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On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae

Richey-Yowell, Tyler and Kao, Melodie M. and Pineda, J. Sebastian and Shkolnik, Evgenya L. and Hallinan, Gregg (2020) On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae. Astrophysical Journal, 903 (1). Art. No. 74. ISSN 1538-4357. doi:10.3847/1538-4357/abb826.

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Photometric variability attributed to cloud phenomena is common in L/T transition brown dwarfs. Recent studies show that such variability may also trace aurorae, suggesting that localized magnetic heating may contribute to observed brown dwarf photometric variability. We assess this potential correlation with a survey of 17 photometrically variable brown dwarfs using the Karl G. Jansky Very Large Array at 4–8 GHz. We detect quiescent and highly circularly polarized flaring emission from one source, 2MASS J17502484-0016151, which we attribute to auroral electron cyclotron maser emission. The detected auroral emission extends throughout the frequency band at ~5–25σ, and we do not detect evidence of a cutoff. Our detection confirms that 2MASS J17502484-0016151 hosts a magnetic field strength of ≥2.9 kG, similar to those of other radio-bright ultracool dwarfs. We show that Hα emission continues to be an accurate tracer of auroral activity in brown dwarfs. Supplementing our study with data from the literature, we calculate the occurrence rates of quiescent emission in L dwarfs with low- and high-amplitude variability and conclude that high-amplitude optical and infrared variability does not trace radio magnetic activity in L dwarfs.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Richey-Yowell, Tyler0000-0003-1290-3621
Kao, Melodie M.0000-0001-5125-1414
Pineda, J. Sebastian0000-0002-4489-0135
Shkolnik, Evgenya L.0000-0002-7260-5821
Hallinan, Gregg0000-0002-7083-4049
Additional Information:© 2020 The American Astronomical Society. Received 2020 March 25; revised 2020 September 10; accepted 2020 September 10; published 2020 November 3. The authors would like to thank the anonymous referee for an insightful report. T.R.Y. and M.M.K. would like to thank Cameron Voloshin for consulting on the statistics of this study. T.R.Y. would additionally like to thank Danny Jacobs, Adam Beardsley, and Judd Bowman for useful discussions and CASA help. Support for this work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51411.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555; and by the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work is based on observations made with the NSF's Karl G. Jansky Very Large Array (VLA). This research has made use of the SIMBAD and VizieR databases, operated at CDS, Strasbourg, France; and the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Software: CASA (McMullin et al. 2007), Astropy (Price-Whelan et al. 2018), Matplotlib (Hunter 2007), Numpy (van der Walt et al. 2011), Scipy (Jones et al. 2001), MATLAB (MATLAB 2018).
Group:Astronomy Department
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF2-51411.001-A
National Radio Astronomy ObservatoryUNSPECIFIED
Subject Keywords:Brown dwarfs ; L dwarfs ; Radio astronomy ; Radio observatories ; Clouds ; Radio continuum emission ; Radio sources
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Brown dwarfs (185); L dwarfs (894); Radio astronomy (1338); Radio observatories (1350); Clouds (258); Radio continuum emission (1340); Radio sources (1358)
Record Number:CaltechAUTHORS:20201104-145744682
Persistent URL:
Official Citation:Tyler Richey-Yowell et al 2020 ApJ 903 74
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106437
Deposited By: Tony Diaz
Deposited On:05 Nov 2020 00:34
Last Modified:16 Nov 2021 18:54

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