6 Andromedae is an astrometric binary star[7] system in the northern constellation of Andromeda. The designation comes from the star catalogue of John Flamsteed, first published in 1712. Its apparent visual magnitude is 5.91,[2] which is just bright enough to be visible to the naked eye under good seeing conditions. Based upon an annual parallax shift of 34.1 mas as seen from Earth,[1] it is around 96 light years from the Sun. It is moving closer to the Sun with a radial velocity of −32.4 km/s.[2] The system has a relatively high proper motion, advancing across the celestial sphere at the rate of 0.272 arc seconds per annum.[8]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Andromeda |
Right ascension | 23h 10m 27.23746s[1] |
Declination | +43° 32′ 38.4336″[1] |
Apparent magnitude (V) | 5.91[2] |
Characteristics | |
Spectral type | F5 V[3] |
U−B color index | −0.05[3] |
B−V color index | +0.450±0.004[2] |
Astrometry | |
Radial velocity (Rv) | −32.4±0.7[2] km/s |
Proper motion (μ) | RA: +209.057[1] mas/yr Dec.: +138.052[1] mas/yr |
Parallax (π) | 34.1008 ± 0.1650 mas[1] |
Distance | 95.6 ± 0.5 ly (29.3 ± 0.1 pc) |
Absolute magnitude (MV) | 3.71[2] |
Orbit[3] | |
Period (P) | 3,373±6 d |
Periastron epoch (T) | 53116 ± 16 MJD |
Argument of periastron (ω) (secondary) | 165.2±2.0° |
Semi-amplitude (K1) (primary) | 8.75±0.09 km/s |
Details | |
Mass | 1.30[4] M☉ |
Radius | 1.50+0.03 −0.06[1] R☉ |
Luminosity | 3.090+0.018 −0.017[1] L☉ |
Surface gravity (log g) | 4.09±0.14[4] cgs |
Temperature | 6,425±218[4] K |
Metallicity [Fe/H] | −0.19±0.03[2] dex |
Rotational velocity (v sin i) | 18[5] km/s |
Age | 2.91[4] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
This is a single-lined spectroscopic binary with an orbital period of 9.2 years and an eccentricity of 0.3.[3] Some early observations of the star gave it a subgiant luminosity class and it was published in the Bright Star Catalogue as spectral class F5 IV. More modern measurements identify the visible component as an F-type main-sequence star with a stellar classification of F5 V.[3][9] The star is an estimated 2.9[4] billion years old with 1.3[4] times the mass of the Sun and 1.5[1] times the Sun's radius. It is radiating 3.1[1] times the Sun's luminosity from its photosphere at an effective temperature of around 6,425 K.[4] 6 Andromedae displays an infrared excess at a wavelength of 22 μm, which may indicate a circumstellar disk of warm dusty debris.[5]
The mass of the secondary component is roughly at or above that of the Sun. If it were a single, ordinary star, it should be readily visible as it would be just one magnitude fainter than the primary. The lack of conspicuous ultraviolet emission appears to rule out a white dwarf companion, so it may instead itself be a binary system consisting of two smaller stars having an orbital period between a week and a year.[3]