Imaging faint brown dwarf companions close to bright stars with a small, well-corrected telescope aperture

Abstract

We have used our 1.6 m diameter off-axis well-corrected sub-aperture (WCS) on the Palomar Hale telescope in concert with a small inner-working-angle (IWA) phase-mask coronagraph to image the immediate environs of a small number of nearby stars. Test cases included three stars (HD 130948, HD 49197 and HR7672) with known brown dwarf companions at small separations, all of which were detected. We also present the initial detection of a new object close to the nearby young G0V star HD171488. Follow up observations are needed to determine if this object is a bona fide companion, but its flux is consistent with the flux of a young brown dwarf or low mass M star at the same distance as the primary. Interestingly, at small angles our WCS coronagraph demonstrates a limiting detectable contrast comparable to that of extant Lyot coronagraphs on much larger telescopes corrected with current-generation AO systems. This suggests that small apertures corrected to extreme adaptive optics (ExAO) levels can be used to carry out initial surveys for close brown dwarf and stellar companions, leaving followup observations for larger telescopes.

accepted for publication in the Astrophysical Journal

References in corpus (5)

• Theoretical Limits on Extrasolar Terrestrial Planet Detection with Coronagraphs
• The Palomar/Keck Adaptive Optics Survey of Young Solar Analogs: Evidence for a Universal Companion Mass Function
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• Extreme adaptive optics imaging with a clear and well-corrected off-axis telescope sub-aperture
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• Precise Dynamical Masses of Directly Imaged Companions from Relative Astrometry, Radial Velocities, and Hipparcos-Gaia DR2 Accelerations
• The Dynamical Mass and Three-Dimensional Orbit of HR7672B: A Benchmark Brown Dwarf with High Eccentricity
• Laboratory demonstration of a mid-infrared AGPM vector vortex coronagraph
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• The Orbital Eccentricities of Directly Imaged Companions Using Observable-Based Priors: Implications for Population-level Distributions