Xi Hydrae, Latinised from ξ Hydrae, is a solitary[9] star in the equatorial constellation of Hydra. It was also given the Flamsteed designation 19 Crateris. This magnitude 3.54[2] star is situated 130 light-years from Earth and has a radius about 10 times that of the Sun. It is radiating 58 times as much luminosity as the Sun.[6]
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Hydra |
Right ascension | 11h 33m 00.11505s[1] |
Declination | −31° 51′ 27.4435″[1] |
Apparent magnitude (V) | 3.54[2] |
Characteristics | |
Spectral type | G7 III[2] |
Astrometry | |
Radial velocity (Rv) | −4.90±0.30[3] km/s |
Proper motion (μ) | RA: −209.62[1] mas/yr Dec.: −40.84[1] mas/yr |
Parallax (π) | 25.16 ± 0.16 mas[1] |
Distance | 129.6 ± 0.8 ly (39.7 ± 0.3 pc) |
Absolute magnitude (MV) | +0.54[4] |
Details | |
Mass | 2.94±0.15[5] M☉ |
Radius | 10.2±0.1[6] R☉ |
Luminosity | 57.65±2.39[6] L☉ |
Surface gravity (log g) | 2.87±0.02[5] cgs |
Temperature | 5,044±40[5] K |
Metallicity [Fe/H] | +0.16±0.20[5] dex |
Rotational velocity (v sin i) | 2.7[6] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Flamsteed gave Xi Hydrae the designation 19 Crateris. He included a number of stars now within the IAU boundaries of Hydra as part of a Hydra & Crater constellation overlapping parts of both modern constellations.[10]
The star Xi Hydrae is particularly interesting in the field of asteroseismology since it shows solar-like oscillations. Multiple frequency oscillations are found with periods between 2.0 and 5.5 hours.[11]
Xi Hydrae has left the main sequence, having exhausted the supply of hydrogen in its core. Its spectrum is that of a red giant. Modelling its physical properties against theoretical evolutionary tracks shows that it has just reached the foot of the red giant branch for a star with an initial mass around 3 M☉. This puts its age at about 510 myr.[12]