SAC Seminar - Sabine Reffert: Planets around Giant Stars

2017.05.15 | Louise Børsen-Koch

Date Thu 18 May
Time 15:15 16:00
Location 1525-323

I will present the latest results from our 12 year Doppler survey of a sample of 374 G and K giant stars, as well as our plans for continuation of the survey. The Doppler survey was carried out at Lick Observatory, and the data supplemented with radial velocities from HARPS and SONG for some particular interesting targets. In the whole sample, we have discovered 17 planets and 26 candidate planets in altogether 35 systems. We have analyzed the planet occurrence rate as a function of metallicity and mass, and find that the planet occurrence rate decreases for stars of higher mass. Also, the period distribution of the planets orbiting giant stars is different from the population of planets found around main-sequence stars, for unknown reasons. Furthermore, we have found several planets in close stellar binary systems, which are particularly interesting for various reasons. We have built our own spectrograph to extend the survey to timescales of about 20-30 years, since we have some excellent systems which show indications for periods of that order.

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