About HD 35921
HD 35921 is an epic variable star. It lies about 994.4 light-years from Earth, sits in the constellation Aur, shines at apparent magnitude 6.78 and has spectral type O9.5III.
Its spectrum reads O9.5III — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.