This thesis falls into the general category of studies of the outer layers of stars on the mid to lower main sequence. It deals specifically with the properties of the convective envelopes of F-type stars, and how these relate to mixing mechanisms in their interiors and energy deposition in their atmospheres. The observational context of the study

We present an analysis of time correlations between measurements of solar radius, neutrino flux data, and acoustic mode frequency shifts. We find significant anticorrelation of the first two quantities with the last one. Variations are found over time scales of order the 11 yr solar cycle and at shorter time scales. The shorter periods, of order 1

Analytical approximations and 2D hydrodynamical simulations are used to examine the interaction of supernova fragments with the internal structure of large multisupernova remnants (MSRs). The fragments are thermalized by reverse shocks generated in the interaction with the MSR interior, which is assumed to be hot and rarefied. The evolution is

IAUC 5738 available at Central Bureau for Astronomical Telegrams.

IAUC 5754 available at Central Bureau for Astronomical Telegrams.

Not Available