HD 220105

HD 220105 is a star in the northern constellation of Andromeda, and a member of the Sirius supercluster.^[9] It lies near the lower limit of visibility to the naked eye at an apparent visual magnitude of 6.24, and can be a challenge to spot under normal viewing conditions. The star is located 238 light years away, based upon an annual parallax shift of 13.78 mas. It is moving closer to the Earth with a heliocentric radial velocity of −2 km/s.

HD 220105

Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda[1]
Right ascension	23h 20m 44.09845s[2]
Declination	+44° 06′ 58.1997″[2]
Apparent magnitude (V)	6.24[3]
Characteristics
Evolutionary stage	main sequence[4][2]
Spectral type	A5 Vn[5]
U−B color index	0.10[3]
B−V color index	0.14[3]
Astrometry
Radial velocity (Rv)	−1.8[6] km/s
Proper motion (μ)	RA: −9.582[2] mas/yr Dec.: −37.026[2] mas/yr
Parallax (π)	13.7783±0.0277 mas[2]
Distance	236.7 ± 0.5 ly (72.6 ± 0.1 pc)
Absolute magnitude (MV)	+1.87[1]
Details
Mass	1.85[7] M☉
Radius	1.8[2] R☉
Luminosity	18.6[2] L☉
Surface gravity (log g)	4.19±0.14[7] cgs
Temperature	8,367±284[7] K
Rotational velocity (v sin i)	259[4] km/s
Age	525[7] Myr
Other designations
BD+43°4440, HD 220105, HIP 115261, HR 8884, SAO 52927, WDS J23207+4407A[8]
Database references
SIMBAD	data

This is an A-type main-sequence star with a stellar classification of A5 Vn, where the 'n' notation indicates "nebulous" absorption lines due to rapid rotation. It is around 525 million years old with a high projected rotational velocity of 259 km/s. The star has 1.85 times the mass of the Sun and is radiating 19 times the Sun's luminosity from its photosphere at an effective temperature of 8,367 K.

HD 220105 has a magnitude 10.13 companion located at an angular separation of 13.60″ along a position angle of 178°, as of 2015,^[10] and it is listed as a close binary by Zorec and Royer (2012).^[4] These coordinates are a source for X-ray emission with a luminosity of 1.212×10²² W, which is most likely coming from the faint companion.^[11]