Nu Hydri

ν Hydri, Latinized as Nu Hydri, is a single^[10] star in the southern circumpolar constellation of Hydrus. It is orange-hued and faintly visible to the naked eye with an apparent visual magnitude of 4.76.^[2] This object is located approximately 331 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +3 km/s.^[1] It is a member of the Ursa Major Moving Group of stars that share a common motion through space.^[11]

Nu Hydri

Location of ν Hydri (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Hydrus
Right ascension	02h 50m 28.45915s[1]
Declination	−75° 04′ 00.9969″[1]
Apparent magnitude (V)	4.76[2]
Characteristics
Spectral type	K3III[3]
U−B color index	+1.56[4]
B−V color index	+1.33[4]
Astrometry
Radial velocity (Rv)	+3.09±0.16[1] km/s
Proper motion (μ)	RA: −33.392[1] mas/yr Dec.: −27.286[1] mas/yr
Parallax (π)	9.8538±0.1433 mas[1]
Distance	331 ± 5 ly (101 ± 1 pc)
Absolute magnitude (MV)	−0.33[2]
Details
Mass	3.5[5] or 1.79[6] M☉
Radius	21.23+3.23 −4.50[1] R☉
Luminosity	183.8±3.2[1] L☉
Surface gravity (log g)	3.30[7] cgs
Temperature	4,612+584 −315[1] K
Metallicity [Fe/H]	−1.52[7] dex
Rotation	50 d[5]
Rotational velocity (v sin i)	1.3[8] km/s
Age	2.38[6] Gyr
Other designations
ν Hyi, CPD−75°204, FK5 2199, GC 3463, HD 18293, HIP 13244, HR 872, SAO 255929[9]
Database references
SIMBAD	data

This is an aging giant star with a stellar classification of K3III.^[3] With the supply of hydrogen at its core exhausted, the star has expanded and cooled. At present it has 21^[1] times the girth of the Sun. It is 2.4^[6] billion years old with estimates of its mass ranging from 1.8^[6] to 3.5^[5] times the mass of the Sun. The star is radiating 184^[1] times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,612 K.^[1]