Astronomy:EQ Pegasi

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Short description: Star system in the constellation Pegasus

Coordinates: Sky map 23h 31m 52.1743s, +19° 56′ 14.1284″

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
{{#ifeq:J2000.0|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000.0      [[Astronomy:Equinox (celestial coordinates)|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)[1] mas/yr
Dec.: −59.769(23)[1] mas/yr
Parallax (π)159.6634 ± 0.0341[1] mas
Distance20.428 ± 0.004 ly
(6.263 ± 0.001 pc)
EQ Pegasi B
Proper motion (μ) RA: 552.349(55) mas/yr
Dec.: 20.275(36) mas/yr
Parallax (π)159.9085 ± 0.0513[3] mas
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 astronomical unit|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☉
Radius0.409±0.016[5] R☉
Luminosity0.019[6] L☉
Temperature3,353±60[5] K
Rotation1.061 days[7]
B
Mass0.16527±0.00025[4] M☉
Radius0.303±0.013[5] R☉
Luminosity0.008[6] L☉
Temperature3,072±60[5] K
Rotation0.404 days[7]
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[8]
EQ Peg A: TYC 1723-23-1, 2MASS J23315208+1956142[9]
EQ Peg B: LFT 1800, LHS 3966, LTT 16920, NLTT 57136, TYC 1723-23-2, 2MASS J23315244+1956138[9]
Database references
SIMBADThe system
A
B
Exoplanet Archivedata

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.[10] 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.[11]

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,[12][13] 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".[14]

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.[15]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Samus, N. N. 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. ↑ 3.0 3.1 3.2 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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. doi:10.3847/1538-3881/ac7c66. Bibcode: 2022AJ....164...93C. 
  5. ↑ 5.0 5.1 5.2 5.3 Mann, Andrew W. et al. (May 2015). "How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius". The Astrophysical Journal 804 (1): 38. doi:10.1088/0004-637X/804/1/64. 64. Bibcode: 2015ApJ...804...64M. 
  6. ↑ 6.0 6.1 Morales, J. C.; Ribas, I.; Jordi, C. (2008). "The effect of activity on stellar temperatures and radii". Astronomy and Astrophysics 478 (2): 507. doi:10.1051/0004-6361:20078324. Bibcode: 2008A&A...478..507M. 
  7. ↑ 7.0 7.1 Morin, J. et al. (October 2008). "Large-scale magnetic topologies of mid M dwarfs". Monthly Notices of the Royal Astronomical Society 390 (2): 567–581. doi:10.1111/j.1365-2966.2008.13809.x. Bibcode: 2008MNRAS.390..567M. 
  8. ↑ "BD+19 5116". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B19+5116. 
  9. ↑ 9.0 9.1 "BD+19 5116A". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B19+5116A. 
  10. ↑ 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. doi:10.3847/1538-4357/aaaec2. Bibcode: 2018ApJ...856...39C. 
  11. ↑ Wirtanen, C. A. (1941). "A New dMe Double Star". Publications of the Astronomical Society of the Pacific 53 (316): 340. doi:10.1086/125371. Bibcode: 1941PASP...53..340W. 
  12. ↑ Tokovinin, A.. "Multiple Star Catalog". http://www.ctio.noirlab.edu/~atokovin/stars/stars.php?cat=HIP&number=116132. 
  13. ↑ Delfosse, X. et al. (April 1999). "New neighbours. I. 13 new companions to nearby M dwarfs". Astronomy and Astrophysics 344: 897–910. Bibcode: 1999A&A...344..897D. 
  14. ↑ 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. doi:10.1051/0004-6361/202140985. Bibcode: 2021A&A...650A.201R.  Data available at https://gruze.org/10pc/
  15. ↑ "BBC News | Sci/Tech | Alien hoax dismays scientists". https://news.bbc.co.uk/2/hi/science/nature/206845.stm. 
  16. ↑ Norton, A. J.; Wheatley, P. J.; West, R. G.; Haswell, C. A.; Street, R. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I. et al. (May 2007). "New periodic variable stars coincident with ROSAT sources discovered using SuperWASP". Astronomy and Astrophysics 467 (2): 785–905. doi:10.1051/0004-6361:20077084. Bibcode: 2007A&A...467..785N. https://ui.adsabs.harvard.edu/abs/2007A&A...467..785N. Retrieved 11 February 2022. 
  17. ↑ 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. doi:10.1051/0004-6361:20054752. Bibcode: 2006A&A...456..323M. https://ui.adsabs.harvard.edu/abs/2006A&A...456..323M. Retrieved 12 February 2022. 



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