EDP Sciences
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Volume 470, Number 2, August I 2007
Page(s) 721 - 726
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20077361

A&A 470, 721-726 (2007)
DOI: 10.1051/0004-6361:20077361

The HARPS search for southern extra-solar planets

IX. Exoplanets orbiting HD 100777 , HD 190647 , and HD 221287
D. Naef1, 2, M. Mayor2, W. Benz3, F. Bouchy4, G. Lo Curto1, C. Lovis2, C. Moutou5, F. Pepe2, D. Queloz2, N. C. Santos2, 6, 7, and S. Udry2

1  European Southern Observatory, Casilla 19001, Santiago 19, Chile
    e-mail: dnaef@eso.org
2  Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
3  Physikalisches Institut Universität Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
4  Institut d'Astrophysique de Paris, UMR7095, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
5  Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, 13376 Marseille 12, France
6  Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
7  Centro de Geofísica de Évora, Rua Romão Ramalho 59, 7002-554 Évora, Portugal

(Received 26 February 2007 / Accepted 11 April 2007 )

Context. The HARPS high-resolution high-accuracy spectrograph was made available to the astronomical community in the second half of 2003. Since then, we have been using this instrument for monitoring radial velocities of a large sample of Solar-type stars ($\simeq$1400 stars) in order to search for their possible low-mass companions.
Aims. Amongst the goals of our survey, one is to significantly increase the number of detected extra-solar planets in a volume-limited sample to improve our knowledge of their orbital elements distributions and thus obtain better constraints for planet-formation models.
Methods.Radial-velocities were obtained from high-resolution HARPS spectra via the cross-correlation method. We then searched for Keplerian signals in the obtained radial-velocity data sets. Finally, companions orbiting our sample stars were characterised using the fitted orbital parameters.
Results. In this paper, we present the HARPS radial-velocity data and orbital solutions for 3 Solar-type stars: HD 100777 , HD 190647 , and HD 221287 . The radial-velocity data of HD 100777 is best explained by the presence of a 1.16 $M_{\rm Jup}$ planetary companion on a 384-day eccentric orbit (e = 0.36). The orbital fit obtained for the slightly evolved star HD 190647 reveals the presence of a long-period (P = 1038 d) 1.9 $M_{\rm Jup}$ planetary companion on a moderately eccentric orbit (e = 0.18). HD 221287 is hosting a 3.1 $M_{\rm Jup}$ planet on a 456-day orbit. The shape of this orbit is not very well-constrained because of our non-optimal temporal coverage and because of the presence of abnormally large residuals. We find clues that these large residuals result from spectral line-profile variations probably induced by processes related to stellar activity.

Key words: stars: individual: HD 100777 -- stars: individual: HD 190647 -- stars: individual: HD 221287 -- stars: planetary systems -- techniques: radial velocities

© ESO 2007

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