Astrophysics, abstract
astro-ph/0606059

From: Rafael Millan-Gabet [view email]

Date: Fri, 2 Jun 2006 15:58:13 GMT (30kb)

Bright Localized Near-Infrared Emission at 1-4 AU in the AB Aurigae Disk Revealed by IOTA Closure Phases

Authors: R. Millan-Gabet, J. D. Monnier, J.-P. Berger, W.A. Traub, F.P. Schloerb, E. Pedretti, M. Benisty, N.P. Carleton, P. Haguenauer, P. Kern, P. Labeye, M. G. Lacasse, F. Malbet, K. Perraut, M. Pearlman, N.Thureau

Comments: Accepted by Astrophysical Journal Letters

We report on the detection of localized off-center emission at 1-4 AU in the circumstellar environment of the young stellar object AB Aurigae. We used closure phase measurements in the near-infrared made at the long baseline interferometer IOTA, the first obtained on a young stellar object using this technique. When probing sub-AU scales, all closure phases are close to zero degrees, as expected given the previously-determined size of the AB Aurigae inner dust disk. However, a clear closure phase signal of -3.5 +/- 0.5 degrees is detected on one triangle containing relatively short baselines, requiring a high degree of non-point symmetry from emission at larger (AU-sized) scales in the disk. We have not identified any alternative explanation for these closure phase results and demonstrate that a ``disk hot spot'' model can fit our data. We speculate that such asymmetric near-infrared emission detected might arise as a result of localized viscous heating due to a gravitational instability in the AB Aurigae disk, or to the presence of a close stellar companion or accreting sub-stellar object.

http://arxiv.org/abs/astro-ph/0606059