Alphard (Alpha Hydrae)


Hydra and environs. Map © 2003 Torsten Bronge.

Alphard (Alpha Hydrae) is the brightest star in the constellation Hydra, made more noticeable by being in a fairly barren region of sky to the southwest of Regulus. Its Arabic name means "the solitary one."


Alphard is an orange giant and mild barium star with a companion that, before it became a white dwarf, contaminated its partner with the by-products of nuclear fusion that had been dredged to its surface.


visual magnitude 1.99
absolute magnitude -1.69
spectral type K3II-III
surface temperature 4,000 K
luminosity 400 Lsun
distance 177 light-years (54 pc)
position RA 09h 27m 35.2s,
Dec -08° 39' 31"
other designations Alfard, Alphart, Kalbelaphard,
Cor Hydrae, 30 Hydrae,
HR 3748, BD -08°2680, HD 81797,
SAO 136871, FK5 354, HIP 46390