Defrère, D. and Absil, O. and Augereau, J.-C. and Di Folco, E. and Berger, J.-P. and Coudé du Foresto, F. and Kervella, P. and Le Bouquin, J.-B. and Lebreton, J. and Millan-Gabet, R. and Monnier, J. D. and Olofsson, J. and Traub, W. (2011) Hot exozodiacal dust resolved around Vega with IOTA/IONIC. Astronomy and Astrophysics, 534 . Art. No. A5. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20111128-113716005
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Context. Although debris discs have been detected around a significant number of main-sequence stars, only a few of them are known to harbour hot dust in their inner part where terrestrial planets may have formed. Thanks to infrared interferometric observations, it is possible to obtain a direct measurement of these regions, which are of prime importance for preparing future exo-Earth characterisation missions. Aims. We resolve the exozodiacal dust disc around Vega with the help of infrared stellar interferometry and estimate the integrated H-band flux originating from the first few AUs of the debris disc. Methods. Precise H-band interferometric measurements were obtained on Vega with the 3-telescope IOTA/IONIC interferometer (Mount Hopkins, Arizona). Thorough modelling of both interferometric data (squared visibility and closure phase) and spectral energy distribution was performed to constrain the nature of the near-infrared excess emission. Results. Resolved circumstellar emission within ~6 AU from Vega is identified at the 3-σ level. The most straightforward scenario consists in a compact dust disc producing a thermal emission that is largely dominated by small grains located between 0.1 and 0.3 AU from Vega and accounting for 1.23 ± 0.45% of the near-infrared stellar flux for our best-fit model. This flux ratio is shown to vary slightly with the geometry of the model used to fit our interferometric data (variations within ± 0.19%). Conclusions. The presence of hot exozodiacal dust in the vicinity of Vega, initially revealed by K-band CHARA/FLUOR observations, is confirmed by our H-band IOTA/IONIC measurements. Whereas the origin of the dust is still uncertain, its presence and the possible connection with the outer disc suggest that the Vega system is currently undergoing major dynamical perturbations.
|Additional Information:||© 2011 ESO. Received 4 April 2011. Accepted 2 August 2011. Published online 20 September 2011. The authors acknowledge Sylvestre Lacour (LESIA) and Ettore Pedretti (St. Andrews) for sharing dispersed calibrator data of 2006. The authors are also grateful to Arnaud Magette, Charles Hanot, Pierre Riaud, and Jean Surdej (IAGL), Bertrand Mennesson (NASA/JPL), Jason Aufdenberg (ERAU), Gerd Weigelt (MPIFR), and Paul Lepoulpe for helpful advice. This research was supported by the International Space Science Institute (ISSI) in Bern, Switzerland (“Exozodiacal Dust discs and Darwin” working group, http://www.issibern.ch/teams/exodust/). D.D. acknowledges the support of the Belgian National Science Foundation (“FRIA”), of EII (Fizeau programme), and the MPIFR. O.A. acknowledges the support from an F.R.S.- FNRS Postdoctoral Fellowship. D.D. and O.A. acknowledge support from the Communauté française de Belgique – Actions de recherche concertées – Académie universitaire Wallonie-Europe. D.D., O.A., and J.C.A. thank the French National Research Agency (ANR) for financial support through contract ANR-2010 BLAN-0505-01 (EXOZODI). This research received the support of PHASE, the high angular resolution partnership between ONERA, Observatoire de Paris, CNRS, and University Denis Diderot Paris 7.|
|Subject Keywords:||instrumentation: high angular resolution; techniques: interferometric; circumstellar matter|
|Official Citation:||Hot exozodiacal dust resolved around Vega with IOTA/IONIC A5 D. Defrère et al. Published online: 20 September 2011 DOI: http://dx.doi.org/10.1051/0004-6361/201117017|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||28 Nov 2011 21:11|
|Last Modified:||26 Dec 2012 14:27|
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