Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity

Abstract

(abridged) We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 giant stars; an additional 20 giant stars host planet candidates. We investigate the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from about 1 to beyond 3 M_Sun, which is not being explored by main-sequence samples. We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively. We find strong evidence for a planet-metallicity correlation among the secure planet hosts of our giant star sample, in agreement with the one for main-sequence stars. However, the planet-metallicity correlation is absent for our sample of planet candidates, raising the suspicion that a good fraction of them might indeed not be planets. Consistent with the results obtained by Johnson for subgiants, the giant planet occurrence rate increases in the stellar mass interval from 1 to 1.9 M_Sun. However, there is a maximum at a stellar mass of 1.9 +0.1/-0.5 M_Sun, and the occurrence rate drops rapidly for masses larger than 2.5-3.0 M_Sun. We do not find any planets around stars more massive than 2.7 M_Sun, although there are 113 stars with masses between 2.7 and 5 M_Sun in our sample (corresponding to a giant planet occurrence rate < 1.6% at 68.3% confidence in that stellar mass bin). We also show that this result is not a selection effect related to the planet detectability being a function of the stellar mass. We conclude that giant planet formation or inward migration is suppressed around higher mass stars, possibly because of faster disk depletion coupled with a longer migration timescale.

13 pages plus long table appendix, accepted by A&A

References in corpus (21)

• Planet formation around stars of various masses: The snow line and the frequency of giant planets
• Toward a Deterministic Model of Planetary Formation V. Accumulation Near the Ice Line
• A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
• Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
• Distant future of the Sun and Earth revisited
• Evolved stars hint to an external origin of enhanced metallicity in planet-hosting stars
• Planet Engulfment by ~1.5-3 Solar-Mass Red Giants
• Confirmation of the Planet Hypothesis for the Long-period Radial Velocity Variations of Beta Geminorum
• An Eccentric Hot Jupiter Orbiting the Subgiant HD 185269
• Extrasolar planets and brown dwarfs around A-F type stars VI. High precision RV survey of early type dwarfs with HARPS
• A Planetary Mass Companion to the K0 Giant HD 17092
• The properties of planets around giant stars
• Precise radial velocities of giant stars: I. Stable stars
• Precise radial velocities of giant stars. IV. A correlation between surface gravity and radial velocity variation and a statistical investigation of companion properties
• A Substellar Companion to the Intermediate-Mass Giant 11 Com
• Discovery of a planet around the K giant star 4 UMa
• A Planet in a 0.6-AU Orbit Around the K0 Giant HD 102272
• Planet formation around stars of various masses: Hot super-Earths
• The Physical Parameters of the Retired A Star HD185351
• A planetary system and a highly eccentric brown dwarf around the giant stars HIP67851 and HIP97233
• The Discovery of Stellar Oscillations in the K Giant $\iota$ Dra

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