An Upper Limit to the Mass of the Radial Velocity Companion to ρ1 Cancri
Han, Inwoo; Gatewood, George; Black, David C.; McGrath, Melissa A.; Nelan, Edmund; Noll, Keith; Schultz, Al; Lubow, Stephen; Stepinski, Tomasz F.; Targett, Thomas
United States, South Korea, United Kingdom
Abstract
Doppler spectroscopy of ρ1 Cnc has detected evidence of a companion with an orbital period of 14.65 days and a minimum mass of 0.88 Jupiter masses. Astrometric observations performed with the Hubble Space Telescope Fine Guidance Sensor 1r using a novel observing technique have placed an upper limit on the astrometric reflex motion of ρ1 Cnc in a time period of only 1 month. These observations detected no reflex motion induced by the 14.65 day period radial velocity companion, allowing us to place a 3 σ upper limit of ~0.3 mas on the semimajor axis of this motion, ruling out the preliminary Hipparcos value of 1.15 mas. The corresponding upper limit on the true mass of the companion is ~30 MJ, confirming that it is a substellar object.