Delta Hydrae
Delta Hydrae, Latinized from δ Hydrae, is a double star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 4.146. Based upon an annual parallax shift of 20.34 mas, it is located about 160 light years from the Sun.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Hydra |
| Right ascension | 08h 37m 39.36627s |
| Declination | +05° 42′ 13.6057″ |
| Apparent magnitude (V) | 4.146 |
| Characteristics | |
| Spectral type | A1 Vnn |
| U−B color index | +0.003 |
| B−V color index | +0.008 |
| Astrometry | |
| Radial velocity (Rv) | 4.10 km/s |
| Proper motion (μ) | RA: −70.19 mas/yr Dec.: −7.90 mas/yr |
| Parallax (π) | 20.34 ± 0.63 mas |
| Distance | 160 ± 5 ly (49 ± 2 pc) |
| Absolute magnitude (MV) | +0.68 |
| Details | |
| Mass | 2.88 M☉ |
| Radius | 2.7 R☉ |
| Luminosity | 42.7 L☉ |
| Temperature | 11,055±376 K |
| Rotational velocity (v sin i) | 285 km/s |
| Age | 244 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a double star with an angular separation of 2.6±0.1 arc second along a position angle of 265.1°±1.0°, as of 2003. The brighter component is an A-type main sequence star with a stellar classification of A1 Vnn. It is spinning rapidly with a projected rotational velocity of 285 km/s. This is giving the star an oblate shape with an equatorial bulge that is 20% larger than the polar radius. It has an estimated 2.88 times the mass of the Sun and 2.7 times the Sun's radius. The star is about 244 million years old and it radiates 42.7 times the solar luminosity from its outer atmosphere at an effective temperature of 11,055 K.
The companion has a visual magnitude of 11.15. X-ray emissions have been detected from this location in space, which may be coming from a companion star.