ISM Dust Grains and N-band Spectral Variability in the Spatially Resolved Subarcsecond Binary UY Aur

Abstract

The 10 micron silicate feature is an essential diagnostic of dust-grain growth and planet formation in young circumstellar disks. The Spitzer Space Telescope has revolutionized the study of this feature, but due to its small (85cm) aperture, it cannot spatially resolve small/medium separation binaries (<3"; <420 AU) at the distances of the nearest star-forming regions (~140 pc). Large, 6-10m ground-based telescopes with mid-infrared instruments can resolve these systems. In this paper, we spatially resolve the 0.88" binary, UY Aur, with MMTAO/BLINC-MIRAC4 mid-infrared spectroscopy. We then compare our spectra to Spitzer/IRS (unresolved) spectroscopy, and resolved images from IRTF/MIRAC2, Keck/OSCIR and Gemini/Michelle, which were taken over the past decade. We find that UY Aur A has extremely pristine, ISM-like grains and that UY Aur B has an unusually shaped silicate feature, which is probably the result of blended emission and absorption from foreground extinction in its disk. We also find evidence for variability in both UY Aur A and UY Aur B by comparing synthetic photometry from our spectra with resolved imaging from previous epochs. The photometric variability of UY Aur A could be an indication that the silicate emission itself is variable, as was recently found in EX Lupi. Otherwise, the thermal continuum is variable, and either the ISM-like dust has never evolved, or it is being replenished, perhaps by UY Aur's circumbinary disk.

arXiv comment34 pages, 12 figures, accepted to ApJ

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Cited by in corpus (11)

• The Mass Dependence Between Protoplanetary Disks and their Stellar Hosts
• Organic Molecules and Water in the Inner Disks of T Tauri Stars
• Modeling Mid-Infrared Variability of Circumstellar Disks with Non-Axisymmetric Structure
• Kinks and Dents in Protoplanetary Disks: Rapid Infrared Variability as Evidence for Large Structural Perturbations
• Circumbinary Ring, Circumstellar disks and accretion in the binary system UY Aurigae
• The Highly Dynamic Behavior of the Innermost Dust and Gas in the Transition Disk Variable LRLL 31
• Potential Drivers of Mid-Infrared Variability in Young Stars: testing physical models with multi-epoch near-infrared spectra of YSOs in ρ Oph
• Dust Grain Evolution in Spatially Resolved T Tauri Binaries
• [Fe II] emissions associated with the young interacting binary UY Aurige
• Four Decades of IRC +10216: Evolution of a Carbon Rich Dust Shell Resolved at 10 microns with MMT Adaptive Optics and MIRAC4
• Variable Accretion Processes in the Young Binary-Star System UY Aur