47 Andromedae
Binary star system in the constellation Andromeda
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47 Andromedae is a binary star[2] system in the northern constellation of Andromeda. The designation is from the star catalogue of John Flamsteed, first published in 1712. The system has a combined apparent visual magnitude of 5.60,[2] which is just bright enough to be faintly visible to the naked eye under good seeing conditions. The distance to this system, as determined from an annual parallax shift of 15.76 mas,[1] is about 207 light years. It is moving away from the Sun with a heliocentric radial velocity of +14.14 km/s.[5]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 01h 23m 40.6163s[1] |
| Declination | +37° 42′ 53.799″[1] |
| Apparent magnitude (V) | 5.60 (6.33 + 6.38)[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | A1m[3] (kA1hF1mF2)[4] |
| B−V color index | 0.276[2] |
| Astrometry | |
| Radial velocity (Rv) | +14.14±0.02[5] km/s |
| Proper motion (μ) | RA: +82.131±0.089[1] mas/yr Dec.: −18.986±0.077[1] mas/yr |
| Parallax (π) | 15.7619±0.1269 mas[1] |
| Distance | 207 ± 2 ly (63.4 ± 0.5 pc) |
| Absolute magnitude (MV) | 2.30±0.06/2.35±0.06[2] |
| Orbit[5] | |
| Period (P) | 35.36836±0.00005 d |
| Semi-major axis (a) | 5.05±0.02 mas |
| Eccentricity (e) | 0.6476±0.0005 |
| Inclination (i) | 140.64±0.45° |
| Periastron epoch (T) | 54293.208±0.004 HJD |
| Semi-amplitude (K1) (primary) | 39.27±0.05 km/s |
| Semi-amplitude (K2) (secondary) | 40.47±0.05 km/s |
| Details[5] | |
| 47 And A | |
| Mass | 1.636±0.050 M☉ |
| Radius | 1.84±0.05 R☉ |
| Luminosity | 9.0±0.5[2] L☉ |
| Surface gravity (log g) | 4.16±0.02 cgs |
| Temperature | 7,280±110 K |
| Rotational velocity (v sin i) | 15.9±1.3 km/s |
| Age | 1.0±0.1 Gyr |
| 47 And B | |
| Mass | 1.587±0.049 M☉ |
| Radius | 1.66±0.12 R☉ |
| Luminosity | 8.6±0.5[2] L☉ |
| Surface gravity (log g) | 4.22±0.03 cgs |
| Temperature | 7,280±120 K |
| Rotational velocity (v sin i) | 15.2±1.4 km/s |
| Age | 1.0±0.1 Gyr |
| Other designations | |
| 47 And, BD+36°237, FK5 2093, HD 8374, HIP 6514, HR 395, SAO 54655, PPM 66233[6] | |
| Database references | |
| SIMBAD | data |
The binary nature of this system was discovered by John Stanley Plaskett and Reynold Kenneth Young in 1919 using radial velocity measurements taken from Photographic plates obtained at Dominion Astrophysical Observatory in Saanich, British Columbia, Canada.[7] It is a double-lined spectroscopic binary with an orbital period of 35.4 days and an eccentricity of 0.65. The components appear to be nearly identical Am stars, with a magnitude difference of 0.05.[2] The combined stellar classification is A1m.[3]