Circumstellar Disk Evolution and Implications for Planet Formation in the Binary Environment

While recent surveys suggest that planet formation is universal, circumstellar disks, which provide the raw material for planet formation, are detected less often in young binary star systems, particularly in close binaries. Given that 1/3 to 1/2 of all stars occur in binary systems, the question naturally arises as to how the variable irradiation and gravitational fields in these systems influence the properties (and survivability) of circumstellar disks and the planets that form therein.

This research program will use data covering a wide wavelength range to advance our understanding of the structure and evolution of circum-stellar disks for a sample of both close and widely separated binaries. This program will support a post-doctoral researcher as well as several broad efforts to stimulate interest in the physical sciences among historically underrepresented communities.

The principal investigator proposes a study of young binary stars over a wide range of separations (from a few to several hundred A.U.) to characterize (1) the impact membership in a multiple system has on circumstellar disk formation, structure, and evolution, and (2) why circumstellar disk evolution appears uneven in some wide binary systems despite what one might have expected to be inconsequential dynamical effects of the companion star. Wider pairs will provide the basis of a more nuanced study of circumstellar disk behavior in general, while disk characteristics in closer pairs will offer insight into not only disk but also binary formation models.

To carry out these goals, the PI will employ high-resolution infrared spectroscopy, high-angular resolution optical/infrared imaging, time series photometry - both ground-based and with NASA’s K2 - to determine rotation periods, as well as direct imaging of circumstellar disks through their sub-millimeter dust emission with ALMA. The analysis of these data will lead to a comprehensive picture of both the formation and evolution of circumstellar disks in close and wide binaries viewed as a function of their stellar and binary properties.

Additionally, by combining individual rotation periods and values for the projected rotation it may ultimately be possible to measure the stellar inclination in binaries. Misaligned stellar rotation axes may provide clues to dynamical processes behind disk evolution.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.