EZ Aquarii

EZ Aquarii is a triple star system approximately 11.3 ly (3.5 pc) from the Sun in the constellation Aquarius. It is also known as Luyten 789-6 and Gliese 866 and all three components are M-type red dwarfs. The pair EZ Aquarii AC form a spectroscopic binary with a 3.8-day orbit and a 0.03 AU separation. This pair share an orbit with EZ Aquarii B that has an 823-day period.[8] The A and B components of Luyten 789-6 together emit X-rays.[9]

EZ Aquarii A/B/C
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension  22h 38m 33.73s[1]
Declination –15° 17′ 57.3″[1]
Apparent magnitude (V) 12.87 (13.33/13.27/14.03)[2]
Characteristics
Spectral type M5 V[2]
U−B color index +1.54
B−V color index +1.96[3]
R−I color index +0.64
Astrometry
Radial velocity (Rv)–59.9[4] km/s
Proper motion (μ) RA: +2314[5] mas/yr
Dec.: +2295[5] mas/yr
Parallax (π)294.3 ± 3.5[6] mas
Distance11.1 ± 0.1 ly
(3.40 ± 0.04 pc)
Absolute magnitude (MV)15.64/15.58/16.34[2]
Details
Mass0.11/0.11/0.10[2] M☉
Orbit[7]
PrimaryEZ Aquarii AC
CompanionEZ Aquarii B
Period (P)2.2506 ± 0.0033 yr
Semi-major axis (a)0.346″ ± 0.004″
Eccentricity (e)0.437 ± 0.007
Inclination (i)112.4° ± 0.5°
Longitude of the node (Ω)162.1° ± 0.4°
Periastron epoch (T)1987.236 ± 0.014
Argument of periastron (ω)
(secondary)		–17.7° ± 1.1°
Other designations
Luyten 789-6, GCTP 5475.00, LHS 68, GJ 866, G 156-031.
Database references
SIMBADdata

The configuration of the inner binary pair may permit a circumbinary planet to orbit near their habitable zone.[10] EZ Aquarii is approaching the Solar System and, in about 32,300 years, will be at its minimal distance of about 8.2 ly (2.5 pc) from the Sun.[11] The ChView simulation shows that currently its nearest neighbouring star is Lacaille 9352 at about 4.1 ly (1.3 pc) from EZ Aquarii.

See also
  • List of nearest stars

References
  1. Cutri, R. M.; et al. (June 2003). 2MASS All Sky Catalog of point sources. NASA. Bibcode:2003tmc..book.....C.
  2. "The One Hundred Nearest Star Systems". RECONS. Georgia State University. Archived from the original on 2012-05-13. Retrieved 2010-06-30.
  3. Eggen, O. J.; Greenstein, J. L. (October 1965). "Observations of proper-motion stars. II". Astrophysical Journal. 142: 925. Bibcode:1965ApJ...142..925E. doi:10.1086/148362.
  4. Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W.
  5. Salim, Samir; Gould, Andrew (January 2003). "Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog". The Astrophysical Journal. 582 (2): 1011–1031. arXiv:astro-ph/0206318. Bibcode:2003ApJ...582.1011S. doi:10.1086/344822.
  6. Gliese, W.; Jahreiß, H. (1991). "Gl 866". Preliminary Version of the Third Catalogue of Nearby Stars. Retrieved 2014-10-20.
  7. Woitas, J.; Leinert, Ch.; Jahreiß, H.; Henry, T.; Franz, O. G.; Wasserman, L. H.; Leinert; Jahreiß; Henry; Franz; Wasserman (January 2000). "The nearby M-dwarf system Gliese 866 revisited". Astronomy and Astrophysics. 353: 253–256. arXiv:astro-ph/9910411. Bibcode:2000A&A...353..253W.CS1 maint: multiple names: authors list (link)
  8. Delfosse, X.; et al. (October 1999), "Accurate masses of very low mass stars. II. The very low mass triple system GL 866", Astronomy and Astrophysics, 350: L39–L42, arXiv:astro-ph/9909409, Bibcode:1999A&A...350L..39D
  9. Schmitt, J.H.M.M.; Golub, L.; Harnden, F.R. Jr.; Maxson, C.W.; Rosner, R.; Vaiana, G.S. (March 1985). "An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones". Astrophysical Journal. 290 (Part 1): 307–320. Bibcode:1985ApJ...290..307S. doi:10.1086/162986.
  10. Popova, E. A.; Shevchenko, I. I. (April 2016), "On possible circumbinary configurations of the planetary systems of α Centauri and EZ Aquarii", Astronomy Letters, 42 (4): 260–267, Bibcode:2016AstL...42..260P, doi:10.1134/S106377371604006X.
  11. Bobylev, V. V. (November 2010), "Stars outside the Hipparcos list closely encountering the Solar system", Astronomy Letters, 36 (11): 816–822, arXiv:1009.4856, Bibcode:2010AstL...36..816B, doi:10.1134/S1063773710110071
EZ Aquarii Star System. Credit: SpaceEngine/Bob Trembley
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