8 Andromedae

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8 Andromedae
Template:Location mark
Location of 8 Andromedae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.82[2]
Characteristics
Evolutionary stage AGB[3]
Spectral type M2.5 III Ba0.5[4]
B−V Template:Engvar 1.673[5]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[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]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−1.727[5]
Details
Radius30[7] Template:Solar radius
Surface gravity (log g)Script error: No such module "val".[8] cgs
TemperatureScript error: No such module "val".[8] K
Metallicity [Fe/H]Script error: No such module "val".[8] dex
Rotational velocity (v sin i)Script error: No such module "val".[9] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[10]
Database references
SIMBADdata

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File:8AndLightCurve.png
A light curve for 8 Andromedae, plotted from Hipparcos data[11]

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 Script error: No such module "val"., it is located about 570 light years from the Earth. It is moving closer with a heliocentric radial velocity of −8 km/s.[6]

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 Script error: No such module "val". along a position angle of 164°, as of 2015.[15] It has a Gaia Data Release 3 parallax of Script error: No such module "val". 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.

References

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Template:Stars of Andromeda