8 Andromedae
Multiple star system in the constellation Andromeda
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8 Andromedae, abbreviated 8 And, is a probable triple star[12] system in the northern constellation of Andromeda. 8 Andromedae is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 4.82.[2] Based upon an annual parallax shift of 5.7 mas, it is located about 570 light years from the Earth. It is moving closer with a heliocentric radial velocity of −8 km/s.[6]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 17m 44.64727s[1] |
| Declination | +49° 00′ 55.0829″[1] |
| Apparent magnitude (V) | 4.82[2] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | M2.5 III Ba0.5[4] |
| B−V color index | 1.673[5] |
| Astrometry | |
| Radial velocity (Rv) | −8.0±0.3[6] km/s |
| Proper motion (μ) | RA: +33.779[1] mas/yr Dec.: +6.213[1] mas/yr |
| Parallax (π) | 5.6963±0.1030 mas[1] |
| Distance | 570 ± 10 ly (176 ± 3 pc) |
| Absolute magnitude (MV) | −1.727[5] |
| Details | |
| Radius | 30[7] R☉ |
| Surface gravity (log g) | 1.00±0.25[8] cgs |
| Temperature | 3,616±22[8] K |
| Metallicity [Fe/H] | +0.04±0.08[8] dex |
| Rotational velocity (v sin i) | 5.0±1.0[9] km/s |
| Other designations | |
| 8 And, NSV 14484, BD+48°3991, HD 219734, HIP 115022, HR 8860, SAO 52871, PPM 64030, WDS J23177+4901A[10] | |
| Database references | |
| SIMBAD | data |
The primary component is an ageing red giant star with a stellar classification of M2.5 III Ba0.5.[4] The suffix notation indicates this is a mild barium star, which means the stellar atmosphere is enriched with s-process elements. It is either a member of a close binary system and has previously acquired these elements from a (now) white dwarf companion or else it is on the asymptotic giant branch and is generating the elements itself.[13] This is a periodic variable of unknown type, changing in brightness with an amplitude of 0.0161 magnitude at a frequency of 0.23354 d−1, or once every 4.3 days.[14]
The third component is the magnitude 13.0 star at an angular separation of 7.8″ along a position angle of 164°, as of 2015.[15] It has a Gaia Data Release 3 parallax of 5.7 mas and a proper motion almost identical to 8 Andromedae.[16] A number of other faint stars within a few arc-minutes of 8 Andromedae have been listed as companions, but none are at the same distance.[17]
Within Andromeda it is the second of a northerly chain asterism – 11 is further south-westward, with 7, 5, then 3 Andromedae in the other direction.