2022/01/21 by Sarah Betti, S. K. Betti, Katherine B. Follette +30
Chemistry · Physics and Astronomy · #Analytical Chemistry (journal) #Artificial intelligence #Astrophysics #Astrophysics and Star Formation Studies #Chemistry #Computer science #Molecular Spectroscopy and Structure #Physics #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.3847/1538-3881/ac4d9b
Accepted for publication in AJ
arxiv created 2022/01/21 · openalex publication_date 2022/03/02 · arxiv updated 2022/03/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We present near-infrared Large Binocular Telescope Interferometer LMIRCam imagery of the disk around the Herbig Ae/Be star AB Aurigae. A comparison of surface brightness at Ks (2.16 μm), H2O narrowband (3.08 μm), and L' (3.7 μm) allows us to probe the presence of icy grains in this (pre)transitional disk environment. By applying Reference Differential Imaging PSF subtraction, we detect the disk at high signal to noise in all three bands. We find strong morphological differences between bands, including asymmetries consistent with observed spiral arms within 100 AU in L'. An apparent deficit of scattered light at 3.08 μm relative to bracketing wavelengths (Ks and L') is evocative of ice absorption at the disk surface layer. However, the Δ(Ks-H2O) color is consistent with grains with little to no ice (0-5% by mass). The Δ(H2O-L') color, conversely, suggests grains with a much higher ice mass fraction (~0.68), and the two colors cannot be reconciled under a single grain population model. Additionally, we find the extremely red Δ(Ks-L') disk color cannot be reproduced under conventional scattered light modeling with any combination of grain parameters or reasonable local extinction values. We hypothesize that the scattering surfaces at the three wavelengths are not co-located, and optical depth effects result in each wavelength probing the grain population at different disk surface depths. The morphological similarity between Ks and H2O suggests their scattering surfaces are near one another, lending credence to the Δ(Ks-H2O) disk color constraint of < 5% ice mass fraction for the outermost scattering disk layer.