Alphard

This article is about the star. For the programming language, see Alphard (programming language). For the vehicle, see Toyota Alphard.
Alphard
Location of Alphard (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 09h 27m 35.2433s[1]
Declination −08° 39′ 30.969″[1]
Apparent magnitude (V) +2.00[2]
Characteristics
Evolutionary stage Giant star
Spectral type K3IIIa[3]
U−B color index +1.73[4]
B−V color index +1.45[3]
Astrometry
Radial velocity (Rv)−4.3[5] km/s
Proper motion (μ) RA: −14.49[1] mas/yr
Dec.: 33.25[1] mas/yr
Parallax (π)18.40 ± 0.78 mas[1]
Distance177 ± 8 ly
(54 ± 2 pc)
Absolute magnitude (MV)−1.743±0.032[3]
Details
Mass3.2±0.32[3] M☉
Radius55.9±2.4[6] R☉
Luminosity971+154
−133[3] L☉
Luminosity (visual, LV)426[3][a] L☉
Surface gravity (log g)1.77[6] cgs
Temperature4117±18[3] K
Metallicity [Fe/H]−0.12[6] dex
Rotation2,991 days[7]
Rotational velocity (v sin i)1.1[7] km/s
Age420±160[8] Myr
Other designations
Alphard, Alfard, Alphart, Kalbelaphard, Cor Hydrae, 30 Hydrae, HR 3748, BD−08°2680, HD 81797, SAO 136871, FK5 354, HIP 46390[9]
Database references
SIMBADdata

Alphard /ˈælfɑːrd/,[10] designated Alpha Hydrae (α Hydrae, abbreviated Alpha Hya, α Hya), is the brightest star in the constellation of Hydra. It is a single giant star, cooler than the Sun but larger and more luminous. It is about 177 light-years away.

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  10. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.


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