EDP Sciences
Free access
Volume 398, Number 2, February I 2003
Page(s) L19 - L23
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021846

A&A 398, L19-L23 (2003)
DOI: 10.1051/0004-6361:20021846


Evidence of a sub-stellar companion around HD 47536

J. Setiawan1, A. P. Hatzes2, O. von der Lühe1, L. Pasquini3, D. Naef4, L. da Silva5, S. Udry4, D. Queloz4 and L. Girardi6

1  Kiepenheuer-Institut für Sonnenphysik, Freiburg(Brsg), Germany
2  Thüringer Landessternwarte Tautenburg, Tautenburg, Germany
3  European Southern Observatory, Garching bei München, Germany
4  Observatoire de Genève, Geneva, Switzerland
5  Observatório Nacional, Rio de Janeiro, Brazil
6  Osservatorio Astronomico di Trieste, Trieste, Italy

(Received 5 November 2002 / Accepted 15 December 2002 )

We report evidence of a low-mass companion around the K1III giant star HD 47536. This star belongs to our sample of 83 subgiant and giant stars studied for their radial velocity variations using the FEROS spectrograph at the 1.52 m-ESO telescope on La Silla. We find that the radial velocity of HD 47536 exhibits a periodic variation of about 712 days with a semi-amplitude of 113  ${\rm m\,s}^{-1}$. These variations are not accompanied by variations in either Ca II emission or in the spectral line shapes. A Keplerian orbit due to a sub-stellar companion is thus the most viable explanation for the radial velocity variation. Assuming a moderate stellar mass of $m_{1}= 1.1{-}3.0~M_{\odot}$ we obtain a minimum mass for the companion of  $m_{2} \sin{i}= 5.0{-}9.7~M_{\rm Jup}$, an orbital semi-major axis of 1.6-2.3 AU, and an eccentricity of e=0.2.

Key words: stars: late-type -- stars: individual: HD 47536 -- technique: radial velocities -- stars: planetary systems

Offprint request: J. Setiawan, setiawan@kis.uni-freiburg.de

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© ESO 2003