* Astronomy

Title: The orbits of the quadruple star system 88 Tau A from PHASES differential astrometry and radial velocity
Authors: Benjamin F. Lane (Draper), Matthew W. Muterspaugh (Berkeley), Francis C. Fekel (Tennessee State), Michael Williamson (Tennessee State), Stanley Browne (Berkeley), Maciej Konacki (NCAC Polish Academy of Sciences), Bernard F. Burke (MIT), S. R. Kulkarni (Caltech), M. M. Colavita (JPL), M. Shao (JPL)
(Version v2)

We have used high precision differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) project and radial velocity measurements covering a time-span of 20 years to determine the orbital parameters of the 88 Tau A system. 88 Tau is a complex hierarchical multiple system comprising a total of six stars; we have studied the brightest 4, consisting of two short-period pairs orbiting each other with an 18-year period. We present the first orbital solution for one of the short-period pairs, and determine the masses of the components and distance to the system to the level of a few percent. In addition, our astrometric measurements allow us to make the first determination of the mutual inclinations of the orbits. We find that the sub-systems are not coplanar.

Read more  (72kb, PDF)