A near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around eps Eridani and tau Ceti with CHARA/FLUOR
English
Di Folco, Emmanuel[Observatoire de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland > > > >]
Absil, Olivier[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Augereau, J.-C.[Laboratoire d'Astrophysique de l'Observatoire de Grenoble, UMR CNRS/UJF 5571, BP 53, 38041 Grenoble Cedex 9, France]
Mérand, A.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
Coudé Du Foresto, V.[LESIA, UMR8109, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France]
Thévenin, F.[Laboratoire Cassiopée, CNRS, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France]
Defrere, Denis[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
Kervella, P.[LESIA, UMR8109, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France]
Ten Brummelaar, T. A.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
McAlister, H. A.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
Ridgway, S. T.[National Optical Astronomical Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA ; Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
Sturmann, J.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
Sturmann, L.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
Turner, N. H.[Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3969, Atlanta, Georgia 30302-3965, USA]
[en] stars: individual: tau Cet & eps Eri ; stars: fundamental parameters ; circumstellar matter ; methods: observational ; techniques: interferometric
[en] Context: The quest for hot dust in the central region of debris disks requires high resolution and high dynamic range imaging. Near-infrared interferometry is a powerful means to directly detect faint emission from hot grains. Aims: We probed the first 3 AU around tau Ceti and eps Eridani with the CHARA array (Mt Wilson, USA) in order to gauge the 2 mum excess flux emanating from possible hot dust grains in the debris disks and to also resolve the stellar photospheres. Methods: High precision visibility amplitude measurements were performed with the FLUOR single mode fiber instrument and telescope pairs on baselines ranging from 22 to 241 m of projected length. The short baseline observations allow us to disentangle the contribution of an extended structure from the photospheric emission, while the long baselines constrain the stellar diameter. Results: We have detected a resolved emission around tau Cet, corresponding to a spatially integrated, fractional excess flux of 0.98±0.21 × 10[SUP]-2[/SUP] with respect to the photospheric flux in the K'-band. Around eps Eri, our measurements can exclude a fractional excess of greater than 0.6× 10[SUP]-2[/SUP] (3sigma). We interpret the photometric excess around tau Cet as a possible signature of hot grains in the inner debris disk and demonstrate that a faint, physical or background, companion can be safely excluded. In addition, we measured both stellar angular diameters with an unprecedented accuracy: Theta_LD(tau Cet)= 2.015 ± 0.011 mas and Theta_LD(eps Eri)=2.126 ± 0.014 mas.
[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
