36th DPS Meeting, 8-12 November 2004
Session 42 Extrasolar Planets
Oral, Friday, November 12, 2004, 8:30-10:00am, Clark

## [42.01] New Planets Detected with the Hobby-Eberly Telescope

W. D. Cochran, M. Endl, B. E. McArthur (UT Austin)

The High Resolution Spectrograph on the Hobby-Eberly Telescope is now routinely producing stellar radial velocities with a precision of 2-3 meters/second. This velocity precision, coupled with queue-mode observing, has allowed us to detect planetary companions to two stars: HD\,37605 and \rho1\,Cancri. The companion to HD\,37605 has a minimum mass of 2.84 Jupiter masses. The planet is in a 54.23 day orbit of e = 0.737. The queue-scheduled operation of the Hobby-Eberly Telescope enabled us to discovery of this relatively short-period planet with a total observation time span of just two orbital periods. We have also discovered a fourth planet in orbit around \rho1\,Cancri. This planet has a 2.81 day orbital period, and a minimum mass of 14.21 Earth masses. This is the lowest m \sin i of all of the extrasolar planets yet found. Analysis of Hubble Space Telescope~ Fine Guidance Sensor measurements together with all available ground-based radial velocity data gives a probable inclination for the outer planet \rho1\,Cancri d of 53\circ. Assuming coplanarity for all of the planets in the system, we then get a most probable mass for the new inner planet of 17.7 Earth masses. This planet may be a missing link'' in the planetary formation scenarios - a close-in Neptune-mass rocky core of a gas giant.