The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD 4113 and HD 156846

O. Tamuz, D. Ségransan, S. Udry, M. Mayor, P. Eggenberger, D. Naef, F. Pepe, D. Queloz, N. C. Santos, B.-O. Demory, P. Figuera, M. Marmier, G. Montagnier

Abstract
We report the detection of two very eccentric planets orbiting HD 4113 and HD 156846 with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope at La Silla. The first planet, HD 4113 b, has minimum mass of msin i = 1:6  0:2 MJup, a period of P = 526:59  0:21 days and an eccentricity of e = 0:903  0:02. It orbits a metal rich G5V star at a = 1:28AU which displays an additional radial velocity drift of 28 ms^1/yr observed during 8 years. The combination of the radial-velocity data and the non-detection of any main sequence stellar companion in our high contrast images taken at the VLT with NACO/SDI, characterizes the companion as a probable brown dwarf or as a faint white dwarf. The second planet, HD 156846 b, has minimum mass of msin i = 10:45  0:05 MJup, a period of P = 359:51  0:09 days, an eccentricity of e = 0:847  0:002 and is located at a = 1:0 AU from its parent star. HD156846 is a metal rich G0 dwarf and is also the primary of a wide binary system (a > 250AU, P > 4000 years). Its stellar companion, IDS 17147-1914 B , is a M4 dwarf. The very high eccentricities of both planets can be explained by Kozai oscillations induced by the presence of a third object.

Astronomy and Astrophysics
Volume 480, Page L33
March 2008

DOI: 10.1051/0004-6361:20078737
ADS Bibliographic code: 2008A%26A...480L..33T