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Detection of a NEPTUNE-mass planet in the $ρ^{1}$ Cancri system using the Hobby-Eberly Telescope

Barbara E. McArthur·Michael Endl·William D. Cochran·G. Fritz Benedict·Debra A. Fischer·Geoffrey W. Marcy·R. Paul Butler·Dominique Naef·Michel Mayor·Diedre Queloz·Stephane Udry·Thomas E. Harrison
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Abstract

We report the detection of the lowest mass extra-solar planet yet found around a Sun-like star - a planet with an \msini of only 14.21 $\pm$ 2.91 Earth masses in an extremely short period orbit (P=2.808 days) around $ρ^{1}$ Cancri, a planetary system which already has three known planets. Velocities taken from late 2003-2004 at McDonald Observatory with the Hobby-Eberly Telescope (HET) revealed this inner planet at 0.04 AU. We estimate an inclination of the outer planet $ρ^{1}$ Cancri d, based upon {\it Hubble Space Telescope} Fine Guidance Sensor (FGS) measurements. This inclination suggests an inner planet of only 17.7 $\pm$ 5.57 Earth masses, if coplanarity is assumed for the system.

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Barbara E. McArthur, Michael Endl, William D. Cochran, G. Fritz Benedict, Debra A. Fischer, Geoffrey W. Marcy, R. Paul Butler, Dominique Naef, Michel Mayor, Diedre Queloz, Stephane Udry, Thomas E. Harrison. 2004-08-31. Detection of a NEPTUNE-mass planet in the $ρ^{1}$ Cancri system using the Hobby-Eberly Telescope. https://doi.org/10.1086/425561

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