Ras Algethi
Ras Algethi (Arabic Rasalgethi from Ra`s al-Jathi a Head of the kneeling one) (α 1 Herculis | 64 Herculis) is a double star system with a primary massive red giant star and a closer companion.
Ras Algheti is the 4th largest star known to us, circa 720 times greater than the Sun.
Physical and other characteristics
| 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 J s-1) | |
| Orbital characteristics | |
| Period of rotation | |
| Period | |
