An Unexpected Planet Population: How Did Super-Earths Acquire Their Currently Observed Properties?

Wolfgang Angie, Santa Cruz CA

Investigators

Abstract

Angie Wolfgang is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at The Pennsylvania State University. She will be studying extrasolar planets that are up to four times larger than Earth and that orbit their stars faster than Mercury orbits the Sun. No such planets exist in our Solar System, yet they are extremely common, so it is not well understood how they formed. Thankfully, the Kepler Mission provides thousands of such planets to analyze. Wolfgang aims to better understand the characteristics and possible histories of these planets by adopting a big-picture approach which incorporates the available yet incomplete information about each. In particular, she will combine physical models of different evolutionary processes with a sophisticated population-wide statistical framework to identify the most probable ways that these planets came to have their current compositions and orbits. For her education efforts, Wolfgang will develop and implement interactive, hands-on activities for a multicultural community of Penn State freshmen who are interested in pursuing careers in science and engineering. Because these activities more genuinely reflect the process of scientific inquiry and discovery than most college laboratory assignments and coursework, these students will gain valuable experience with the skills needed to do cutting-edge research and will begin to develop confidence and an identity as a scientist. The Kepler Mission has demonstrated that sub-Neptune-sized planets are ubiquitous in our Galaxy, yet it is a challenge to understand their compositional structure and to explain their close-in orbits. Progress on these and other topics in planet formation and evolution theory has been challenged by large measurement uncertainties as well as significant detection biases and selection effects in the detected Kepler population. Wolfgang will meet this need for a more data-driven approach by coupling a sophisticated hierarchical Bayesian framework to physical models and theoretical simulations of important evolutionary processes. In particular, she will investigate the compositional and orbital evolution of super-Earths and sub-Neptunes, quantifying the degree to which photoevaporation and Kozai-Lidov oscillations have affected these planets' properties since the dispersal of their protoplanetary disks. In doing so, Wolfgang will be able to supply robust end conditions to planet formation theory and accelerate theoretical understanding of the dominant processes during planet formation. Wolfgang will mentor female astrophysics undergraduate and graduate students, advise undergraduate research projects, serve as an instructor for the Penn State Summer School in Statistics for Astronomers, and implement inquiry-based activities to encourage the students in these programs - who often are members of minority groups underrepresented in the sciences - to develop scientific thinking skills and an identity as a scientist.