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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.
The author(s) of this abstract have provided an email address for comments about the abstract: wdc@astro.as.utexas.edu
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.