Alpha Herculis
From Free net encyclopedia
Alpha Herculis (α Her / α Herculis) is a star in the constellation Hercules. It also has the traditional name Ras Algethi or Rasalgethi, and the Flamsteed designation 64 Herculis.
There are two components, α1 and α2, and α1 is a double star system with a primary massive red giant star and a closer companion.
The traditional name comes from Arabic Rasalgethi from Rās al-Jathi "head of the kneeling one".
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Physical and other characteristics
Ras Algethi is the 4th largest star known to us, circa 460 times greater than the Sun.
| Observation data | |
| Semiregular Variable, type SR c | |
| Right ascension (RA, α) (J2000,00) | 17 h 14 m 38.80 s |
| Declination (Dec, δ) (J2000,00) | +14° 23' 25.0" |
| Distance from Earth | 550 LY | (169 pc) |
| Visual brightness (V) | +3.1m to +3.9 | +5m to +7m |
| Absolute magnitude | |
| Physical characteristics | |
| Mean Diameter (dS = 1,392,000 km) | 560,000,000 km | ~ 402.3 dS 3.74 AU |
| Surface area | |
| Volume | |
| Mass | |
| Relative mass to the Sun (mS = 1.9891 × 1030 kg) | |
| Density | |
| Surface gravity | |
| Spectral type | M5 Ib-II (Red Super Giant) |
| Surface temperature | |
| Age | |
| Color (B-V) | (Orange-red | Bluish-green) |
| V-I | |
| Luminosity (LS = 3.827 × 1026 W) | |
| Orbital characteristics | |
| Period of rotation | |
| Period | |