Caltech Logo

Astronomy Colloquium

Wednesday, March 13, 2019
4:00pm to 5:00pm
Add to Cal
Cahill, Hameetman Auditorium
The Formation of Close Binary Stars and Planets
Maxwell Moe, University of Arizona, Tucson,

The formation and orbital migration of close binaries and hot Jupiters remain a mystery. The majority of very close binaries have outer tertiary companions, suggesting Kozai-Lidov oscillations coupled with tidal friction play an important role in their dynamical evolution. However, close pre-main-sequence binaries are ubiquitous, indicating most close binaries migrated within a few Myr while there was still dissipative gas in the primordial disk. I will overview a new population synthesis model that incorporates more realistic initial conditions and a novel tidal mechanism to explain the formation of close binaries and hot Jupiters during the pre-main-sequence phase. Although planets may favor metal-rich hosts, recent observations demonstrate the close binary fraction dramatically increases toward lower metallicities. I will discuss five different observational techniques that corroborate this metallicity trend, and will outline a fragmentation model that reproduces the observations. I will conclude by highlighting how close binaries suppress the formation of close (S-type) planets. Close binaries therefore substantially bias planet occurrence rates and the inferred trends with respect to host mass and metallicity.

For more information, please contact Judy McClain by phone at 626-395-4970 or by email at [email protected].