Mirach
Location of Mirach (circled) |
Observation data
Epoch J2000.0 Equinox J2000.0 (ICRS) |
| Constellation |
Andromeda |
|
| Right ascension |
01h 09m 43.91s |
| Declination |
+35° 37′ 13.8″ |
| Apparent magnitude (V) |
2.067 (2.01 to 2.10) |
| Characteristics |
| Evolutionary stage |
Asymptotic giant branch |
| Spectral type |
M0 III |
|
|
|
|
|
|
|
|
| U−B color index |
+1.96 |
| B−V color index |
+1.57 |
| V−R color index |
0.9 |
| R−I color index |
+1.00 |
|
|
| Variable type |
Semiregular |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Astrometry |
|---|
|
|---|
| Radial velocity (Rv) | 0.06±0.13 km/s |
| Proper motion (μ) | RA: 175.90 mas/yr
Dec.: −112.20 mas/yr |
| Parallax (π) | 16.52±0.56 mas |
| Distance | 197 ± 7 ly
(61 ± 2 pc) |
| Absolute magnitude (MV) | −1.76 |
|
|---|
| Details |
|---|
|
|---|
| Mass | 2.49 M☉ |
| Radius | 86.4 R☉ |
| Luminosity | 1,675 L☉ |
| Surface gravity (log g) | 0.91±0.10 cgs |
| Temperature | 3,762±40 K |
| Metallicity [Fe/H] | −0.46±0.03 dex |
| Rotation | <7900 d (<21.6 years) |
| Rotational velocity (v sin i) | 6 km/s |
|
|---|
| Other designations |
|---|
| Mirach, Merach, Mirac, Mizar, β And, Beta Andromedae, Beta And, 43 Andromedae, 43 And, BD+34°198, FK5 42, GJ 53.3, 9044, HD 6860, HIP 5447, HR 337, SAO 54471, PPM 66010, WDS 01097+3537A, LTT 10420, NLTT 3848 |
| Database references |
|---|
| SIMBAD | data |
Mirach is a prominent star in the northern constellation of Andromeda. It is pronounced and has the Bayer designation Beta Andromedae, which is Latinized from β Andromedae. This star is positioned 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.
This star has an apparent visual magnitude of around 2.07, varying between 2.01 and 2.10, 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 Solar System. Its apparent magnitude is reduced by 0.06 by extinction due to gas and dust along the line of sight. The star has a negligible radial velocity of 0.1 km/s, but with a relatively large proper motion, traversing the celestial sphere at an angular rate of 0.208″·yr−1.
