- An ultraviolet band light curve for a flare on EQ Pegasi B, adapted from Mathioudakis et al. (2006) [18]
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 | |
Exoplanet Archive | data |
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]
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]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 2.26±0.57 MJ | 0.64282±0.00068 | 284.39±1.47 | 0.35±0.19 | 69.20±25.61 ° | — |
In 1998, it was the basis of a hoax, as a telecommunications company claimed it had discovered "alien" signals originating from the star. [16]