Girish Mahajan (Editor)

ADS 9731

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

The combined light from the whole system results in an integrated V magnitude of 6.9. The parallax measured by the Hipparcos satellite indicates that the system is relatively nearby at around 110 parsecs (360 light-years) from the Sun. However, this distance is highly uncertain because the multiple stars in the system prevented Hipparcos from accurately measuring the parallax; the system may instead be at a distance of about 200 pc (650 ly).

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

References

ADS 9731 Wikipedia