YSOVAR: Mid-infrared Variability among YSOs in the Star Formation Region Serpens South

Creators: Wolk, Scott J.; Günther, H. Moritz; Poppenhaeger, Katja; Winston, E.; Rebull, L. M.; Stauffer, J. R.; Gutermuth, R. A.; Cody, A. M.; Hillenbrand, L. A.; Plavchan, P.; Covey, K. R.; Song, Inseok

Abstract

We present a time-variability study of young stellar objects (YSOs) in the Serpens South cluster performed at 3.6 and 4.5 μm with the Spitzer Space Telescope; this study is part of the Young Stellar Object VARiability project. We have collected light curves for more than 1500 sources, including 85 cluster members, over 38 days. This includes 44 class I sources, 19 sources with flat spectral energy distributions (SEDs), 17 class II sources, and five diskless YSO candidates. We find a high variability fraction among embedded cluster members of ~70%, whereas young stars without a detectable disk display no variability. We detect periodic variability for 32 sources with periods primarily in the range of 0.2–14 days and a subset of fast rotators thought to be field binaries. The timescale for brightness changes are shortest for stars with the most photospheric SEDs and longest for those with flat or rising SEDs. While most variable YSOs become redder when fainter, as would be expected from variable extinction, about 10% get bluer as they get fainter. One source, SSTYSV J183006.13−020108.0, exhibits "cyclical" color changes.

Additional Information

© 2018 American Astronomical Society. Received 2017 August 2. Accepted 2017 December 15. Published 2018 February 1 . 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. 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 research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013). This research has made use of the SIMBAD database and the VizieR catalog access tool (Ochsenbein et al. 2000), both operated at CDS, Strasbourg, France, and 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. H.M.G. acknowledges Spitzer grant 1490851. K.P. was funded through the Sagan Fellowship program executed by the NASA Exoplanet Science Institute. H.Y.A.M. and P.P. acknowledge support by the IPAC Visiting Graduate Fellowship program at Caltech/IPAC. P.P. also acknowledges the JPL Research and Technology Development and Exoplanet Exploration programs. R.A.G. gratefully acknowledges funding support from NASA ADAP grants NNX11AD14G and NNX13AF08G and Caltech/JPL awards 1373081, 1424329, and 1440160 in support of Spitzer Space Telescope observing programs. S.J.W. was supported by NASA contract NAS8-03060 (Chandra X-ray Center). Facilities: Spitzer - Spitzer Space Telescope satellite, Chandra.

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