Mu Andromedae
Mu Andromedae (Mu And, μ Andromedae, μ And) is the Bayer designation for a star in the northern constellation of Andromeda. It has an apparent visual magnitude of 3.87, making it readily visible to the naked eye. Based upon parallax measurements, it is approximately 130 light-years (40 parsecs) from Earth. In the constellation, the star is situated about halfway between the bright star Mirach to the southwest and the Andromeda Galaxy (M31) to the northeast.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 56m 45.21211s |
| Declination | +38° 29′ 57.6380″ |
| Apparent magnitude (V) | 3.87 |
| Characteristics | |
| Spectral type | A5 V |
| U−B color index | +0.15 |
| B−V color index | +0.12 |
| Astrometry | |
| Radial velocity (Rv) | +7.6 km/s |
| Proper motion (μ) | RA: +153.48 mas/yr Dec.: +36.49 mas/yr |
| Parallax (π) | 25.14 ± 0.86 mas |
| Distance | 130 ± 4 ly (40 ± 1 pc) |
| Absolute magnitude (MV) | +0.86 |
| Orbit | |
| Period (P) | 550.7 ± 0.2 d |
| Semi-major axis (a) | 46.66 ± 0.06 mas |
| Eccentricity (e) | 0.8405 ± 0.0009 |
| Inclination (i) | 52.5 ± 0.3° |
| Longitude of the node (Ω) | −17.6 ± 0.2° |
| Periastron epoch (T) | 55765.45 ± 0.04 MJD |
| Argument of periastron (ω) (secondary) | 168.9 ± 0.3° |
| Semi-amplitude (K1) (primary) | 11.1 ± 0.5 km/s |
| Details | |
| Mass | 2.0 M☉ |
| Radius | 2.4 R☉ |
| Luminosity | 21 L☉ |
| Surface gravity (log g) | 3.99 cgs |
| Temperature | 7,959 K |
| Metallicity [Fe/H] | +0.03 dex |
| Rotational velocity (v sin i) | 75 km/s |
| Age | 600 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of this star matches a stellar classification of A5 V, indicating that it is an A-type main sequence star. It has double the mass of the Sun and 2.4 times the Sun's radius. The star is radiating about 21 times the luminosity of the Sun from its outer envelope at an effective temperature of 7,959 K, giving it the characteristic white glow of an A-type star. It is estimated to be about 600 million years old, with a relatively high projected rotational velocity of 75 km/s. Mu Andromedae has recently been found to be a binary system. The two stars orbit each other every 550.7 days.