EZ Aquarii

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Multiple star
EZ Aquarii
Model of a triple star system in which the binary system (1-2) rotates with the third body (3) around the common barycentre.
Model of a triple star system in which the binary system (1-2) rotates with the third body (3) around the common barycentre .
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Aquarius
Right ascension 22 h 38 m 33.57 s
declination -15 ° 17 ′ 59.8 ″
Apparent brightness 12.87 mag
Typing
B − V color index 1.95 
U − B color index 1.43 
R − I index 3.44 
Spectral class M5V B
Variable star type UV + BY 
Astrometry
Radial velocity (−60.0) km / s
parallax (293.6 ± 0.9)  mas
distance (11.1 ± 0.1)  ly
(3.40 ± 0.04)  pc  
Proper movement 
Rec. Share: (2314 ± 8)  mas / a
Dec. portion: (2295 ± 8)  mas / a
Physical Properties
Dimensions 0.12 / 0.11 / 0.09  M ☉
Other names
and catalog entries
Gliese catalog FY 866 [1]
2MASS catalog 2MASS J22383372-1517573 [2]
Other names V * EZ Aqr, L 789-6, LP 820-64, UBV 19358, ** BLA 10, LPM 837, UCAC2 26361351, CSI-15-22358, LTT 9122, UCAC4 374-178693, 1E 2235.8-1534, WDS J22385 -1519AB, 2E 4631, GSC 06386-00505, NLTT 54407, WEB 19966, 2E 2235.8-1534, JP11 5181, 8pc 289.50, WISEA J223835.27-151735.3, GALEX 6376474988285791335, JP11 5180, PLX 5475, JP11. GCRkh 333, PLX 5475, ZCRkh 333, 5195, PLX 5475.00, [GKL99] 430, GCRV 26202, LFT 1729, PM 22358-1535, [RHG95] 3561, GEN # +6.10010866, LHS 68, PMSC 22329-1552, Gaia DR2 2596740426912781696, G 156-31, 1RXS J223832 .0-151809

EZ Aquarii also Luyten 789-6 or Gliese 866 is a star system that consists of three red dwarfs of the spectral class M and is therefore one of the BY-Draconis stars . It is approximately 11.1 light years (3.4 pc ) from our solar system and is located in the constellation Aquarius .

System structure

The pair EZ Aquarii AC forms a spectroscopic binary system with a period of 3.8 days and a distance of 0.03 AU . EZ Aquarii AC shares a common orbit with EZ Aquarii B, with a duration of 823 days. The A and B components both emit X-rays.

observation

The star with the number 866 in the Gliese catalog was considered a single star for thirty years. In 1986, astronomers at the Max Planck Institute for Astronomy (MPIA) discovered a companion with the help of high-resolution speckle interferometry at a distance of only 0.4 arc seconds from the main star. French astronomers discovered a third, previously unknown companion star during further spectroscopic examinations of GJ 866 in 1999.

The high self-movement of EZ Aquarii was discovered by Willem Jacob Luyten . All three stars could belong to the class of flare stars , since their masses are in the vicinity of the lower limit value for hydrogen fusion of at least 0.08 M ⊙ or 83 Jupiter masses , and their core heat can only be transported by convection .

By combining data sets, the individual stellar masses could be determined with an accuracy of ≈ 1%.

component Mass in M ⊙
A. 0.1187 ± 0.0011
B. 0.1145 ± 0.0012
C. 0.0930 ± 0.0008

EZ Aquarii C is the weakest member of the system, and the only star with a dynamically determined mass that is safely below 0.1 M ⊙ .

The configuration of the inner binary pair could allow an orbiting planet to orbit near its habitable zone . EZ Aquarii is approaching our solar system and will be at a minimum distance of about 8.2 light years (2.5 pc ) from the Sun in approximately 32,300 years . The nearest neighbor, Lacaille 9352, is about 4.1 light years from EZ Aquarii.

Individual evidence

  1. ↑ a b c d e f g h i SIMBAD : EZ Aqr. Retrieved September 23, 2019 .
  2. ↑ a b VSX: EZ Aqr. Retrieved September 23, 2019 .
  3. ↑ a b c X. Delfosse, et al .: Accurate masses of very low mass stars: II The very low mass triple system Gl 866 . In: Astronomy & Astrophysics, 350: L39-L42 . September 23, 1999. arxiv : astro-ph / 9909409 .
  4. ↑ Schmitt, JHMM, et al .: An Einstein Observatory X-ray survey of main-sequence stars with shallow convection zones . In: Astrophysical Journal, Vol. 290, p. 307-320 (1985) . March 1, 1985. bibcode : 1985ApJ ... 290..307S . doi : 10.1086 / 162986 .
  5. ^ Max Planck Institute for Astronomy, Annual Report 1999. In: Max Planck Institute for Astronomy, Heidelberg. 2001, accessed February 12, 2020 .
  6. ^ EA Popova, et al .: On possible circumbinary configurations of the planetary systems of α Centauri and EZ Aquarii . In: Astronomy Letters, April 2016, Volume 42, Issue 4, pp 260–267 . May 12, 2016. bibcode : 2016AstL ... 42..260P . doi : 10.1134 / S106377371604006X .
  7. ↑ VV Bobylev: Stars outside the Hipparcos list closely encountering the solar system . In: Astronomy Letters, November 2010, Volume 36, Issue 11, pp 816–822 . October 19, 2010. arxiv : 1009.4856 . bibcode : 2010AstL ... 36..816B . doi : 10.1134 / S1063773710110071 .
  8. ^ EZ Aquarii 3. In: Sol Company, solstation.com. 2011, accessed February 11, 2020 .