The Fomalhaut debris disk seen from every angle with interferometry

Creators: Absil, O.; Mennesson, B.; Le Bouquin, J.-B.; Augereau, J.-C.; Millan-Gabet, R.; Colavita, M.; Hinz, P.; Liu, W.; Serabyn, G.

Others:: Danchi, William C.; Delplancke, Françoise; Rajagopal, Jayadev K.

Abstract

In this paper, we present the results of three different studies of the Fomalhaut debris disk with infrared interferometry. First, VLTI/AMBER measurements are used to determine the position angle of the slightly oblate rapidly rotating photosphere by means of differential phase measurements across the Br-gamma photospheric line. This measurement allows us to confirm that the debris disk is located in the equatorial plane of its host star. Second, we use VLTI/VINCI to search for resolved near-infrared emission around the stellar photosphere, which would correspond to the presence of large amounts of hot dust grains located between the sublimation radius and the habitable zone. Our observations reveal a small excess of 0.88%±0.12% in K band relative to the photospheric flux. Finally, we use the Keck Interferometer Nuller in order to derive additional constraints on the nature of the resolved infrared emission. Our observations suggest a marginal detection of a circumstellar excess at 10 μm, which we use together with the VINCI detection to model the circumstellar emission. Preliminary results from this modeling effort are discussed.

Additional Information

© 2010 Society of Photo-Optical Instrumentation Engineers (SPIE). O. A. acknowledges the financial support of F.R.S.-FNRS (Postdoctoral Researcher), and support from "Communauté Française de Belgique – Actions de Recherche Concertées – Académie universitaire Wallonie-Europe". This research was partly funded by the International Space Science Institute ("Exozodiacal Dust Disks and Darwin" working group). Part of this work is based on observations collected at the VLTI (ESO Paranal, Chile), under program ID 082.C-0376 (AMBER Guaranteed Time of the Osservatorio Astrofisico di Arcetri, INAF, Italy) and using public VINCI commissioning data. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

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