main-sequence star · B8V
Algol
Algol is a blue main-sequence star (spectral type B8V) about 90 light-years away. With an apparent magnitude of 2.09 it is easy to see even from a city.
The "Demon Star": every 2 days 21 hours it becomes clearly dimmer for a few hours.
Its light output is roughly 90 times that of the Sun (a rough estimate in visible light, calculated from brightness and distance).
From Germany (52° N) it never sets: it stays above the horizon all year.
Key facts
- Distance
- ≈ 90 light-years
- Spectral type
- B8V (main-sequence star)
- Colour
- Blue
- Apparent magnitude
- 2.09 mag
- Luminosity
- ≈ 90 × Sun
- Position
- Right ascension 3h 8m, declination 41°
More well-known stars
Data: Hipparcos / HYG catalogue (CC BY-SA 4.0). Luminosity and visibility are calculated estimates.