  High-contrast imaging observations of large angular diameter stars enable
complementary science questions to be addressed compared to the baseline goals
of proposed missions like the Terrestrial Planet Finder-Coronagraph, New
World's Observer, and others. Such targets however present a practical problem
in that finite stellar size results in unwanted starlight reaching the
detector, which degrades contrast. In this paper, we quantify the sensitivity,
in terms of contrast, of an internally-occulting, space-based coronagraph as a
function of stellar angular diameter, from unresolved dwarfs to the largest
evolved stars. Our calculations show that an assortment of band-limited image
masks can accommodate a diverse set of observations to help maximize mission
scientific return. We discuss two applications based on the results: the
spectro-photometric study of planets already discovered with the radial
velocity technique to orbit evolved stars, which we elucidate with the example
of Pollux b, and the direct detection of planets orbiting our closest neighbor,
Alpha Centauri, whose primary component is on the main-sequence but subtends an
appreciable angle on the sky. It is recommended that similar trade studies be
performed with other promising internal, external, and hybrid occulter designs
for comparison, as there is relevance to a host of interesting topics in
planetary science and related fields.
