Constraints on magnetospheric radio emission from Y dwarfs
Abstract
As a pilot study of magnetism in Y dwarfs, we have observed the three known infrared variable Y dwarfs WISE J085510.83−071442.5, WISE J140518.40+553421.4, and WISEP J173835.53+273258.9 with the NSF's Karl G. Jansky Very Large Array in the 4–8 GHz frequency range. The aim was to investigate the presence of non-bursting quiescent radio emission as a proxy for highly circularly polarized radio emission associated with large-scale auroral currents. Measurements of magnetic fields on Y dwarfs may be possible by observing auroral radio emission, and such measurements are essential for constraining fully convective magnetic dynamo models. We do not detect any pulsed or quiescent radio emission, down to rms noise levels of 7.2 µJy for WISE J085510.83−071442.5, 2.2 µJy for WISE J140518.40+553421.4, and 3.2 µJy for WISEP J173835.53+273258.9. The fractional detection rate of radio emission from T dwarfs is ∼10 per cent suggesting that a much larger sample of deep observations of Y dwarfs is needed to rule out radio emission in the Y dwarf population. We discuss a framework that uses an empirical relationship between the auroral tracer Hα emission and quiescent radio emission to identify brown-dwarf auroral candidates. Finally, we discuss the implications that Y dwarf radio detections and non-detections can have for developing a picture of brown dwarf magnetism and auroral activity.
Additional Information
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2019 May 6. Received 2019 May 6; in original form 2019 January 1. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for this work was provided by the National Science Foundation (NSF) through the Grote Reber Fellowship Program administered by Associated Universities, Inc./National Radio Astronomy Observatory; by a grant from the NSF Graduate Research Fellowship under Grant DGE-1144469; and by the NSF Grant AST-1654815. Support for this work was provided by the National Aeronautics and Space Administration (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.Attached Files
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Additional details
- Eprint ID
- 97419
- Resolver ID
- CaltechAUTHORS:20190725-125944897
- NSF Graduate Research Fellowship
- DGE-1144469
- NSF
- AST-1654815
- NASA Hubble Fellowship
- HST-HF2-51411.001-A
- NASA
- NAS5-26555
- Created
-
2019-07-25Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department