface gravity (log g) 3.58[5] cgs
Temperature 8,360,[7] 8,104[5] K
Metallicity [Fe/H] –0.4[8] dex
Rotational velocity (v sin i) 196[3] km/s
Other designations
Cursa/Kursa,[9] Dhalim,[10] β Eri, Beta Eridani, Beta Eri, 67 Eridani, 67 Eri, BD−05 1162, CCDM J05079-0506A, FK5 188, GC 6274, GJ 9175, HD 33111, HIP 23875, HR 1666, IDS 05030-0513 A, PPM 187729, SAO 131794, WDS 05078-0505A.[11]

Beta Eridani (Beta Eri, β Eridani, β Eri) is the second brightest star in the constellation of Eridanus, located in the northeast end of this constellation near the shared border with Orion. It has the traditional name Cursa.[4][7] 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]

Properties

β Eridani has a spectral type of A3 III,[3] with the III luminosity class indicating this is a giant star that has consumed the hydrogen at its core and evolved away from the main sequence. The effective temperature of the outer envelope is about 8,104 K,[5] which gives the star a white hue typical of A-type stars.[12] The projected rotational velocity is a rapid 196 km s−1,[3] compared to 2 km s−1 along the Sun's equator.[13] The star is known to vary in apparent visual magnitude, ranging between 2.72 and 2.80.[14] A particularly strong flare up was reported in 1985.[7][15]

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 though 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 120 arcseconds and a position angle of 148°.[16] It has the catalogue identifier CCDM J05079-0506B.[17]

Etymology

The term Cursa is derived from Al Kursiyy al Jauzah, "the Chair (or "Footstool") of the Central One". This is the name of star association consisting this star, along with λ Eri, ψ Eri and τ Ori.[10] According to a NASA catalogue of stars, Al Kursiyy al Jauzah was the title of three stars: β Eri is Cursa, ψ Eridani Al Kursiyy al Jauzah I, and λ Eridani Al Kursiyy al Jauzah II (excluding τ Orionis).[18]

In Chinese, 玉井 (Yù Jǐng), "the Jade Well", refers to an asterism consisting of β Eridani, λ Eridani, ψ Eridani and τ Orionis.[19] Consequently, β Eridani itself is known as "the third star of Jade Well" (玉井三 Yù Jǐng sān).[20] In older texts, Yu Jing was also spelt Yuh Tsing.[10]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 3.2 3.3 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 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.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ 6.0 6.1 6.2 Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 10.2 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ NSV 1841, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line September 17, 2008.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ BD-05 1162B -- Star in double system, database entry, SIMBAD. Accessed on line September 17, 2008.
  18. ↑ 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
  19. ↑ (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.
  20. ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
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