Astrophysical Laboratories and Advanced Imaging Techniques for Testing Stellar Models: Eclipsing Binaries, High Contrast Imaging, and Optical Interferometry

Abstract

In chapter 1, we determine the masses, radii and temperatures of the eclipsing binary V578 Mon, a detached system of two early B-type stars in the Rosette Nebula, to better than 5% accuracy. We compare these measurements to the stellar models of the Geneva, Utrecht and Granada group. We find all three sets of models marginally reproduce the absolute dimensions of both stars. However - there are some apparent discrepancies, and the Utrecht models worked best. We also compute the combined internal structure constants for V578 Mon. We find that the predicted internal structure constants of the Granada models fully agrees with our observations. In chapter 2, we present the results of a Hubble Space Telescope survey of the lowest mass brown dwarfs in the Pleiades. These objects represent the predecessors to T-dwarfs in the field. Using a new PSF-fitting technique, we are able to probe to 30 milliarcseconds, better than 2× the HST diffraction limit. We did not find any companions to our targets. Our survey is the first to attain the high angular resolution needed to resolve brown dwarf binaries in the Pleiades at separations that are most common in the field population. We constrain the binary frequency to be <26% at 2σ. This binary frequency is consistent with both younger and older brown dwarfs in this mass range and with brown dwarf formation models. Visible-light long baseline interferometry holds the promise of advancing a number of important applications in fundamental astronomy, including the direct measurement of the angular diameters and oblateness of stars, and the orbits of binary and multiple star systems. To advance, the field requires instruments capable of combining light from 6 telescopes simultaneously. In chapter 3, we present the Visible Imaging System for Interferometric Observations at NPOI (VISION) is a new visible light beam combiner for the Navy Precision Optical Interferometer (NPOI) that coherently combines light from up to six telescopes simultaneously. We detail the commissioning of VISION with laboratory and on-sky tests. We provide a new set of corrections for the power spectrum and bispectrum when using EMCCDs.