EQ Pegasi (also known as Gliese 896) is a nearby binary system of two red dwarfs. Both components are flare stars, with spectral types of M4Ve and M6Ve respectively, and a current separation between the components of 5.8 arcseconds. The system is at a distance of 20.4 light-years, and is 950 million years old.^[11] The primary star is orbited by one known exoplanet.^[4]

Quick Facts Observation data Epoch J2000.0 Equinox J2000.0, Apparent magnitude (V) ...

EQ Pegasi

EQ Location of EQ Pegasi in the constellation Pegasus
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Pegasus
EQ Pegasi A
Right ascension	23h 31m 52.17385s[1]
Declination	+19° 56′ 14.1304″[1]
Apparent magnitude (V)	10.38 (min)[2]
EQ Pegasi B
Right ascension	23h 31m 52.57534s[3]
Declination	+19° 56′ 14.0050″[3]
Apparent magnitude (V)	12.58 (min)[2]
Characteristics
EQ Pegasi A
Evolutionary stage	red dwarf
Spectral type	M4Ve[2]
Variable type	Flare star[2]
EQ Pegasi B
Evolutionary stage	red dwarf
Spectral type	M6Ve[2]
Variable type	Flare star[2]
Astrometry
EQ Pegasi A
Radial velocity (Rv)	−0.21±0.82[1] km/s
Proper motion (μ)	RA: 578.009(35) mas/yr[1] Dec.: −59.769(23) mas/yr[1]
Parallax (π)	159.6634 ± 0.0341 mas[1]
Distance	20.428 ± 0.004 ly (6.263 ± 0.001 pc)
EQ Pegasi B
Proper motion (μ)	RA: 552.349(55) mas/yr[3] Dec.: 20.275(36) mas/yr[3]
Parallax (π)	159.9085 ± 0.0513 mas[3]
Distance	20.396 ± 0.007 ly (6.254 ± 0.002 pc)
Orbit[4]
Period (P)	83,664.63 ± 1.98 days (229.0613 ± 0.0054 a)
Semi-major axis (a)	5.05797±0.00043" (31.635±0.033 AU)
Eccentricity (e)	0.108047±0.000053
Inclination (i)	130.065±0.010°
Longitude of the node (Ω)	255.0919±0.0034°
Periastron epoch (T)	2,401,891.34±1.19
Argument of periastron (ω) (secondary)	307.1416±0.0045°
Details
A
Mass	0.43599±0.00092[4] M☉
Radius	0.35[5] R☉
Luminosity	0.019[6] L☉
Temperature	3,585[7] K
Rotation	1.061 days[5]
B
Mass	0.16527±0.00025[4] M☉
Radius	0.25[5] R☉
Luminosity	0.008[6] L☉
Temperature	3,309[8] K
Rotation	0.404 days[5]
Other designations
EQ Peg, BD+19°5116, GJ 896, HIP 116132, WDS J23317+1956AB, G 68-24, G 129-19, G 128-71, LFT 1799, LHS 3965, LTT 16919, NLTT 57135[9]
EQ Peg A: TYC 1723-23-1, 2MASS J23315208+1956142[10]
EQ Peg B: LFT 1800, LHS 3966, LTT 16920, NLTT 57136, TYC 1723-23-2, 2MASS J23315244+1956138[10]
Database references
SIMBAD	The system
	A
	B

Close

EQ Pegasi was first noticed to be a binary star by Carl A. Wirtanen who in the course of a systematic survey of the McCormick Observatory photographic plates for M-type dwarfs, detected a companion about two magnitudes fainter at a separation of 3.5 arcseconds.^[12]

Both components were also thought to be single-lined spectroscopic binaries, with faint companions that have not been resolved in orbits of a few years,^[13][14] but this is no longer thought to be the case. A 2021 study of nearby stars states that "the spectroscopic binarity classification [...] is almost certainly due to activity".^[15]

In 2022, a Jovian planet was discovered in orbit around the system's primary star via radio astrometry. Along with the planet around TVLM 513-46546, this is the first confirmed exoplanet discovered entirely using astrometry.^[4]

In 1998, it was the basis of a hoax, as a telecommunications company claimed it had discovered "alien" signals originating from the star.^[16]