The Detectability of Beta Pic-Like Circumstellar Disks Around Nearby Main Sequence Stars

We model scattered light from a circumstellar disk and assess its detectability in ground-based coronagraphic observations of β Pic, Vega, and Fomalhaut. The model is fitted to the observed β Pic disk, adjusted to reflect different physical and observational parameters, and inserted into our raw data, which we subsequently reduce and evaluate for circumstellar nebulosity. We find that the prominence of the β Pic disk is primarily a result of its large scattering cross-section, rather than its edge-on inclination or close proximity to the Sun. Non-detections of disks in our coronagraphic observations of Vega and Fomalhaut imply that the total scattering cross-section of dust around these two nearby stars is not greater than a tenth of β Pic's. Our results indicate that coronagraphic surveys for circumstellar disks around main sequence stars are unlikely to produce positive results unless one order of magnitude improvement is made in the suppression of stellar light.