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ADS 9731

ADS 9731
Observation data
Epoch J2000      Equinox J2000
Constellation Corona Borealis
Right ascension 15h 38m 12.91478s[1]
Declination +36° 14′ 48.5597″[1]
Apparent magnitude (V) 6.9 (total)[citation needed]
Characteristics
Spectral type F4V, F5V, G4V, F3V, F7V, M3V?[2]
Astrometry
A
Proper motion (μ) RA: 73.197[3] mas/yr
Dec.: −57.740[3] mas/yr
Parallax (π)9.0945 ± 0.0175 mas[3]
Distance358.6 ± 0.7 ly
(110.0 ± 0.2 pc)
B
Proper motion (μ) RA: 71.824[4] mas/yr
Dec.: −54.140[4] mas/yr
Parallax (π)9.1101 ± 0.0307 mas[4]
Distance358 ± 1 ly
(109.8 ± 0.4 pc)
C
Proper motion (μ) RA: 75.165[5] mas/yr
Dec.: −59.731[5] mas/yr
Parallax (π)9.0970 ± 0.0199 mas[5]
Distance358.5 ± 0.8 ly
(109.9 ± 0.2 pc)
D
Proper motion (μ) RA: 72.818[6] mas/yr
Dec.: −58.281[6] mas/yr
Parallax (π)9.0870 ± 0.0322 mas[6]
Distance359 ± 1 ly
(110.0 ± 0.4 pc)
Orbit
Other designations
BD+36°2626, HD 139691, CCDM J15382+3615AB, WDS J15382+3615AB
Database references
SIMBADdata

ADS 9731 is a star system that consists of six stars, located in the constellation of Corona Borealis. Four of the stars are visually separate in the sky, forming a visual star system, which was resolved using adaptive optics in 1995.[7] Two of these stars were themselves found to be spectroscopic binaries in 1998, resulting in a total of six known stars in the system.[2] It is one of very few multiple star systems known to have at least six members.[2]

Aa
Period = 3.27 d
Ab
Period = 450 y
B
Period = 20,000 y
C
Period = 1000 y
Da
Period = 14.28 d
Db

Hierarchy of orbits

The components are organised thus: Aa and Ab are yellow-white main sequence stars of spectral types F4V and F5V and 1.35 and 1.32 solar masses respectively, which orbit each other every 3.27 days. This pair is in a 450-year orbit with star B, a star of spectral type G4V that has around the same mass as the Sun. Star C is a yellow white star of spectral type F3V around 1.41 times as massive as the sun, which has just started brightening and moving off the main sequence. It is in a 1000-year orbit with a pair of stars, Da and Db, a yellow-white main sequence star of spectral type F7V and a red dwarf of spectral type M3V. Da and Db take 14.28-days to orbit each other. Finally the system of stars C and Dab, and the system of stars Aab and B, take over 20,000 years to orbit each other.[2]

The combined light from the whole system results in an integrated V magnitude of 6.9. Published apparent magnitudes for the components vary greatly and some are certainly in error,[2] but components A, B, C, and D are approximately of visual magnitude 8, 10, 9, and 9 respectively.[8] Models of all six components show that Aa and Ab have magnitudes 8.5 and 8.7 respectively while the faint secondary to component D is about 16th magnitude. The CD pair is slightly brighter than the AB pair, although component A is slightly brighter than component C.[2]

Gaia EDR3 catalogues parallaxes for the four resolved stars, all at a distance of 360 light-years (110 pc) with a statistical margin of error of less than a parsec.

The star system has been considered as a possible target for direct imaging searches for exoplanets,[9] but no planets have yet been detected in the system.

  1. ^ a b Cite error: The named reference hipparcos2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Tokovinin was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference edr3a was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference edr3b was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference edr3c was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference edr3d was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Drummond was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference wds was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Janson was invoked but never defined (see the help page).

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