Volume 621, January 2019
|Number of page(s)||12|
|Section||Planets and planetary systems|
|Published online||15 January 2019|
The GAPS Programme with HARPS-N at TNG
Dipartimento di Fisica, Università degli Studi di Torino,
Via Pietro Giuria 1,
2 INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
3 INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123, Catania, Italy
4 Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
5 INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122, Padova, Italy
6 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
7 Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
8 INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy
9 INAF – Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34143 Trieste, Italy
10 INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
11 Fundación Galileo Galilei – INAF, Rambla José Ana Fernandez Pérez 7, 38712 Breña Baja, TF, Spain
12 INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131, Napoli, Italy
13 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
14 Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
15 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
16 INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
17 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Accepted: 17 November 2018
Context. Statistical studies of exoplanets have shown that giant planets are more commonly hosted by metal-rich dwarf stars than low-metallicity stars, while no such correlation is evident for lower mass planets. The search for giant planets around metal-poor stars and the estimate of their occurrence fp is an important element in providing support to models of planet formation.
Aims. We present results from the HARPS-N search for giant planets orbiting metal-poor (− 1.0 ≤[Fe/H] ≤−0.5 dex) stars in the northern hemisphere, complementing a previous HARPS survey on southern stars in order to update the estimate of fp.
Methods. High-precision HARPS-N observations of 42 metal-poor stars were used to search for planetary signals to be fitted using differential evolution Markov chain Monte Carlo single-Keplerian models. We then joined our detections to the results of the previous HARPS survey on 88 metal-poor stars to provide a preliminary estimate of the two-hemisphere fp.
Results. We report the detection of two new giant planets around HD 220197 and HD 233832. The first companion has Msin i = 0.20−0.04+0.07 MJup and an orbital period of 1728−80+162 days, and for the second companion, we find two solutions of equal statistical weight with periods of 2058−40+47 and 4047−117+91 days and minimum masses of 1.78−0.06+0.08 and 2.72−0.23+0.23 MJup, respectively. Joining our two detections with the three from the southern survey, we obtain a preliminary and conservative estimate of the global frequency of fp = 3.84 −1.06+2.45% for giant planets around metal-poor stars.
Conclusions. The two new giant planets orbit dwarf stars at the metal-rich end of the HARPS-N metal-poor sample. This corroborates previous results that suggested that giant planet frequency is still a rising function of the host star [Fe/H]. We also note that all detections in the overall sample are giant long-period planets.
Key words: techniques: radial velocities / methods: data analysis / planetary systems / stars: abundances / stars: individual: HD 220197 / stars: individual: HD 233832
Based on observations made with the HARPS-N spectrograph on the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma (Spain) by the INAF – Fundación Galileo Galilei (Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias).
RV data (Table 5) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/621/A110
© ESO 2019
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