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Achernar

  (ā'kər-när') pronunciation
Achernar
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n.

A star in the constellation Eridanus that is one of the brightest stars in the sky and is 114 light-years from Earth.

[From Arabic ’ahīr an-nahr, the end of the river (referring to the star's position in the constellation Eridanus) : ’ahīr, last, end + al-, the + nahr, river.]


 
 
(ā'kərnär') , brightest star in the constellation Eridanus; Bayer designation α Eridani; 1992 position R.A. 1h37.4m, Dec. −57°16′. A bluish-white white star with apparent magnitude 0.51, it is one of the 10 brightest stars in the entire sky. Its distance is about 120 light-years, and its luminosity about 600 times that of the sun. Achernar is of spectral class B5 V. Its name is from the Arabic meaning “end of the river [Eridanus].”


 
Wikipedia: Achernar
Achernar
Position_Alpha_Eri.png
The position of Achernar.
Observation data
Epoch J2000
Constellation Eridanus
Right ascension 01h 37m 42.8s
Declination −57° 14' 12"
Apparent magnitude (V) 0.50
Characteristics
Spectral type B3 Vpe
U-B color index −0.66
B-V color index −0.20
Variable type Lambda Eridani
Astrometry
Radial velocity (Rv) 16 km/s
Proper motion (μ) RA: 88.02 mas/yr
Dec.: −40.08 mas/yr
Parallax (π) 022.68 ± 0.57 mas
Distance 144 ± 4 ly
(44 ± 1 pc)
Absolute magnitude (MV) −2.77
Details
Mass 6–8 M
Radius ~10 R
Luminosity 3,311(bolometric) L
Temperature 14,510 K
Rotation 225–300 km/s
Age 1–5 × 108 years
Other designations
Alpha Eridani, α Eridani, HR 472, CD -57°334, HD 10144, SAO 232481, FK5 54, HIP 7588.

Achernar (α Eri / α Eridani / Alpha Eridani), sometimes spelled Achenar, is the brightest star in the constellation Eridanus and the eighth brightest star in the nighttime sky. It lies at the southern tip of the constellation.

The extreme rotation speed has flattened Achernar.
Enlarge
The extreme rotation speed has flattened Achernar.

Achernar is a bright blue star of six to eight solar masses. Although classified as a main sequence (dwarf) star, it is thousands of times brighter than the Sun. It is visible in the southern part of the night sky. It remains permanently below the horizon from many densely populated portions of Earth's northern hemisphere. From those Southern hemisphere countries from which it can be seen best, it is particularly conspicuous through being highest in the night sky in November when most other bright southern stars are skirting the horizon.

Until about March 2000, Achernar and Fomalhaut were the two first magnitude stars furthest in angular distance from any other first magnitude star in the celestial sphere. Antares, in the constellation of Scorpius, is now the most isolated first magnitude star.

It is the least spherical star in the Milky Way studied to date. Achernar spins so rapidly that its equatorial diameter is more than 50% greater than its polar diameter.

It is approximately 144 light years from the Solar System.

The name comes from the Arabic آخر النهر ākhir an-nahr "river's end".

It is known as 水委一 (Shuǐwěiyī, the First Star of the Crooked Running Water) in Chinese.

Fiction

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Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Achernar" Read more

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