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Star system with 6 stars in the constellation Corona Borealis From Wikipedia, the free encyclopedia
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
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] |
Distance | 358.6 ± 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] |
Distance | 358 ± 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] |
Distance | 358.5 ± 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] |
Distance | 359 ± 1 ly (110.0 ± 0.4 pc) |
Orbit | |
Other designations | |
Database references | |
SIMBAD | data |
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.