High-Resolution Mid-Infrared Imaging of the Asymptotic Giant Branch Star RV Bootis with the Steward Observatory Adaptive Optics System

We present high-resolution (~0.″1), very high Strehl ratio (0.97 ± 0.03) mid-IR adaptive optics (AO) images of the asymptotic giant branch (AGB) star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 μm in 2003 May and 8.8, 9.8, and 11.7 μm in 2004 February) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 μm, the extension is somewhat more pronounced at 9.8 μm. With such high Strehl ratios, we can achieve superresolutions of 0.″1 by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0.″16 FWHM extension at a position angle of 120°. At a distance of 390 pc, this corresponds to a FWHM of 60 AU. We measure a total flux at 9.8 μm of 145 ± 24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 μm AO image, we derive a disk dust mass of 1.6 × 10-6 M☉ and an inclination of 30°-45° from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebulae.