UAH Distinguished Speaker Series Seminar
The Growth of Cosmic Dust Bunnies: How to Build a Solar System
Dr. Lorin S. Matthews
Department of Physics
Baylor University
Summary: The Hubble and Kepler Space Telescopes have discovered thousands of planets orbiting other stars, many of which are quite different from our own. As humans, our primary question is if other Earth-like planets exist which can support life. As scientists, we are interested in the physical processes which influence the formation of various types of planets: rocky bodies or gas giants, “hot Jupiters” or frozen snowballs.
Planet formation is actually very efficient on astronomical time scales, the process taking only ten million years or so of a star’s multi-billion-year lifetime. After a star is formed from a collapsing cloud of gas and dust, a disk of material orbiting the star remains. Planets form from the material within this disk, starting with micron-sized dust grains sticking together to form centimeter-sized dust bunnies. How these fluffy aggregates grow to solid rocky bodies big enough to interact with each other gravitationally is not yet understood.
This talk will focus on two factors affecting collisional growth: grain charging and photophoresis. Over large regions of a protoplanetary disk, the gas is weakly ionized the dust grains are exposed to ionizing radiation. This results in dust grains becoming charged. Collisional grain growth is thus slowed by the repulsion of the charged grains, although the charge-dipole interactions can lead to an increased growth rate. The photophoretic force, which occurs due to the interactions of gas particles with an unevenly heated dust grain, tends to push particles away from the star. In addition, it selectively moves solid particles based on their composition (silicate or metallic) and structure. This not only generates collision velocities between grains of different sizes, but also sorts the dust in protoplanetary disks (PPDs) by composition.
About the speaker: Dr. Lorin S. Matthews is a professor at the Department of Physics, and Associate Director of the Center for Astrophysics, Space Physics & Engineering Research (CASPER) in Baylor University. She earned her B.S. and Ph.D. degrees in 1994 and 1998 from Baylor University. From 1998-2000 she was employed as an engineer at Raytheon Aircraft Integrations Systems, where her main project was vibroacoustics analysis for NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA). In 2000, she returned to Baylor as a lecturer in the Physics Department and Baylor Interdisciplinary Core and Senior Research Scientist with CASPER (2000-2006). Dr. Matthews is a recipient of the NSF CAREER award and is a Kavli Fellow. She has published 56 papers in print journals and books and has over 200 published abstracts and reviewed proceedings.
Refreshments will be served at 12:45pm
Please contact the host faculty Babak Shotorban babak.shotorban@uah.edu at the Department of Mechanical and Aerospace Engineering if you have questions regarding this event.
