Stellar and planetary systems at late stages of stellar evolution
Georg August University Göttingen
The number of known planetary systems beyond the main sequence are sparse so far, yet they are relevant for mapping the full parameter space of planet formation and evolution. The pulsation timing and the eclipse timing methods are highlighted as particularly suitable approaches to search for planets around evolved stars. Both extrasolar planet searches and asteroseismology, while at the same time strongly relying on modeling, are very much observationally driven at the moment. Their increasing synergies are partly thanks to the convergence on the instrumentational side. This applies to ground-based as well as, to an even higher extent, to space-based surveys. The EXOTIME program, conducted from ground-based telescopes, covers a niche that exploits stellar pulsations of a particular type of evolved stars to search for planets and low-mass/substellar companions with the timing method, as well as to use the pulsations to characterize the host stars. One of EXOTIME's main science drivers is the after-the-fact investigation of star-planet interactions during the red giant phase, an evolutionary stage where an evolving host star and some of its planets are likely to interact in a way that may even imply direct consequence for the structure of the star, and certainly for the planet. The specific experience from the on-going EXOTIME observations and analysis can be drawn upon to extend the synthesis of pulsation timing for planet searches, and pulsation analysis for host star characterization, to the space-based KEPLER data. Rapidly and strictly coherently pulsating stars such as those used in EXOTIME are very rare even in the vast amounts of KEPLER data sets that are now continuously coming in. The unique coverage and signal-to-noise ratio of the KEPLER data, however, will allow to explore an extension of the timing method to other types of variable stars. Its application can also encompass variability due to eclipses instead of, or in addition to, pulsations. A broadening in scope will in the long term also be useful to take advantage of the data from the proposed future PLATO mission, with its ambitious goal of asteroseismic, photometric and (using ground-based follow-up observations) spectroscopic full characterization of systems.
Date: Friday, 18 February 2011 Time: 14:00 Where: Université de Montréal Pavillon Roger-Gaudry, Local Z-300 Contact: Pierre Bergeron