Near-IR imaging of T Cha: evidence for scattered-light disk structures at solar system scales

Abstract

T Chamaeleontis is a young star surrounded by a transitional disk, and a plausible candidate for ongoing planet formation. Recently, a substellar companion candidate was reported within the disk gap of this star. However, its existence remains controversial, with the counter-hypothesis that light from a high inclination disk may also be consistent with the observed data. The aim of this work is to investigate the origin of the observed closure phase signal to determine if it is best explained by a compact companion. We observed T Cha in the L and K s filters with sparse aperture masking, with 7 datasets covering a period of 3 years. A consistent closure phase signal is recovered in all L and K s datasets. Data were fit with a companion model and an inclined circumstellar disk model based on known disk parameters: both were shown to provide an adequate fit. However, the absence of expected relative motion for an orbiting body over the 3-year time baseline spanned by the observations rules out the companion model. Applying image reconstruction techniques to each dataset reveals a stationary structure consistent with forward scattering from the near edge of an inclined disk.

6 pages, 3 figures, accepted for publication in MNRAS Letters

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• The Disk Around CoKu Tau/4: Circumbinary, not Transitional
• Young Nearby Loose Associations
• Monte-Carlo Imaging for Optical Interferometry
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• New Spatially Resolved Imaging of the SR 21 Transition Disk and Constraints on the Small-Grain Disk Geometry
• Imaging protoplanets: observing transition disks with non-redundant masking
• Search for substellar-mass companions and asymmetries in their parent discs
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• Performance of the Gemini Planet Imager Non-Redundant Mask and spectroscopy of two close-separation binaries HR 2690 and HD 142527