Hot Chromospheres and Flares on Ultracool Dwarfs

Mittwoch, 20. Dezember 2017, 14:00 - 15:00
Veranstaltungsort* library
 Ultracool (late-M and L) dwarfs include both the least massive stars and warmest brown dwarfs. While their photospheres are characterized by very cool temperatures, the presence of strong surface magnetic fields heats their chromospheres. Chromospheric activity (as traced by Halpha emission) is common on ultracool dwarfs, but is very weak, likely originating from less than 0.01% of the surface. In addition to quiescent emission, these magnetically active objects can produce dramatic flares, including several >6 magnitude flares observed as part of Kepler K2 and the All Sky Automated Survey for Supernovae. These flares may be more common than previously thought, and their strong UV radiation may place strong limits on the habitability of exoplanets in tight orbits around faint hosts. I will discuss my ongoing work to understand the quiescent and flaring magnetic activity at the stellar/sub-stellar boundary.

: Dr. Sarah J. Schmidt, AIP