Detection and characterization of circumstellar material with a WFIRST or EXO-C coronagraphic instrument: simulations and observational methods

Abstract

The capabilities of a high (∼10−9 resel−1) contrast narrow-field coronagraphic instrument (CGI) on a space-based WFIRST-C or probe-class EXO-C/S mission are particularly and importantly germane to symbiotic studies of the systems of circumstellar material from which planets have emerged and interact with throughout their lifetimes. The small particle populations in “disks” of co-orbiting materials can trace the presence of planets through dynamical interactions that perturb the spatial distribution of light-scattering debris, which is detectable at visible wavelengths and resolvable with a WFIRST-C or EXO-S/C CGI. Herein, we (1) present the scientific case to study the formation, evolution, architectures, diversity, and properties of the material in the planet-hosting regions of nearby stars; (2) discuss how a CGI under current conception can uniquely inform and contribute to those investigations; (3) consider the applicability of CGI-anticipated performance for circumstellar debris system studies; (4) investigate, through WFIRST CGI image simulations, the anticipated interpretive fidelity and metrical results from specific representative zodiacal debris disk observations; (5) comment on specific observational modes and methods germane to and augmenting circumstellar debris system observations; and (6) present a case for augmenting future CGI instrumentation with the capability to obtain full linear-Stokes imaging polarimetery, which greatly benefits characterization of the material properties of circumstellar dust and exoplanet atmospheres (discussed in other studies).