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Achernar

 
Dictionary: A·cher·nar   (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.]


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Achernar (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
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Achernar

The position of Achernar.
Observation data
Epoch J2000      Equinox 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
α Eri, 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.

Achernar is a bright, blue, B-type star of six to eight solar masses lying approximately 144 light-years (44 pc) away. Although classified as a main-sequence (dwarf) star, it is about 3,000 times more luminous than the Sun. Achernar is in the deep southern sky and never rises above 33°N. Achernar is best seen from the southern hemisphere in November; it is circumpolar below 33°S.

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.

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

External links

Coordinates: Sky map 01h 37m 42.8s, −57° 14′ 12″


 
 
Learn More
eridanus
Achernar Island
Mount Achernar

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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