Beta Corvi or β Corvi, officially named Kraz (/ˈkræz/),[11] is the second-brightest star in the southern constellation of Corvus with an apparent visual magnitude of 2.647.[2] Based on parallax measurements obtained during the Hipparcos mission, it is about 146 light-years (45 parsecs) distant from the Sun.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corvus |
| Right ascension | 12h 34m 23.23484s[1] |
| Declination | −23° 23′ 48.3374″[1] |
| Apparent magnitude (V) | 2.647[2] |
| Characteristics | |
| Spectral type | G5 II[3] |
| U−B color index | +0.586[2] |
| B−V color index | +0.898[2] |
| R−I color index | +0.44[4] |
| Astrometry | |
| Radial velocity (Rv) | −7.6[5] km/s |
| Proper motion (μ) | RA: +1.11[1] mas/yr Dec.: −56.56[1] mas/yr |
| Parallax (π) | 22.39 ± 0.18 mas[1] |
| Distance | 146 ± 1 ly (44.7 ± 0.4 pc) |
| Absolute magnitude (MV) | –0.61[6] |
| Details | |
| Mass | 3.342±0.077[7] M☉ |
| Radius | 15.841±0.72[7] R☉ |
| Luminosity | 164[8] L☉ |
| Surface gravity (log g) | 2.86[7] cgs |
| Temperature | 5,354[7] K |
| Metallicity [Fe/H] | 0.12±0.03[7] dex |
| Rotational velocity (v sin i) | 8[9] km/s |
| Age | 294±18[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Nomenclature
β Corvi (Latinised to Beta Corvi) is the star's Bayer designation.
In a 1951 publication, Atlas Coeli (Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář, it bore the name Kraz, whose origin and meaning remain unknown.[12][13][14] In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN approved the name Kraz for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.[11]
In Chinese, 軫宿 (Zhěn Sù), meaning Chariot (asterism), refers to an asterism consisting of Beta, Gamma, Epsilon and Delta Corvi.[16] Consequently, Beta Corvi itself is known as 軫宿四 (Zhěn Sù sì, English: the Fourth Star of Chariot).[17]
Properties
Beta Corvi has about 3.3 times the Sun's mass and is roughly 300 million years old,[7] which is old enough for a star of this mass to consume the hydrogen at its core and evolve away from the main sequence. The stellar classification is G5 II,[3] with the luminosity class of 'II' indicating this is a bright giant. The effective temperature of the star's outer envelope is about 5,350 K,[7] which produces a yellow hue common to G-type stars.[18]
Currently, Beta Corvi has expanded to 15.8 times the Sun's size[7] and is emitting about 164 times the luminosity of the Sun.[8] The abundance of elements other than hydrogen or helium, what astronomers term metallicity, is 1.32 times that of the Sun.[7][a]
This is a variable star that ranges in apparent visual magnitude from a low of 2.66 to a high of 2.60.[19]
See also
- List of stars in Corvus
- Beta Leporis, another bright giant star with similar size and spectral type