Demographics of the Youngest Protostars and their Disks

Sheehan Patrick D, Evanston IL

Investigators

Abstract

Patrick Sheehan is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to conduct a program of research and education at Northwestern University. He will study the structures and properties of disks, which are formed when clouds of gas and dust in space collapse to form protostars. Observational evidence suggests that planets and their precursors are formed very early during the onset of star formation, and the results from this project will allow astronomers to understand just how soon planet formation begins. Along with this research, Sheehan will conduct a summer educational program designed to provide experience in programming, data analysis, and astronomical research to high school students. Recent observations of substructures in protoplanetary disks surrounding nearly every 1-5 Myr-old pre-main sequence star suggest that these disks may already have undergone a significant amount of planet or planetesimal formation. To understand the initial conditions before significant dust processing or planet formation has occurred, this project will investigate the structures of younger disks (< 1 Myr old) and their central protostars using observations done at very high angular resolution from centimeter to submillimeter wavelengths. The observations will include every known protostellar disk in the Taurus star-forming region, enabling Sheehan to place constraints on the structure of gas and dust and on the growth of early dust grains. Sheehan will also use high-resolution imaging to study a known population of young disks in the Orion star-forming region with substructures possibly related to early planet formation. Finally, he will directly measure the dynamical masses of young protostars to place these disks within the context of their stars and place robust constraints on pre-main sequence evolutionary tracks. This project will generate the largest sample of directly measured protostellar masses, and the measurements will provide information on how disk mass depends on protostellar mass. The resulting comprehensive picture will advance our understanding of the potential for planet formation in disks, as well as the precise location of the forming planets. 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.