hip-13775

Its story

21 Persei is a variable star that pulses slowly some three hundred and twenty light-years away, within the hero who brandishes Medusa's head. Its B type places it among the young and hot, and its brightness shifts in subtle rhythms that only patient photometry can capture. In Perseus, neighbour to famous Algol —the Gorgon's eye that blinks every three days—, it is not the only star that breathes with light.