This award funds an observational program to determine the frequency of close, very low-mass stellar companions to massive stars (those with 3-8 times the mass of the Sun). The results will be used to test the physical limit of the star formation process and to better understand the existence of the so-called "brown dwarf desert" phenomenon, which is used to describe the scarcity of brown dwarfs within about 3-5 astronomical units (AU) of binary stars, and plays a large role in planetary and star formation models. The AU is a unit of length approximately equal to the distance between the Earth and Sun. The results will be used to test star formation models and the nature of sub-stellar companions discovered in brown dwarf and exoplanet searches. They will also provide useful context for extrasolar planet (planets that orbit other stars) imaging surveys. The PI will supervise and mentor two undergraduate students with research internships on this project.
To accomplish this work, the researchers will use extreme adaptive optics systems with the ShaneAO instrument at the Lick Observatory and the Gemini Planet Imager in order to measure the number of extreme mass-ratio binary star systems. The project will comprise two types of targets: one from rich young star clusters within 1 kpc and less than 100 Myr, and another from field stars unassociated with clusters. After the data are reduced, faint companions will be identified from the data after point-spread-functions have been removed from the images of the high-mass stars.
