EQ Pegasi
EQ Pegasi is located in the constellation Pegasus
EQ Pegasi is located in the constellation Pegasus
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]
Distance20.428 ± 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]
Distance20.396 ± 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
Mass0.43599±0.00092[4] M☉
Radius0.35[5] R☉
Luminosity0.019[6] L☉
Temperature3,585[7] K
Rotation1.061 days[5]
B
Mass0.16527±0.00025[4] M☉
Radius0.25[5] R☉
Luminosity0.008[6] L☉
Temperature3,309[8] K
Rotation0.404 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
SIMBADThe system
A
B

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]

Discovery

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]

Planetary system

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]

The Gliese 896 A planetary system[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 culture

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

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 4 5 6 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. 1 2 3 4 5 6 Curiel, Salvador; Ortiz-León, Gisela N.; Mioduszewski, Amy J.; Sanchez-Bermudez, Joel (September 2022). "3D Orbital Architecture of a Dwarf Binary System and Its Planetary Companion". The Astronomical Journal. 164 (3): 93. arXiv:2208.14553. Bibcode:2022AJ....164...93C. doi:10.3847/1538-3881/ac7c66. S2CID 251953478.
  5. 1 2 3 4 Morin, J.; Donati, J.-F.; et al. (October 2008). "Large-scale magnetic topologies of mid M dwarfs". Monthly Notices of the Royal Astronomical Society. 390 (2): 567–581. arXiv:0808.1423. Bibcode:2008MNRAS.390..567M. doi:10.1111/j.1365-2966.2008.13809.x. S2CID 11240756.
  6. 1 2 Morales, J. C.; Ribas, I.; Jordi, C. (2008). "The effect of activity on stellar temperatures and radii". Astronomy and Astrophysics. 478 (2): 507. arXiv:0711.3523. Bibcode:2008A&A...478..507M. doi:10.1051/0004-6361:20078324. S2CID 16238033.
  7. ↑ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  8. ↑ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  9. ↑ "BD+19 5116". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 August 2017.
  10. 1 2 "BD+19 5116A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 August 2017.
  11. ↑ Crosley, M. K.; Osten, R. A. (2018). "Constraining Stellar Coronal Mass Ejections through Multi-wavelength Analysis of the Active M Dwarf EQ Peg". The Astrophysical Journal. 856 (1). 39. arXiv:1802.03440. Bibcode:2018ApJ...856...39C. doi:10.3847/1538-4357/aaaec2. S2CID 55448675.
  12. ↑ Wirtanen, C. A. (1941). "A New dMe Double Star". Publications of the Astronomical Society of the Pacific. 53 (316): 340. Bibcode:1941PASP...53..340W. doi:10.1086/125371.
  13. ↑ Tokovinin, A. "Multiple Star Catalog". Retrieved 2019-08-12.
  14. ↑ Delfosse, X.; Forveille, T.; et al. (April 1999). "New neighbours. I. 13 new companions to nearby M dwarfs". Astronomy and Astrophysics. 344: 897–910. arXiv:astro-ph/9812008. Bibcode:1999A&A...344..897D.
  15. ↑ Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (30 April 2021). "The 10 parsec sample in the Gaia era". Astronomy & Astrophysics. 650: A201. arXiv:2104.14972. Bibcode:2021A&A...650A.201R. doi:10.1051/0004-6361/202140985. S2CID 233476431. Data available at https://gruze.org/10pc/
  16. ↑ "BBC News | Sci/Tech | Alien hoax dismays scientists". news.bbc.co.uk. Retrieved 2018-09-25.
  17. ↑ Norton, A. J.; Wheatley, P. J.; West, R. G.; Haswell, C. A.; Street, R. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I.; Enoch, B.; Gallaway, M.; Hellier, C.; Horne, K.; Irwin, J.; Kane, S. R.; Lister, T. A.; Nicholas, J. P.; Parley, N.; Pollacco, D.; Ryans, R.; Skillen, I.; WilsonD. M. (May 2007). "New periodic variable stars coincident with ROSAT sources discovered using SuperWASP". Astronomy and Astrophysics. 467 (2): 785–905. arXiv:astro-ph/0702631. Bibcode:2007A&A...467..785N. doi:10.1051/0004-6361:20077084. S2CID 16358048. Retrieved 11 February 2022.
  18. ↑ Mathioudakis, M.; Bloomfield, D. S.; Jess, D. B.; Dhillon, V. S.; Marsh, T. R. (September 2006). "The periodic variations of a white-light flare observed with ULTRACAM". Astronomy and Astrophysics. 456 (1): 323–327. arXiv:astro-ph/0605196. Bibcode:2006A&A...456..323M. doi:10.1051/0004-6361:20054752. S2CID 8572363. Retrieved 12 February 2022.
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