Gliese 22

Gliese 22

File:Gliese22ALightCurve.png A blue band light curve for a flare of Gliese 22A, adapted from Pettersen (1975)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cassiopeia
Gliese 22 A
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	10.29
Gliese 22 B
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	12.19
Gliese 22 C
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	13.2
Characteristics
Spectral type	M2.5Ve / M3V
U−B Template:Engvar	1.16
B−V Template:Engvar	1.54
R−I Template:Engvar	0.99
Variable type	Flare stars
Astrometry
Radial velocity (Rv)	10 km/s
Proper motion (μ)	RA: 1739.0 mas/yr Dec.: −224.93 mas/yr
Parallax (π)	99.35±2.17 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	10.26
Orbit
Primary	Gliese 22 AC
Companion	Gliese 22 B
Period (P)	223.3 yr
Semi-major axis (a)	3.322″
Eccentricity (e)	0.293
Inclination (i)	47.3°
Longitude of the node (Ω)	174.9°
Periastron epoch (T)	JD 1859.4
Argument of periastron (ω) (secondary)	146.3°
Orbit
Primary	Gliese 22 A (Aa)
Companion	Gliese 22 C (Ab)
Period (P)	days
Semi-major axis (a)	″
Eccentricity (e)
Inclination (i)	°
Longitude of the node (Ω)	°
Periastron epoch (T)	JD 51817.2
Argument of periastron (ω) (secondary)	°
Details
Mass	0.378(A) + 0.136(C) Template:Solar mass
Radius	0.5(A) Template:Solar radius
Luminosity	0.04 Template:Solar luminosity
Temperature	2000–3500 K
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Details
B
Mass	0.382 Template:Solar mass
Radius	0.394 Template:Solar radius
Luminosity	0.011 Template:Solar luminosity
Temperature	3,339 K
Metallicity [Fe/H]	−0.24 dex
Rotational velocity (v sin i)	<4 km/s
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
2MASS J00322970+6714080, BD+66°34, CCDM J00325+6714, GJ 22, HIP 2552, LFT 47, V547 Cassiopeiae, ADS 440
Database references
SIMBAD	A
	B
Exoplanet Archive	data

Gliese 22, also catalogued V547 Cassiopeiae or ADS 440, is a hierarchical star system approximately 33 light-years away in the constellation of Cassiopeia. The system consists of pair of red dwarf stars, Gliese 22A and Gliese 22C, orbited by a third red dwarf Gliese 22B in an outer orbit of about 223 years.

The discovery of flare activity on Gliese 22A was announced by Bjørn Ragnvald Pettersen in 1975, which led to it being given a variable star designation, V547 Cassiopeiae, in 1977.

Planetary system

As of 2008, it was announced that a possible extrasolar planet, Gliese 22B b, orbits Gliese 22B but this is currently unconfirmed. The study in 2011 has indicated the orbit of the purported planet is stable.

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