TY - JOUR
T1 - Detection of Near-infrared Water Ice at the Surface of the (Pre)Transitional Disk of AB Aur
T2 - Informing Icy Grain Abundance, Composition, and Size
AU - Betti, S. K.
AU - Follette, K.
AU - Jorquera, S.
AU - Duchêne, G.
AU - Mazoyer, J.
AU - Bonnefoy, M.
AU - Chauvin, G.
AU - Pérez, L. M.
AU - Boccaletti, A.
AU - Pinte, C.
AU - Weinberger, A. J.
AU - Grady, C.
AU - Close, L. M.
AU - Defrère, D.
AU - Downey, E. C.
AU - Hinz, P. M.
AU - Ménard, F.
AU - Schneider, G.
AU - Skemer, A. J.
AU - Vaz, A.
N1 - Funding Information:
We thank the anonymous referee for their careful review. We thank Esther Buenzli, Vanessa Bailey, Timothy Rodigas, and Jared Males for contributing to or obtaining the original imagery. We thank Kellen Lawson for his helpful suggestion to look into the differential evolution algorithm as a way to fit the forward modeled disks. S.K.B. and K.B.F. acknowledge support from NSF AST-2009816. S.J. acknowledges support from the National Agency for Research and Development (ANID) Scholarship Program, Doctorado Becas Nacionales/2020-21212356. L.P. gratefully acknowledges support by the ANID BASAL project FB210003, and by ANID—Millennium Science Initiative Program—NCN19_171. We acknowledge the use of the Large Binocular Telescope Interferometer (LBTI) and the support from the LBTI team. MCFOST is funded by the Australian Research Council under contracts FT170100040 and DP180104235 and by the Agence Nationale pour la Recherche (ANR) of France under contract ANR-16-CE31-0013. This research has made use of the SVO Filter Profile Service ( http://svo2.cab.inta-csic.es/theory/fps/ ) supported by the Spanish MINECO through grant AYA2017-84089. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/4/1
Y1 - 2022/4/1
N2 - We present near-infrared Large Binocular Telescope LMIRCam imagery of the disk around the Herbig Ae/Be star AB Aurigae. A comparison of the 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 point-spread function subtraction, we detect the disk at high signal-to-noise ratios in all three bands. We find strong morphological differences between the bands, including asymmetries consistent with the observed spiral arms within 100 au in L′ . An apparent deficit of scattered light at 3.08 μm relative to the 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 that 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 colocated, and that the optical depth effects in each wavelength result from probing the grain population at different disk surface depths. The morphological similarity between Ks and H2O suggests that 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.
AB - We present near-infrared Large Binocular Telescope LMIRCam imagery of the disk around the Herbig Ae/Be star AB Aurigae. A comparison of the 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 point-spread function subtraction, we detect the disk at high signal-to-noise ratios in all three bands. We find strong morphological differences between the bands, including asymmetries consistent with the observed spiral arms within 100 au in L′ . An apparent deficit of scattered light at 3.08 μm relative to the 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 that 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 colocated, and that the optical depth effects in each wavelength result from probing the grain population at different disk surface depths. The morphological similarity between Ks and H2O suggests that 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.
KW - Circumstellar matter
KW - Pre-main sequence stars
KW - Protoplanetary disks
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U2 - 10.3847/1538-3881/ac4d9b
DO - 10.3847/1538-3881/ac4d9b
M3 - Article
AN - SCOPUS:85126289247
SN - 0004-6256
VL - 163
JO - Astronomical Journal
JF - Astronomical Journal
IS - 4
M1 - 145
ER -