Gamma Hydrae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 13h 18m 55.29719s |
| Declination | −23° 10′ 17.4514″ |
| Apparent magnitude (V) | +2.993 |
| Characteristics | |
| Evolutionary stage | horizontal branch |
| Spectral type | G8 III |
| U−B color index | +0.645 |
| B−V color index | +0.920 |
| Astrometry | |
| Radial velocity (Rv) | −5.4 km/s |
| Proper motion (μ) | RA: +68.99 mas/yr Dec.: −41.85 mas/yr |
| Parallax (π) | 24.37±0.15 mas |
| Distance | 133.8 ± 0.8 ly (41.0 ± 0.3 pc) |
| Absolute magnitude (MV) | −0.15 |
| Orbit | |
| Primary | A |
| Name | B |
| Semi-major axis (a) | 67.5±0.6 or 159±7 AU |
| Details | |
| A | |
| Mass | 2.90±0.29 M☉ |
| Radius | 12.47 ± 0.63 R☉ |
| Luminosity | 96.8+9.1 −8.3 L☉ |
| Surface gravity (log g) | 2.94±0.05 cgs |
| Temperature | 5,127±30 K |
| Metallicity [Fe/H] | +0.02±0.02 dex |
| Rotational velocity (v sin i) | 8 km/s |
| Age | 372 Myr |
| B | |
| Mass | 0.61+0.12 −0.14 M☉ |
| Other designations | |
| Naga, γ Hya, 46 Hya, NSV 6180, BD−22 3554, FK5 495, HD 115659, HIP 64962, HR 5020, SAO 181543 | |
| Database references | |
| SIMBAD | data |
Gamma Hydrae, officially named Naga, is a binary star in the equatorial constellation of Hydra. It has an apparent visual magnitude of 3.0, placing it second in brightness among the members of this generally faint constellation. Based upon parallax measurements made during the Hipparcos mission, this star is at a distance of around 133.8 light-years (41.0 parsecs) from Earth.