Gamma Hydrae

γ Hydrae
Location of γ Hydrae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hydra
Right ascension 13h 18m 55.29719s[1]
Declination –23° 10′ 17.4514″[1]
Apparent magnitude (V) +2.993[2]
Characteristics
Spectral type G8 III[3]
U−B color index +0.645[2]
B−V color index +0.920[2]
Astrometry
Radial velocity (Rv)–5.4[4] km/s
Proper motion (μ) RA: +68.99[1] mas/yr
Dec.: –41.85[1] mas/yr
Parallax (π)24.37 ± 0.15 mas[1]
Distance133.8 ± 0.8 ly
(41.0 ± 0.3 pc)
Absolute magnitude (MV)–0.15[3]
Details
A
Mass2.94[3] M☉
Radius16±3[5] R☉
Luminosity115[3] L☉
Surface gravity (log g)3.02[6] cgs
Temperature5,087[6] K
Metallicity [Fe/H]–0.06[6] dex
Rotational velocity (v sin i)8[7] km/s
Age372[3] Myr
B
Mass0.61+0.12
−0.14[8] M☉
Orbit[8]
PrimaryA
CompanionB
Semi-major axis (a)67.5±0.6 or 159±7 AU
Other designations
46 Hydrae, BD–22 3554, FK5 495, HD 115659, HIP 64962, HR 5020, NSV 6180, SAO 181543.[9]
Database references
SIMBADdata

Gamma Hydrae (γ Hya, γ Hydrae) is a binary star in the equatorial constellation of Hydra. It has an apparent visual magnitude of 3.0,[2] placing it second in brightness among the members of this generally faint constellation. Based upon parallax measurements made during the Hipparcos mission, this star is at a distance of around 133.8 light-years (41.0 parsecs) from Earth.[1]

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