Algol
Blue-white eclipsing binary · Beta Persei
The Demon Star; prototype eclipsing binary that visibly dims every 2.87 days
Algol, the Demon Star in Perseus, is the prototype of the eclipsing binaries: every 2.87 days a dimmer companion passes in front of the bright star and its brightness visibly drops by more than a full magnitude before recovering. This regular winking, noticeable to the naked eye, may be why ancient cultures linked it to an ominous, blinking eye.
Illustration generated from temperature, not a photograph
3.2 ☉
mass (the Sun = 1)
182 ×
as bright as the Sun
13,000 K
surface · blue-white star
3 R☉
radius (the Sun = 1)
93 ly
from Earth
2.1
apparent magnitude
It pours out about 182 times the Sun’s light. Its light has been travelling 93 years to reach us, so you see Algol as it was 93 years ago.
Source · View on Wikidata
It lives in
Milky Way
Barred spiral galaxy.
Other notable stars in Milky Way
Eta CarinaeLuminous blue variableAlnilamBlue supergiantVY Canis MajorisRed hypergiantAlnitakHot blue supergiantDenebBlue-white supergiantMintakaHot blue giant multiple star
Stars of similar brightness
ArcturusOrange giant215 ×RegulusBlue-white main-sequence star341 ×AldebaranOrange giant439 ×VegaBlue-white main-sequence star40 ×AlphardOrange giant971 ×MizarBlue-white multiple star33 ×
Worlds in the same direction on the sky→