Dynamical Study of Exoplanet Host Stellar Systems: Upsilon Andromedae

The star upsilon Andromedae (50 And = HD 9826) is a high proper motion star of V = 4.10 and F8V spectral type, located at a distance of only 13.5 pc. Three exoplanets, ? And b, ? And c, ? And d, were detected between 1996 and 1999, and in 2011 a fourth planet was added to the system. This was the first multiple planetary system discovered. The star ? And has two optical wide companions, compo-nents B and C, at about 110 and 271 arcseconds. In 2002, Lowrance et al. detected a wide stellar com-panion, the D component, a M4.5V red dwarf star of V magnitude 14.1 with physical separation of about 55.6 arcsecond. In this work, digitized photographic plates and CCD images from online archives in ad-dition to astrometric catalogs (2MASS, WISE) were used to increase the number of astrometric measures listed in literature. The linear elements for the optical components were calculated and the dy-namical parameters for the physical AD pair were determined. A small relative motion with very low significance was detected for AD. This motion is compatible with a Keplerian motion and we conclude that AD components could be gravitationally bound.