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Constraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared Surveys

Mennesson, B. and Millan-Gabet, R. and Serabyn, E. and Colavita, M. M. and Absil, O. and Bryden, G. and Wyatt, M. and Danchi, W. and Defrère, D. and Doré, O. and Hinz, P. and Kuchner, M. and Ragland, S. and Scott, N. and Stapelfeldt, K. and Traub, W. and Woillez, J. (2014) Constraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared Surveys. Astrophysical Journal, 797 (2). Art. No. 119. ISSN 0004-637X.

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Forty-seven nearby main-sequence stars were surveyed with the Keck Interferometer mid-infrared Nulling instrument (KIN) between 2008 and 2011, searching for faint resolved emission from exozodiacal dust. Observations of a subset of the sample have already been reported, focusing essentially on stars with no previously known dust. Here we extend this previous analysis to the whole KIN sample, including 22 more stars with known near-and/or far-infrared excesses. In addition to an analysis similar to that of the first paper of this series, which was restricted to the 8-9 µm spectral region, we present measurements obtained in all 10 spectral channels covering the 8-13 µm instrumental bandwidth. Based on the 8-9 µm data alone, which provide the highest signal-to-noise measurements, only one star shows a large excess imputable to dust emission (η Crv), while four more show a significant (> 3σ) excess: β Leo, β UMa, ζ Lep, and y Oph. Overall, excesses detected by KIN are more frequent around A-type stars than later spectral types. Astatistical analysis of the measurements further indicates that stars with known far-infrared (y ≥ 70 µm) excesses have higher exozodiacal emission levels than stars with no previous indication of a cold outer disk. This statistical trend is observed regardless of spectral type and points to a dynamical connection between the inner (zodi-like) and outer (Kuiper-Belt-like) dust populations. The measured levels for such stars are clustering close to the KIN detection limit of a few hundred zodis and are indeed consistent with those expected from a population of dust that migrated in from the outer belt by Poynting-Robertson drag. Conversely, no significant mid-ilinfrared excess is found around sources with previously reported near-infrared resolved excesses, which typically have levels of the order of 1% over the photospheric flux. If dust emission is really at play in these near-infrared detections, the absence of a strong mid-infrared counterpart points to populations of very hot and small (submicron) grains piling up very close to the sublimation radius. For solar-type stars with no known infrared excess, likely to be the most relevant targets for a future exo-Earth direct imaging mission, we find that their median zodi level is 12±24 zodis and lower than 60 (90) zodis with 95% (99%) confidence, if a lognormal zodi luminosity distribution is assumed.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mennesson, B.0000-0003-4205-4800
Millan-Gabet, R.0000-0003-0447-5866
Absil, O.0000-0002-4006-6237
Defrère, D.0000-0003-3499-2506
Doré, O.0000-0002-5009-7563
Hinz, P.0000-0002-1954-4564
Kuchner, M.0000-0002-2387-5489
Stapelfeldt, K.0000-0002-2805-7338
Additional Information:© 2014 American Astronomical Society. Received 2014 July 5; accepted 2014 October 1; published 2014 December 8. The Keck Interferometer was funded by the National Aeronautics and Space Administration (NASA). Part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, and at the NASA Exoplanet Science Center (NExScI), under contract with NASA. The Keck Observatory was made possible through the generous financial support of the W. M. Keck Foundation. This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory. M.C.W. is grateful for support from the European Union through ERC grant number 279973.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
European Research Council (ERC)279973
Subject Keywords:circumstellar matter; infrared: stars; instrumentation: interferometers
Issue or Number:2
Record Number:CaltechAUTHORS:20150115-125753252
Persistent URL:
Official Citation:Constraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared Surveys B. Mennesson et al. 2014 ApJ 797 119
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53789
Deposited By: Ruth Sustaita
Deposited On:15 Jan 2015 22:56
Last Modified:07 Apr 2020 19:08

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