S. Schmidt (AIP)

Hot Chromospheres and Flares on Cool and Ultracool Dwarfs
Wann Am 26.11.2015 von 14:30 bis 15:30
  • Kolloquium
Wo SH Lecture Hall
Termin übernehmen vCal / iCal

Cool (M) and ultracool (late-M and L) dwarfs include both the least massive stars and warmest brown dwarfs. While their photospheres are characterized by cool (or ultracool) temperatures, the presence of strong surface magnetic fields on many of these objects results in hot chromospheres. On these M and L dwarfs, hot chromospheres are traced by both Halpha emission (in quiescence) and dramatic multi-wavelength flare events. Using detections of Halpha in spectroscopic data primarily from the Sloan Digital Sky Survey, I will examine the changing relationship between activity and age over the M/L spectral sequence. The combination of the strength of these detections with one-dimensional chromosphere models reveals strong changes in the chromospheric heating over the same range of spectral types. I will also discuss the limited flare detections on ultracool dwarfs, placing them in the context of flare observations on cool (early- to mid-M) dwarfs. Flares may prove to be a powerful age indicator in future multi-epoch surveys.