Reference : The HARPS search for southern extra-solar planets. XIV. Gl 176b, a super-Earth rather th...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/3745
The HARPS search for southern extra-solar planets. XIV. Gl 176b, a super-Earth rather than a Neptune, and at a different period
English
Forveille, T. [Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, Université Joseph Fourier, CNRS, UMR 571, 38041 Grenoble cedex 09, France]
Bonfils, X. [Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal ; Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, Université Joseph Fourier, CNRS, UMR 571, 38041 Grenoble cedex 09, France; Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal]
Delfosse, X. [Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, Université Joseph Fourier, CNRS, UMR 571, 38041 Grenoble cedex 09, France]
Gillon, Michaël mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image >]
Udry, S. [Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland]
Bouchy, F. [Institut d'Astrophysique de Paris, CNRS, Université Pierre et Marie Curie, 98bis Bd. Arago, 75014 Paris, France]
Lovis, C. [Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland]
Mayor, M. [Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland]
Pepe, F. [Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland]
Perrier, C. [Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, Université Joseph Fourier, CNRS, UMR 571, 38041 Grenoble cedex 09, France]
Queloz, D. [Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland]
Santos, N. [Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal]
Bertaux, J*-L [Service d'Aéronomie du CNRS, BP 3, 91371 Verrières-le-Buisson, France]
1-Jan-2009
Astronomy and Astrophysics
EDP Sciences
493
645-650
Yes (verified by ORBi)
International
0004-6361
1432-0746
Les Ulis
France
[en] stars: planetary systems ; stars: late-type ; stars: activity ; stars: low-mass ; brown dwarfs ; stars: starspots ; stars: individual: G1 176
[en] A 10.24-day Neptune-mass planet was recently announced as orbiting the nearby M2 dwarf Gl 176, based on 28 radial velocities measured with the HRS spectrograph on the Hobby-Heberly Telescope. We obtained 57 radial velocities of Gl 176 with the ESO 3.6 m telescope and the HARPS spectrograph, which is known for its sub-m s[SUP]-1[/SUP] stability. The median photon-noise standard error of our measurements is 1.1 m s[SUP]-1[/SUP], significantly lower than the 4.7 m s[SUP]-1[/SUP] of the HET velocities, and the 4-year period over which they were obtained overlaps considerably with the epochs of the HET measurements. The HARPS measurements show no evidence of a signal at the period of the putative HET planet, suggesting that its detection was spurious. We do find, on the other hand, strong evidence of a lower mass 8.4 M_Earth planet, in a quasi-circular orbit and at the different period of 8.78 days. The host star has moderate magnetic activity and rotates on a 39-day period, which we confirm through modulation of both contemporaneous photometry and chromospheric indices. We detect that period, as well, in the radial velocities, but it is well removed from the orbital period and offers no cause for confusion. This new detection of a super-Earth (2 M_Earth < M sin (i) < 10 M_Earth) around an M dwarf adds to the growing evidence that such planets are common around very low-mass stars. A third of the 20 known planets with M sin (i)< 0.1 M_Jup and 3 of the 7 known planets with M sin (i) < 10 M_Earth orbit an M dwarf, in contrast to just 4 of the ~300 known Jupiter-mass planets. Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory under program ID 072.C-0488.
http://hdl.handle.net/2268/3745
10.1051/0004-6361:200810557
http://adsabs.harvard.edu/abs/2009A%26A...493..645F
http://de.arxiv.org/abs/0809.0750

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