Title: State-of-the-Art Observations and Modeling of Stellar Flares
Abstract: Flares are observed on a wide variety of stellar types, ranging from closely orbiting binary systems consisting of an evolved member (RS CVn's) and young, nearby super-active M dwarfs (dMe's). The timescales and energies of flares span many orders of magnitude and typically far exceed the scales of even the largest solar flares observed. In particular, the active M dwarfs produce an energetic signature in the near-UV and optical continuum, which is often referred to as the white-light continuum. White-light emission has been studied in Johnson UBVR filters during a few large-amplitude flares, and the best emission mechanism that fits the broadband color distribution is a T ~10 4 K blackbody (Hawley & Fisher 1992). Time-resolved blue spectra have revealed a consistent picture, with little or no Balmer jump and a smoothly rising continuum toward the near-UV (Hawley & Pettersen 1991). However, the most recent self-consistent radiative-hydrodynamic (RHD) models, which use a solar-type flare heating function from accelerated, nonthermal electrons, do not reproduce this emission spectrum. Instead, these models predict that the white-light is dominated by Balmer continuum emission from Hydrogen recombination in the chromosphere (Allred et al. 2006). Moreover, Allred et al . (2006) showed that the Johnson colors of the model prediction exhibit a broadband distribution similar to a blackbody with T ~9000 K.