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Dust Production Rates in the Fomalhaut Debris Disk from SOFIA/FORCAST Mid-infrared Imaging

Adams, J. D. and Herter, T. L. and Lau, R. M. and Trinh, C. and Hankins, M. (2018) Dust Production Rates in the Fomalhaut Debris Disk from SOFIA/FORCAST Mid-infrared Imaging. Astrophysical Journal, 862 (2). Art. No. 161. ISSN 1538-4357. doi:10.3847/1538-4357/aacf96.

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We present the first spatially resolved mid-infrared (37.1 μm) image of the Fomalhaut debris disk. We use point spread function fitting and subtraction to distinctly measure the flux from the unresolved component and the debris disk. We measure an infrared excess in the point source of 0.9 ± 0.2 Jy, consistent with emission from warm dust in an inner disk structure, and inconsistent with a stellar wind origin. We cannot confirm or rule out the presence of a pileup ring near the star. In the cold region, the 37 μm imaging is sensitive to emission from small, blowout grains, which is an excellent probe of the dust production rate from planetesimal collisions. Under the assumptions that the dust grains are icy aggregates and the debris disk is in steady state, this result is consistent with the dust production rates predicted by Kenyon & Bromley from theoretical models of icy planet formation. We find a dust luminosity of (7.9 ± 0.8) × 10^(−4) L⊙ and a dust mass of 8–16 lunar masses, depending on grain porosity, with ~1 lunar mass in grains with radius 1 μm–1 mm. If the grains are icy and highly porous, meter-sized objects must be invoked to explain the far-infrared, submm, and mm emission. If the grains are composed of astronomical silicates, there is a dearth of blowout grains and the mass loss rate is well below the predicted dust production values.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Adams, J. D.0000-0001-7645-8913
Herter, T. L.0000-0002-3856-8385
Hankins, M.0000-0001-9315-8437
Additional Information:© 2018 The American Astronomical Society. Received 2018 March 14; revised 2018 June 23; accepted 2018 June 25; published 2018 August 2. We thank K. Stapelfeldt for sharing his PSF-subtracted MIPS image of Fomalhaut and K. Su for sharing her inner-disk model SEDs. We thank the SOFIA ground crew, flight crew, and Mission Operations for their successful execution of the SOFIA observations. We also thank an anonymous referee whose suggestions led to the improvement of this manuscript. This work is based on observations made with the NASA/DLR SOFIA. SOFIA science mission operations are conducted jointly by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901. Facilities: Spitzer - Spitzer Space Telescope satellite, SOFIA - , Herschel. -
Funding AgencyGrant Number
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OK 0901
Subject Keywords:circumstellar matter – infrared: planetary systems – planet–disk interactions
Issue or Number:2
Record Number:CaltechAUTHORS:20180808-160605291
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Official Citation:J. D. Adams et al 2018 ApJ 862 161
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:88677
Deposited By: Tony Diaz
Deposited On:09 Aug 2018 14:40
Last Modified:16 Nov 2021 00:28

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