supergiant · M5Ib
Rasalgethi
Rasalgethi is a red supergiant (spectral type M5Ib) about 360 light-years away. With an apparent magnitude of 2.77 it is easy to see even from a city.
A huge red star at the head of Hercules.
Its light output is roughly 810 times that of the Sun (a rough estimate in visible light, calculated from brightness and distance).
From Germany (52° N) it rises and sets; it is best seen in the evening in June.
Key facts
- Distance
- ≈ 360 light-years
- Spectral type
- M5Ib (supergiant)
- Colour
- Red
- Apparent magnitude
- 2.77 mag
- Luminosity
- ≈ 810 × Sun
- Position
- Right ascension 17h 15m, declination 14.4°
More well-known stars
Data: Hipparcos / HYG catalogue (CC BY-SA 4.0). Luminosity and visibility are calculated estimates.