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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 693750.0, MPI für Astronomie / Publikationen_mpia
Kinks and dents in protoplanetary disks: Rapid infrared variability as evidence for large structural perturbations
Authors:Flaherty, K. M.; Muzerolle, J.; Rieke, G.; Gutermuth, R.; Balog, Z.; Herbst, W.; Megeath, S. T.
Date of Publication (YYYY-MM-DD):2013
Title of Journal:The Astronomical Journal
Volume:145
Issue / Number:3
Start Page:id. 66 (23 pp)
Audience:Not Specified
Abstract / Description:We report on synoptic observations at 3.6 and 4.5 μm of young stellar objects in IC 348 with 38 epochs covering 40 days. We find that among the detected cluster members, 338 at [3.6] and 269 at both [3.6] and [4.5], many are variable on daily to weekly timescales with typical fluctuations of ~0.1 mag. The fraction of variables ranges from 20% for the diskless pre-main sequence stars to 60% for the stars still surrounded by infalling envelopes. We also find that stars in the exposed cluster core are less variable than the stars in the dense, slightly younger, southwestern ridge. This trend persists even after accounting for the underlying correlation with infrared spectral energy distribution type, suggesting that the change in variable fraction is not simply a reflection of the change in relative fraction of class I versus class II sources across the cloud, but instead reflects a change in variability with age. We also see a strong correlation between infrared variability and X-ray luminosity among the class II sources. The observed variability most likely reflects large changes in the structure of the inner wall located at the dust sublimation radius. We explore the possibility that these structural perturbations could be caused by a hot spot on the star heating dust above the sublimation temperature, causing it to evaporate rapidly, and increasing the inner radius for a portion of the disk. Under a number of simplifying assumptions we show that this model can reproduce the size and timescale of the 3.6 and 4.5 μm fluctuations. Regardless of its source, the infrared variability indicates that the inner disk is not a slowly evolving entity, but instead is a bubbling, warped, dented mass of gas and dust whose global size and shape fluctuate in a matter of days.
Free Keywords:accretion; accretion disks; stars: formation; stars: pre-main sequence; stars: protostars; stars: variables: T Tauri; Herbig Ae/Be
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6256 %R 10.1088/0004-6256/145/3/66
URL:http://cdsads.u-strasbg.fr/abs/2013AJ....145...66F
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