Mid-infrared imaging of the post-asymptotic giant branch star AC Herculis with the Multiple Mirror Telescope adaptive optics system

Laird M. Close, Beth Biller, William F. Hoffmann, Phil M. Hinz, John H. Bieging, Francois Wildi, Michael Lloyd-Hart, Guido Brusa, Don Fisher, Doug Miller, Roger Angel

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

We utilized the unique 6.5 m Multiplie Mirror Telescope deformable secondary adaptive optics (AO) system to produce high-resolution (FWHM = 0″.3), very high Strehl mid-infrared (9.8, 11.7, and 18 μm) images of the post-asymptotic giant branch star AC Her. The very high (98% ± 2%) Strehls achieved with mid-IR AO led naturally to an ultrastable point-spread function (PSF) independent of air mass, seeing, or location on the sky. We find no significant difference between AC Her's morphology and our unresolved PSF calibration stars (μ UMa and α Her) at 9.8, 11.7, and 18 μm. Our current observations do not confirm any extended mid-IR structure around AC Her. These observations are in conflict with previously reported Keck (seeing-limited) 11.7 and 18 μm images that suggested the presence of a resolved ∼0″.6 edge-on circumbinary disk. We conclude that AC Her has no extended mid-IR structure on scales greater than 0″.2 (R < 75 AU). These first results of mid-IR AO science are very encouraging for future high-accuracy mid-IR imaging with this technique.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume598
Issue number1 II
DOIs
Publication statusPublished - Nov 20 2003

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Keywords

  • Binaries: general
  • Instrumentation: adaptive optics
  • Stars: AGB and post-AGB
  • Stars: evolution
  • Stars: formation

ASJC Scopus subject areas

  • Space and Planetary Science

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