2006/04/14 by Beth A. Biller, Beth Biller, Laird M. Close +10 · 15 citations
Physics and Astronomy · #Adaptive optics #Artificial intelligence #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Calibration #Computer science #Full width at half maximum #Gaussian #Optics #Physics #Resolution (logic) #Stars #Stellar, planetary, and galactic studies #Strehl ratio #astro-ph
paper · pdf · doi:10.1086/505194
published in The Astrophysical Journal 647(1), 464-470 (IOP Publishing) · 18 pages, 7 figures, accepted by the Astrophysical Journal
arxiv created 2006/04/14 · openalex publication_date 2006/08/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We imaged the symbiotic star CH Cyg and two PSF calibration stars using the unique 6.5 m MMT deformable secondary adaptive optics system. Our high-resolution (FWHM = 0 3), very high Strehl (98% ± 2%), mid-infrared (9.8 and 11.7 μm) images of CH Cyg allow us to probe finer length scales than ever before for this object. CH Cyg is significantly extended compared to our unresolved PSF calibration stars (μ UMa and α Her) at 9.8 and 11.7 μm. We estimated the size of the extension by convolving a number of simple Gaussian models with the μ UMa PSF and determining which model provided the best fit to the data. Adopting the Hipparcos distance for this object of 270 pc, we found a nearly Gaussian extension with a FWHM at 9.8 μm of ~40.5 ± 2.7 AU (0 15 ± 0 01) and a FWHM at 11.7 μm of 45.9 ± 2.7 AU (0 17 ± 0 01). After subtracting out the Gaussian component of the emission (convolved with our PSF), we found a faint ~ 0 7 asymmetric extension, which peaks in flux ~0 5 north of the stars. This extension is roughly coincident with the northern knotlike feature seen in HST WFPC2 images obtained in 1999.