8 Andromedae

8 Andromedae

Template:Location mark Location of 8 Andromedae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	4.82
Characteristics
Evolutionary stage	AGB
Spectral type	M2.5 III Ba0.5
B−V Template:Engvar	1.673
Astrometry
Radial velocity (Rv)	Template:Val km/s
Proper motion (μ)	RA: +33.779 mas/yr Dec.: +6.213 mas/yr
Parallax (π)	5.6963±0.1030 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−1.727
Details
Radius	30 Template:Solar radius
Surface gravity (log g)	Template:Val cgs
Temperature	Template:Val K
Metallicity [Fe/H]	Template:Val dex
Rotational velocity (v sin i)	Template:Val km/s
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	data

File:8AndLightCurve.png

A light curve for 8 Andromedae, plotted from Hipparcos data

8 Andromedae, abbreviated 8 And, is a probable triple star 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. Based upon an annual parallax shift of Template:Val, it is located about 570 light years from the Earth. It is moving closer with a heliocentric radial velocity of −8 km/s.

The primary component is an ageing red giant star with a stellar classification of M2.5 III Ba0.5. 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. 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.

The third component is the magnitude 13.0 star at an angular separation of Template:Val along a position angle of 164°, as of 2015. It has a Gaia Data Release 3 parallax of Template:Val and a proper motion almost identical to 8 Andromedae. 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.

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.