Monday, June 9 - Plenary Session

Name:  Ilaria Pascucci

Affiliation:  LPL/U Arizona

Title:  The EUV Luminosity from Young Cool Stars: Implications for the Dispersal of Protoplanetary Material

We present a new method to estimate the maximum ionizing (13.6-100eV) luminosity reaching the surface of protoplanetary disks around Cool Stars. In Pascucci et al. (2012) we demonstrated that free-free emission from a fully or partially ionized disk surface is detectable with current instruments and appears as emission in excess to the dust thermal emission at centimeter wavelengths. We now apply this method to 14 stars with ages between a few to ~10Myr for which we have acquired the needed millimeter and centimeter interferometric data to measure the free-free disk emission. We show that the EUV luminosity reaching the disk is below the range of inferred stellar EUV luminosities, by more than an order of magnitude for the older sources in our sample. We discuss our results in the context of the time evolution of stellar EUV luminosities and point out the main implications for the dispersal of protoplanetary material.