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Centro de Astrofísica da Universidade do Porto

The frequency of giant planets around metal-poor stars

A. Mortier, N. C. Santos, A. Sozzetti, M. Mayor, D. W. Latham, X. Bonfils, S. Udry

Abstract.
The discovery of around 700 extrasolar planets, so far, has lead to the first statistics concerning extrasolar planets. The presence of giant planets seems to depend on stellar metallicity and mass. For example, they are more frequent around metal-rich stars, with an exponential increase in planet occurrence rates with metallicity. In this regard, two samples of very metal-poor stars have been analyzed to see if giant planets are indeed rare around these objects. In this unique sample, radial velocity datasets were obtained with two different spectrographs (HARPS and HIRES). Taking the detection limits for these data into account, trustworthy numbers for the planet frequency can be obtained.
The results of this study point out that giant planet frequency is indeed a strong function of metallicity. However, the frequencies are most likely higher, in the low metallicity end, than previously thought. In this talk, I will present the datasets, the methods, and most importantly, the results we have found.

Planet Formation and Evolution 2012
8th Conference on Formation and Evolution of Planetary Systems
München, Germany
September 2012

Type: Oral comunication

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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