The HARPS search for southern extra-solar planets. François Bouchy, M. Mayor, C. Lovis, S. Udry, W. Benz, Jean-Loup Bertaux, X. Delfosse, C. Mordasini, F. Pepe, D. Queloz, et al.
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François Bouchy, M. Mayor, C. Lovis, S. Udry, W. Benz, et al.. The HARPS search for southern extra-solar planets.: XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD47 186 and HD181 433. Astronomy and Astrophysics - A&A, EDP Sciences, 2009, 496 (2), pp.527-531. 10.1051/0004-6361:200810669. hal-00370485
HAL Id: hal-00370485 https://hal.archives-ouvertes.fr/hal-00370485 Submitted on 12 Jul 2020
HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. A&A 496, 527–531 (2009) Astronomy DOI: 10.1051/0004-6361:200810669 & c ESO 2009 Astrophysics
The HARPS search for southern extra-solar planets ,
XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD 47 186 and HD 181 433
F. Bouchy1, M. Mayor2,C.Lovis2,S.Udry2,W.Benz3, J.-L. Bertaux4, X. Delfosse5, C. Mordasini3, F. Pepe2,D.Queloz2, and D. Segransan2
1 Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France e-mail: [email protected] 2 Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland 3 Physikalisches Institut Universitat Bern, Sidlerstrasse 5, 3012 Bern, Switzerland 4 Service d’Aéronomie du CNRS, BP 3, 91371 Verrières-le-Buisson, France 5 Laboratoire d’Astrophysique, Observatoire de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble, Cedex 9, France Received 24 July 2008 / Accepted 20 November 2008 ABSTRACT
We report on the detection of two new multiple planet systems orbiting solar-like stars HD 47 186 and HD 181 433. The first system contains a hot Neptune of 22.78 M⊕ with a 4.08-day period and a Saturn of 0.35 MJUP with a 3.7-year period. The second system contains a Super-Earth of 7.5 M⊕ with a 9.4-day period, a 0.64 MJUP with a 2.6-year period, and a third companion of 0.54 MJUP with a period of about 6 years. These detections increase to 20 the number of close-in low-mass exoplanets (below 0.1 MJUP) and strengthen the fact that 80% of these planets are in multiple planetary systems. Key words. stars: planetary systems – techniques: radial velocities – stars: individual: HD 47 186 – stars: individual: HD 181 433
1. Introduction now leading to an increasing list of close-in low-mass exoplan- ets, which will improve our knowledge of the planet distribution The HARPS spectrograph based on the 3.6-m ESO telescope in the mass-period diagram and allow comparisons with theoret- at La Silla Observatory has been in operation since 2003. ical predictions. Furthermore, this increasing number of close-in The HARPS consortium started 5 years ago as an ambitious low-mass planets stimulates dedicated photometric follow-up to and comprehensive Guaranteed Time Observations (GTO) pro- detect transiting Neptunes such as GJ436b (Gillon et al. 2007). gram of high-precision systematic searches for exoplanets in the Indeed we expect statistically that 5–10% of these close-in low- ff Southern sky (Mayor et al. 2003, 2009). Significant e orts were mass exoplanets offer the appropriate configuration for transiting made to search for very low-mass planets. Our consortium have their parent stars. In that case, a direct measurement of the plan- been assigned 50% of the GTO time on HARPS since 2003 to etary radius as well as the exact mass will be provided. In this monitor about 200 nearby non-active stars. Due to a radial veloc- paper, we present the discovery of two new multiple planet sys- −1 ity accuracy of higher than 1 m s (Pepe et al. 2004; Lovis et al. tems, including one hot Neptune and one Super-Earth orbiting 2007), HARPS has discovered several Neptune-mass and Super- the stars HD 47 186 and HD 181 433, respectively. Earth exoplanets around solar-type stars (Santos et al. 2004; Udry et al. 2006; Lovis et al. 2006;Meloetal.2008; Mayor et al. 2009) and M dwarfs (Bonfils et al. 2005;Udryetal.2007a; 2. Parent-star characteristics of HD 47 186 Bonfils et al. 2007, Forveille et al. 2009). Such efficiency orig- and HD 181 433 inates in the following factors: 1) a careful and frequent moni- toring of instrumental performances; 2) a continuous improve- The basic photometric and astrometric properties of HD 47 186 ment of the data reduction software (e.g. Lovis & Pepe 2007); and HD 181 433 were taken from the Hipparcos catalogue 3) a dedicated and careful observing strategy to deal with stellar (ESA 1997). Accurate spectroscopic stellar parameters of the seismic noise (e.g. Bouchy et al. 2005); 4) a long-duration mon- HARPS GTO “high-precision” program were determined by itoring of non-active stars; and 5) an accumulation of measure- Sousa et al. (2008) using high-quality, high-resolution, and / ments to identify multi-planetary systems. Our large program is high-S N HARPS spectra. Stellar parameters for HD 47 186 and HD 181 433 are summarized in Table 1.