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Dust in the inner regions of debris disks around a stars

Akeson, R. L. and Ciardi, D. R. and Millan-Gabet, R. and Merand, A. and Di Folco, E. and Monnier, J. D. and Beichman, C. A. and Absil, O. and Aufdenberg, J. and McAlister, H. and ten Brummelaar, T. and Sturmann, J. and Sturmann, L. and Turner, N. (2009) Dust in the inner regions of debris disks around a stars. Astrophysical Journal, 691 (2). pp. 1896-1908. ISSN 0004-637X.

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We present infrared interferometric observations of the inner regions of two A-star debris disks, β Leo and ζ Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and long (> 200 m) baselines. For the target stars, the short-baseline visibilities are lower than expected for the stellar photosphere alone, while those of a check star, δ Leo, are not. We interpret this visibility offset of a few percent as a near-infrared (NIR) excess arising from dust grains which, due to the instrumental field of view, must be located within several AU of the central star. For β Leo, the NIR excess-producing grains are spatially distinct from the dust which produces the previously known mid-infrared (MIR) excess. For ζ Lep, the NIR excess may be spatially associated with the MIR excess-producing material. We present simple geometric models which are consistent with the NIR and MIR excesses and show that for both objects, the NIR-producing material is most consistent with a thin ring of dust near the sublimation radius, with typical grain sizes smaller than the nominal radiation pressure blowout radius. Finally, we discuss possible origins of the NIR-emitting dust in the context of debris disk evolution models.

Item Type:Article
Related URLs:
URLURL TypeDescription
Akeson, R. L.0000-0001-9674-1564
Ciardi, D. R.0000-0002-5741-3047
Millan-Gabet, R.0000-0003-0447-5866
Monnier, J. D.0000-0002-3380-3307
Beichman, C. A.0000-0002-5627-5471
Absil, O.0000-0002-4006-6237
ten Brummelaar, T.0000-0002-0114-7915
Additional Information:© 2009 American Astronomical Society. Received 2008 June 13; accepted 2008 October 15; published 2009 February 12. We thank the CHARA staff, particularly P. J. Goldfinger, for their excellent help in obtaining the data and the FLUOR team for support of the instrument. We thank Christine Chen for kindly providing IRS spectra, Karl Stapelfeldt for the MIPS measurement, and Mark Wyatt, Scott Kenyon, and Hal Levison for helpful discussions. The anonymous referee made several helpful suggestions to improve the paper. This work was performed at the Michelson Science Center, Caltech and made use of the SIMBAD database, operated at CDS, Strasbourg, France, and the NASA Star and Exoplanet Database (NStED) at the Infrared Processing and Analysis Center. NStED is jointly funded by the National Aeronautics and Space Administration (NASA) via Research Opportunities in Space Sciences grant 2003 TPF-FS, and by NASA’s Michelson Science Center. Facilities: CHARA, GEMINI.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:circumstellar matter – stars: individual (β; Leo, ζ Lep) infrared interferometric survey; main-sequence stars; vega-like systems; solar-type stars; sun-like stars; chara array; planet formation; asteroid belt; beam combiner; zeta-leporis
Issue or Number:2
Record Number:CaltechAUTHORS:20090416-095541461
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13995
Deposited By: Marie Noren
Deposited On:21 Apr 2009 18:50
Last Modified:24 Feb 2020 10:30

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