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A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun.  Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape.  Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>   

A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun.  Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape.  Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>   

Achernar is still young enough, being only a couple hundred million years old, to still be fusing [[hydrogen]] into [[helium]] in its core.  It will burn through its core fuel quickly however, and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

There are no known substaller companions to Achernar.  For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]].  At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

There are no known substaller companions to Achernar.  For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]].  At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

 

People who believe in an old universe also believe Achernar is a couple hundred million years old, according to them, young enough to still be fusing [[hydrogen]] into [[helium]] in its core.  They think it will burn through its core fuel quickly however,  and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

[[Category:Astronomy]]

[[Category:Astronomy]]