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Periodic and Aperiodic Variability in the Molecular Cloud ρ Ophiuchus

Parks, J. Robert and Plavchan, Peter and White, Russel J. and Gee, Alan H. (2014) Periodic and Aperiodic Variability in the Molecular Cloud ρ Ophiuchus. Astrophysical Journal Supplement Series, 211 (1). Art. No. 3. ISSN 0067-0049.

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Presented are the results of a near-IR photometric survey of 1678 stars in the direction of the ρ Ophiuchus (ρ Oph) star forming region using data from the 2MASS Calibration Database. For each target in this sample, up to 1584 individual J-, H-, and K_s-band photometric measurements with a cadence of ~1 day are obtained over three observing seasons spanning ~2.5 yr; it is the most intensive survey of stars in this region to date. This survey identifies 101 variable stars with ΔK_s-band amplitudes from 0.044 to 2.31 mag and Δ(J − K_s) color amplitudes ranging from 0.053 to 1.47 mag. Of the 72 young ρ Oph star cluster members included in this survey, 79% are variable; in addition, 22 variable stars are identified as candidate members. Based on the temporal behavior of the K_s time-series, the variability is distinguished as either periodic, long time-scale or irregular. This temporal behavior coupled with the behavior of stellar colors is used to assign a dominant variability mechanism. A new period-searching algorithm finds periodic signals in 32 variable stars with periods between 0.49 to 92 days. The chief mechanism driving the periodic variability for 18 stars is rotational modulation of cool starspots while 3 periodically vary due to accretion-induced hot spots. The time-series for six variable stars contains discrete periodic "eclipse-like" features with periods ranging from 3 to 8 days. These features may be asymmetries in the circumstellar disk, potentially sustained or driven by a proto-planet at or near the co-rotation radius. Aperiodic, long time-scale variations in stellar flux are identified in the time-series for 31 variable stars with time-scales ranging from 64 to 790 days. The chief mechanism driving long time-scale variability is variable extinction or mass accretion rates. The majority of the variable stars (40) exhibit sporadic, aperiodic variability over no discernable time-scale. No chief variability mechanism could be identified for these variable stars.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Plavchan, Peter0000-0002-8864-1667
White, Russel J.0000-0001-5313-7498
Additional Information:© 2014 American Astronomical Society. Received 2012 May 22; accepted 2013 July 8; published 2014 February 6. We express our thanks to our anonymous referee for conversation and comments. We also express our thanks to Mary Barsony for her many insightful questions and suggestions. 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 has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The authors would like to acknowledge the Infrared Processing and Analysis Center’s Visiting Graduate Student program for providing the opportunity and funding for this publication.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Infrared Processing and Analysis Center Visiting Graduate Student ProgramUNSPECIFIED
Subject Keywords:methods: statistical; stars: individual (ρ Ophiuchus); stars: infrared; stars: pre-main sequence; stars: variables: general
Issue or Number:1
Record Number:CaltechAUTHORS:20131001-090523081
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Official Citation:Periodic and Aperiodic Variability in the Molecular Cloud ρ Ophiuchus J. Robert Parks et al. 2014 ApJS 211 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41588
Deposited By: Ruth Sustaita
Deposited On:02 Oct 2013 18:06
Last Modified:09 Mar 2020 13:19

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