V Hydrae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 10h 51m 37.26159s |
| Declination | −21° 15′ 00.3339″ |
| Apparent magnitude (V) | 6.0 - 12.3 |
| Characteristics | |
| Spectral type | C6,3e-C7,5e(N6e) |
| B−V color index | +5.43 |
| Variable type | SRa |
| Astrometry | |
| Radial velocity (Rv) | −14.80 km/s |
| Proper motion (μ) | RA: −16.19 mas/yr Dec.: +2 mas/yr |
| Parallax (π) | 2.3095±0.1080 mas |
| Distance | 1,410 ± 70 ly (430 ± 20 pc) |
| Absolute magnitude (MV) | −3.5 to +1.8 |
| Orbit | |
| Period (P) | 17.45+0.34 −0.29 yr |
| Semi-major axis (a) | 11.2+1.2 −1.5 AU |
| Eccentricity (e) | 0.024+0.027 −0.017 |
| Inclination (i) | 37.7+2.2 −2.0° |
| Longitude of the node (Ω) | 159.7+43.0 −3.3° |
| Periastron epoch (T) | JD = 2,458,684+2,128 −2,582 |
| Argument of periastron (ω) (secondary) | 343+147 −122° |
| Details | |
| A | |
| Mass | 1.9±1.0 M☉ |
| Radius | 420–430 R☉ |
| Luminosity | 18,000 L☉ |
| Surface gravity (log g) | −0.5 cgs |
| Temperature | 2,650 K |
| Rotational velocity (v sin i) | 11 - 14 km/s |
| B | |
| Mass | 2.63+0.63 −0.69 M☉ |
| Radius | 1.5 R☉ |
| Temperature | 9,950 K |
| Other designations | |
| V Hya, BD−20°3283, HIP 53085, 2MASS J10513724-2115002, IRAS 10491-2059, WDS J10516-2115 | |
| Database references | |
| SIMBAD | data |
V Hydrae (V Hya) is a carbon star in the constellation Hydra. It is so-far the only star discovered in the Milky Way galaxy to have plasma ejections/eruptions on a grand scale that could be caused by its near, unseen companion.