Mirach
Star in the constellation Andromeda / From Wikipedia, the free encyclopedia
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Mirach/ˈmaɪræk/,[14][15] Bayer designation Beta Andromedae, Latinized from β Andromedae, is a prominent star in the northern constellation of Andromeda. It is northeast of the Great Square of Pegasus and is potentially visible to all observers north of latitude 54° S. It is commonly used by stargazers to find the Andromeda Galaxy. The galaxy NGC 404, also known as Mirach's Ghost, is seven arcminutes away from Mirach.[16]
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Andromeda |
Right ascension | 01h 09m 43.91s[1] |
Declination | +35° 37′ 13.8″[1] |
Apparent magnitude (V) | 2.067[1] (2.01 to 2.10)[2] |
Characteristics | |
Evolutionary stage | Asymptotic giant branch[3] |
Spectral type | M0 III[4][5] |
U−B color index | +1.96[6] |
B−V color index | +1.57[6] |
V−R color index | 0.9[7] |
R−I color index | +1.00[8] |
Variable type | Semiregular[2] |
Astrometry | |
Radial velocity (Rv) | 0.06±0.13[9] km/s |
Proper motion (μ) | RA: 175.90[10] mas/yr Dec.: −112.20[10] mas/yr |
Parallax (π) | 16.52 ± 0.56 mas[10] |
Distance | 199.27±9.27 ly (61.12±2.84 pc)[1] |
Absolute magnitude (MV) | −1.76[11] |
Details[5] | |
Mass | 2.49[12][5] M☉ |
Radius | 86.4 R☉ |
Luminosity | 1,675 L☉ |
Surface gravity (log g) | 0.541 cgs |
Temperature | 3,802 K |
Metallicity [Fe/H] | −0.03 dex |
Rotation | <7900 d (<21.6 years) |
Rotational velocity (v sin i) | 6 km/s |
Other designations | |
Database references | |
SIMBAD | data |
This star has an apparent visual magnitude of around 2.07,[1] varying between 2.01 and 2.10,[2] which at times makes it the brightest star in the constellation. Based upon parallax measurements, it is roughly 197 light-years (60 parsecs) from the Sun.[10] Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight.[9] The star has a negligible radial velocity of 0.1 km/s,[9] but with a relatively large proper motion, traversing the celestial sphere at 0.208″·yr−1.[17]