Institute of Astronomy

Observational Insight into the Effect of Stellar Evolution on Exoplanet Systems

SpeakerTalk DateTalk Series
Kevin Schlaufman28 July 2014Across HR 2014 Talks


Planets around stars on the red giant branch differ from planets around main-sequence stars in two ways: they are much more likely to be on circular orbits, and much less likely to be found with orbital periods less than 100 days. Previously, these differences have been attributed to stellar mass, as it was thought that the evolved stars that were searched for planets were systematically more massive than the main-sequence stars. I will show that the Galactic space motions of the evolved host stars demand that on average they be similar in mass to main-sequence FG type planet-hosts. Therefore, the two samples differ only in age, and provide a glimpse of the same exoplanet population both before and after the host star begins to evolve into a giant. Consequently, the lack of hot Jupiters around stars at the base of the red giant branch is clear evidence that such planets are tidally destroyed. Questions remain, though, about the interpretation of other reported differences between the planet populations around evolved stars and main-sequence stars, such as their period and eccentricity distributions and overall occurrence rates.