Delta Hydri

Delta Hydri, Latinized from δ Hydri, is a single,^[7] white-hued star in the southern constellation of Hydrus. It is bright enough to be faintly visible to the naked eye with an apparent visual magnitude of 4.09.^[2] The distance to this star, based upon an annual parallax shift of 23.35 mas,^[1] is about 140 light years. It is moving away from the Sun with a radial velocity of +6 km/s.^[4]

δ Hydri

Location of δ Hydri (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Hydrus
Right ascension	02h 21m 44.94286s[1]
Declination	−68° 39′ 33.9038″[1]
Apparent magnitude (V)	4.09[2]
Characteristics
Spectral type	A2 V[3]
U−B color index	+0.05[2]
B−V color index	+0.03[2]
Astrometry
Radial velocity (Rv)	+6.00[4] km/s
Proper motion (μ)	RA: -49.95[1] mas/yr Dec.: +2.48[1] mas/yr
Parallax (π)	23.35±0.34 mas[1]
Distance	140 ± 2 ly (42.8 ± 0.6 pc)
Absolute magnitude (MV)	0.92[3]
Details
Mass	2.25[5] M☉
Radius	2.3[5] R☉
Luminosity	39.52[3] L☉
Surface gravity (log g)	3.98[6] cgs
Temperature	9,880±336[6] K
Metallicity [Fe/H]	+0.12[3] dex
Rotational velocity (v sin i)	162[6] km/s
Age	209[6] Myr
Other designations
δ Hyi, CPD−69°113, FK5 1065, GC 2872, HD 15008, HIP 11001, HR 705, SAO 248545
Database references
SIMBAD	data

This is an ordinary A-type main-sequence star with a stellar classification of A2 V^[3] It is about 209 million years old and has a high rate of spin, showing a projected rotational velocity of 162 km/s.^[6] This is giving the star an oblate shape with an equatorial bulge that is 7% larger than the polar radius.^[8] The star has 2.25 times the mass of the Sun and 2.3 times the Sun's radius.^[5] It is radiating 39.5^[3] times the Sun's luminosity from its photosphere at an effective temperature of around 9.880.^[6] Delta Hydri has been checked for an infrared excess, but none was found.^[7]