New Observational Constraints on the υ Andromedae System with Data from the Hubble Space Telescope and Hobby-Eberly Telescope
We have used high-cadence radial velocity (RV) measurements from the Hobby-Eberly Telescope with existing velocities from the Lick, Elodie, Harlan J. Smith, and Whipple 60'' telescopes combined with astrometric data from the Hubble Space Telescope Fine Guidance Sensors to refine the orbital parameters and determine the orbital inclinations and position angles of the ascending node of components υ And A c and d. With these inclinations and using M * = 1.31M sun as a primary mass, we determine the actual masses of two of the companions: υ And A c is 13.98+2.3 -5.3 M JUP, and υ And A d is 10.25+0.7 -3.3 M JUP. These measurements represent the first astrometric determination of mutual inclination between objects in an extrasolar planetary system, which we find to be 29fdg9 ± 1°. The combined RV measurements also reveal a long-period trend indicating a fourth planet in the system. We investigate the dynamic stability of this system and analyze regions of stability, which suggest a probable mass of υ And A b. Finally, our parallaxes confirm that υ And B is a stellar companion of υ And A.Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitt Mnchen, and Georg-August-Universität Göttingen.