Activity and Planets at the Bottom of the Main Sequence

Low-mass stellar astrophysics has undergone a renaissance over the past two decades. Large surveys have provided statistical samples of these small, dim stars, and the ubiquity of small planets around low-mass stars has reignited interest in their fundamental properties and space weather. In this talk, I will present my work to understand the smallest stars and their stellar and exoplanetary companions. First, I will describe the magnetic activity of M dwarf stars revealed using a large sample of spectroscopically confirmed, high proper motion white dwarf-M dwarf binaries. Using H-alpha chromospheric emission, I examine how M dwarf magnetic activity is affected by the presence of a close white dwarf companion and investigate the role of binary separation. Second, I will present ongoing work to measure precise distances and kinematics of early-type L dwarfs using the 4.3m Discovery Channel Telescope. This sample will be an important complementary sample to Gaia, as we extend Gaia’s reach at the faintest, reddest end of the main sequence. Finally, I will describe our K2 program to search for planets and measure rotation of objects at the M/L transition. Using data obtained thus far, we place constraints on the rocky planet occurrence rate around the smallest stars, including constraints on the rate of occurrence of planets orbiting within the habitable zone.

19 Apr 2018
SHL 215
Julie N. Skinner, PhD, Institute for Astrophysical Research, Boston University