Merging Giant-Star Asteroseismology with the Fate of Extrasolar Planetary Systems

An RAS Specialist Discussion Meeting

London, UK, March 9th 2018

Although stars spend a significant fraction of their lives on the main sequence, they undergo their most dramatic physical changes during post-main-sequence evolution. The fates of their planetary systems may be similarly violent. Hence, the simultaneous study of both planets and stars along the latter's subgiant and giant-branch phases is capable of providing constraints on tidal, mass-loss and radiative processes, as well as invaluable insight into the processes of planet formation and evolution.

Over 100 planets and several debris discs are now known to orbit subgiant and giant stars, thereby providing constraints on their past and future evolution. Further, the absence of planets close to other giant stars signifies destructive processes at work. A critical restriction on the nature and timescale of these destructive processes is stellar age, a previously poorly constrained property.

Fortunately, new insights on the theory of stellar evolution and stellar interiors physics have been made possible by asteroseismology, the study of stars by the observation of their natural, resonant oscillations. Asteroseismology is proving to be particularly significant for the study of evolved stars, namely, subgiant and red-giant stars. These stars exhibit solar-like oscillations. The information contained in solar-like oscillations allows fundamental stellar properties (e.g., mass, radius and age) to be precisely determined, while also allowing the internal stellar structure to be constrained to unprecedented levels. As a result, asteroseismology is quickly maturing into a powerful tool whose impact is being felt more widely across different domains of astrophysics. A noticeable example is the synergy between asteroseismology and exoplanetary science.

During this RAS Specialist Discussion Meeting we will review our current understanding of the evolution and fate of extrasolar planetary systems during the subgiant and giant stellar evolutionary phases. Furthermore, by bringing together members of the leading UK exoplanets and asteroseismology communities, we expect to establish a roadmap for the effective and synergetic exploitation of the wealth of space-based data that will soon become available to both communities. In this regard, we highlight the upcoming NASA TESS and ESA CHEOPS satellites, both with launches scheduled for 2018, thus stressing the timeliness of this meeting.