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Spitzer Observations of Long-term Infrared Variability among Young Stellar Objects in Chamaeleon I

Flaherty, Kevin M. and DeMarchi, Lindsay and Muzerolle, James and Balog, Zoltan and Herbst, William and Megeath, S. Thomas and Furlan, Elise and Gutermuth, Robert (2016) Spitzer Observations of Long-term Infrared Variability among Young Stellar Objects in Chamaeleon I. Astrophysical Journal, 833 (1). Art. No. 104. ISSN 0004-637X.

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Infrared variability is common among young stellar objects, with surveys finding daily to weekly fluctuations of a few tenths of a magnitude. Space-based observations can produce highly sampled infrared light curves, but are often limited to total baselines of about 1 month due to the orientation of the spacecraft. Here we present observations of the Chameleon I cluster, whose low declination makes it observable by the Spitzer Space Telescope over a 200-day period. We observe 30 young stellar objects with a daily cadence to better sample variability on timescales of months. We find that such variability is common, occurring in ~80% of the detected cluster members. The change in [3.6]–[4.5] color over 200 days for many of the sources falls between that expected for extinction and fluctuations in disk emission. With our high cadence and long baseline we can derive power spectral density curves covering two orders of magnitude in frequency and find significant power at low frequencies, up to the boundaries of our 200-day survey. Such long timescales are difficult to explain with variations driven by the interaction between the disk and stellar magnetic field, which has a dynamical timescale of days to weeks. The most likely explanation is either structural or temperature fluctuations spread throughout the inner ~0.5 au of the disk, suggesting that the intrinsic dust structure is highly dynamic.

Item Type:Article
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URLURL TypeDescription Paper
Muzerolle, James0000-0002-5943-1222
Megeath, S. Thomas0000-0001-7629-3573
Furlan, Elise0000-0001-9800-6248
Gutermuth, Robert0000-0002-6447-899X
Additional Information:© 2016 The American Astronomical Society. Received 2016 June 29; revised 2016 September 27; accepted 2016 September 27; published 2016 December 9. We thank the referee for the detailed report that greatly improved the manuscript. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. The research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013). And thanks to Mary Drennan; I have not found any new stars, but there might be some new planets in here.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:accretion, accretion disks – protoplanetary disks – stars: pre-main sequence
Issue or Number:1
Record Number:CaltechAUTHORS:20161214-102055010
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Official Citation:Kevin M. Flaherty et al 2016 ApJ 833 104
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72808
Deposited By: Tony Diaz
Deposited On:14 Dec 2016 18:27
Last Modified:07 Nov 2019 21:01

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