6 Hydrae
Star in the constellation Hydra
From Wikipedia, the free encyclopedia
6 Hydrae is a single[8] star in the equatorial constellation of Hydra, located 373 light-years away from the Sun.[2] It has the Bayer designation a Hydrae; 6 Hydrae is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.98.[1] It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s.[5] Eggen (1995) listed it as a proper motion candidate for membership in the IC 2391 supercluster.[9]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 08h 40m 01.47182s[2] |
| Declination | −12° 28′ 31.3433″[2] |
| Apparent magnitude (V) | 4.98[1] |
| Characteristics | |
| Evolutionary stage | red giant branch[3] |
| Spectral type | K3 III[4] |
| B−V color index | 1.415±0.001[1] |
| Astrometry | |
| Radial velocity (Rv) | −7.8±0.6[5] km/s |
| Proper motion (μ) | RA: −81.619[2] mas/yr Dec.: −1.646[2] mas/yr |
| Parallax (π) | 8.7394±0.1769 mas[2] |
| Distance | 373 ± 8 ly (114 ± 2 pc) |
| Absolute magnitude (MV) | −0.40[1] |
| Details | |
| Radius | 32.7+0.5 −2.6[2] R☉ |
| Luminosity | 267±6[2] L☉ |
| Surface gravity (log g) | 1.91[6] cgs |
| Temperature | 4,080+173 −30[2] K |
| Metallicity [Fe/H] | −0.21[6] dex |
| Other designations | |
| a Hya, 6 Hya, BD−11°2420, HD 73840, HIP 42509, HR 3431, SAO 154515[7] | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of K3 III,[4] which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. As a consequence, it has expanded to 33[2] times the radius of the Sun. The star is radiating 267[2] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,080 K.[2]