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Published September 20, 2013 | Published
Journal Article Open

An Azimuthal Asymmetry in the LkHα 330 Disk


Theory predicts that giant planets and low mass stellar companions shape circumstellar disks by opening annular gaps in the gas and dust spatial distribution. For more than a decade it has been debated whether this is the dominant process that leads to the formation of transitional disks. In this paper, we present millimeter-wave interferometric observations of the transitional disk around the young intermediate mass star LkHα 330. These observations reveal a lopsided ring in the 1.3 mm dust thermal emission characterized by a radius of about 100 AU and an azimuthal intensity variation of a factor of two. By comparing the observations with a Gaussian parametric model, we find that the observed asymmetry is consistent with a circular arc, that extends azimuthally by about 90° and emits about 1/3 of the total continuum flux at 1.3 mm. Hydrodynamic simulations show that this structure is similar to the azimuthal asymmetries in the disk surface density that might be produced by the dynamical interaction with unseen low mass companions orbiting within 70 AU from the central star. We argue that such asymmetries might lead to azimuthal variations in the millimeter-wave dust opacity and in the dust temperature, which will also affect the millimeter-wave continuum emission. Alternative explanations for the observed asymmetry that do not require the presence of companions cannot be ruled out with the existing data. Further observations of both the dust and molecular gas emission are required to derive firm conclusions on the origin of the asymmetry observed in the LkHα 330 disk.

Additional Information

© 2013 American Astronomical Society. Received 2013 April 18; accepted 2013 July 12; published 2013 August 30. We thank the OVRO/CARMA staff and the CARMA observers for their assistance in obtaining the data. Support for CARMA construction was derived from the Gordon and Betty Moore Foundation; the Kenneth T. and Eileen L. Norris Foundation; the James S. McDonnell Foundation; the Associates of the California Institute of Technology; the University of Chicago; the States of California, Illinois, and Maryland; and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement, and by the CARMA partner universities. We acknowledge support from the Owens Valley Radio Observatory, which is supported by the National Science Foundation through grant AST-1140063. A.I. and J.M.C. acknowledge support from NSF award AST-1109334. We thank Adam Kraus for sharing unpublished results.

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