Few skewed disks found in first closure-phase survey of Herbig Ae/Be stars

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

Abstract

Using the three-telescope IOTA interferometer on Mount Hopkins, we report results from the first near-infrared (lambda = 1.65 mu m) closure-phase survey of young stellar objects (YSOs). These closure phases allow us to unambiguously detect departures from centrosymmetry (i.e., skew) in the emission pattern from YSO disks on the scale of similar to 4 mas, expected from generic "flared disk'' models. Six of 14 targets showed small, yet statistically significant nonzero closure phases, with largest values from the young binary system MWC 361-A and the (pre-main-sequence?) Be star HD 45677. Our observations are quite sensitive to the vertical structure of the inner disk, and we confront the predictions of the "puffed-up inner wall'' models of Dullemond, Dominik, & Natta (DDN). Our data support disk models with curved inner rims because the expected emission appears symmetrically distributed around the star over a wide range of inclination angles. In contrast, our results are incompatible with the models possessing vertical inner walls because they predict extreme skewness (i.e., large closure phases) from the near-IR disk emission that is not seen in our data. In addition, we also present the discovery of mysterious H-band "halos'' (similar to 5%-10% of light on scales 0."01-0."50) around a few objects, a preliminary "parametric imaging'' study for HD 45677, and the first astrometric orbit for the young binary MWC 361-A.

Additional Information

© 2006 The American Astronomical Society. Received 2006 February 2; accepted 2006 April 17. J.D.M. thanks D. Pourbaix for reanalyzing the Hipparcos parallax of MWC 361-A using the new orbital parameters and A. Tannirkulam for photometry from the MDM Observatory. The authors gratefully acknowledge support from the Smithsonian Astrophysical Observatory, NASA (for third telescope development and NASA NNG05G1180G), the National Science Foundation (AST 01-38303, AST 03-52723), and the Jet Propulsion Laboratory (JPL awards 1236050 and 1248252). E.P. was partially supported by a SAO Predoctoral fellowship, J.D.M. by a Harvard-Smithsonian CfA fellowship, and R.M.-G. and J.-P.B. were partially supported through NASA Michelson Postdoctoral Fellowships. The IONIC3 instrument has been developed by LAOG and LETI in the context of the IONIC collaboration (LAOG, IMEP, LETI). The IONIC project is funded by the CNRS (France) and CNES (France). This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France, and NASA's Astrophysics Data System Abstract Service. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This work has made use of services produced by the Michelson Science Center at the California Institute of Technology.

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