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A Zwicky Transient Facility Look at Optical Variability of Young Stellar Objects in the North America and Pelican Nebulae Complex

Hillenbrand, Lynne A. and Kiker, Thaddaeus J. and Gee, Miles and Lester, Owen and Braunfeld, Noah L. and Rebull, Luisa M. and Kuhn, Michael A. (2022) A Zwicky Transient Facility Look at Optical Variability of Young Stellar Objects in the North America and Pelican Nebulae Complex. Astronomical Journal, 163 (6). Art. No. 263. ISSN 0004-6256. doi:10.3847/1538-3881/ac62d8.

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We present a study of 323 photometrically variable young stellar objects that are likely members of the North America and Pelican nebulae star-forming region. To do so, we utilize over two years of data in the g and r photometric bands from the Zwicky Transient Facility. We first investigate periodic variability, finding 46 objects (∼15% of the sample) with significant periods that phase well and can be attributed to stellar rotation. We then use the quasiperiodicity (Q) and flux asymmetry (M) variability metrics to assign morphological classifications to the remaining aperiodic light curves. Another ∼39% of the variable star sample beyond the periodic (low Q) sources are also flux-symmetric, but with a quasiperiodic (moderate Q) or stochastic (high Q) nature. Concerning flux-asymmetric sources, our analysis reveals ∼14% bursters (high negative M) and ∼29% dippers (high positive M). We also investigate the relationship between variability slopes in the g versus g − r color–magnitude diagram, and the light-curve morphological classes. Burster-type objects have shallow slopes, while dipper-type variables tend to have higher slopes that are consistent with extinction-driven variability. Our work is one of the earliest applications of the Q and M metrics to ground-based data. We therefore contrast the Q values of high-cadence and high-precision space-based data, for which these metrics were designed, with Q determinations resulting from degraded space-based light curves that have the cadence and photometric precision characteristic of ground-based data.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper Itempython code used to calculate the Q and M variability metrics
Kiker, Thaddaeus J.0000-0002-2363-2487
Rebull, Luisa M.0000-0001-6381-515X
Kuhn, Michael A.0000-0002-0631-7514
Alternate Title:A ZTF Look at Optical Variability of Young Stellar Objects in the North America and Pelican Nebulae Complex
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 November 1; revised 2022 March 16; accepted 2022 March 17; published 2022 May 12. We thank Leah Seignourel, Pietro Romussi, and Korgan Atillasoy for their participation in early discussions about this work. We also thank John Bredall, Katja Poppenhaeger, and Hans Moritz Günther for assistance with various Python questions, as well as Travis Austin for assistance with recovering a significant amount of our work from a damaged virtual machine disk. Ann Marie Cody provided the K2 light curves that form the basis of Appendix C, as well as valuable advice concerning Q. This work is based on data from the Zwicky Transient Facility, which is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. We thank the referee for a careful look at our methods and results. Facilities: P48:ZTF - , IRSA. - Software: NumPy (Harris et al. 2020), Matplotlib (Hunter 2007), Pandas (McKinney 2010), Astropy (Astropy Collaboration et al. 2013, 2018), SciPy (Virtanen et al. 2020), and uncertainties (Lebigot 2010).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
ZTF partner institutionsUNSPECIFIED
Subject Keywords:Young star clusters; Pre-main sequence stars; T Tauri stars; Slow irregular variable stars; Stellar rotation; Time domain astronomy
Issue or Number:6
Classification Code:Unified Astronomy Thesaurus concepts: Young star clusters (1833); Pre-main sequence stars (1290); T Tauri stars (1681); Slow irregular variable stars (1466); Stellar rotation (1629); Time domain astronomy (2109)
Record Number:CaltechAUTHORS:20220512-561465000
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Official Citation:Lynne A. Hillenbrand et al 2022 AJ 163 263
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114709
Deposited By: George Porter
Deposited On:13 May 2022 17:43
Last Modified:13 May 2022 17:43

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