Changes

[[Image:Position Alpha Eri.png|thumb|right|154px|Location of Achernar in the constellation of Eridanus, as indicated by the pink arrow.]]

| constellation  =[[Eridanus]]

| magnitude      =Absolute Mag: -2.27<br/> Apparent Mag:0.50

| redshift        =

| radvelocity    =16 km/s

| propmotion      =RA: 87.00 ±0.58 mas/yr<br/>Dec.: −38.24 ±0.50 mas/yr

| parallax        =023.39 ±0.57  mas

'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky.  The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude.  South of 33 degrees south latitude, the star is [[circumpolar]].

'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky.  The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude.  South of 33 degrees south latitude, the star is [[circumpolar]].

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away.  The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref>  The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity.  Surface temperature estimates range from 14,500 to 19,300 K.

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away.  The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref>  The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity.  Surface temperature estimates range from 14,500 to 19,300 K.

 

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>