OP Andromedae

OP Andromedae

File:OPAndLightCurve.png The visual band light curve of OP Andromedae, adapted from Barksdale et al. (1984)
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	Template:RA
Declination	Template:DEC}
Apparent magnitude (V)	6.27 - 6.41
Characteristics
Spectral type	K1III
Apparent magnitude (J)	3.794
Apparent magnitude (H)	3.165
Apparent magnitude (K)	2.914
B−V Template:Engvar	1.2478
Variable type	RS CVn
Astrometry
Radial velocity (Rv)	km/s
Proper motion (μ)	RA:  mas/yr Dec.:  mas/yr
Parallax (π)	6.3462±0.0912 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	0.37 ± 0.23
Details
Mass	1.5 – 3 Template:Solar mass
Radius	Template:Solar radius
Luminosity	128.825 Template:Solar luminosity
Surface gravity (log g)	2.14 cgs
Temperature	4,490 K
Metallicity [Fe/H]	-0.10 dex
Rotational velocity (v sin i)	7.2 km/s
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
2MASS J01362720+4843221, BD+47° 460, HD 9746, HIP 7493, SAO 37351, PPM 44205, HR 454, TYC 3282-2270-1
Database references
SIMBAD	data

OP Andromedae is a variable star in the constellation Andromeda. Varying between magnitudes 6.27 and 6.41 over 2.36 days, it has been classified as an RS Canum Venaticorum variable, but there has not been any proof of binarity, yet. It is a red giant star with a spectral classification of K1III.

OP Andromedae is one of the few red giant stars where it was detected an overabundance of ⁷Li. The mechanism that enhances lithium in red giants is still unknown. It was proposed that those stars engulfed planets in the recent past; however, this theory was discarded since there is an overabundance of just one lithium isotope.