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Published 2011 | public
Book Section - Chapter

A Search for Periodic Optical Variability in Radio Detected Ultracool Dwarfs: A Consequence of a Magnetically-Driven Auroral Process?


A number of ultracool dwarfs have been unexpectedly detected as radio sources in the last decade, four of which have been found to be producing periodic pulses. More recently, two of these pulsing dwarfs have also been found to be periodically variable in broadband optical photometry. The detected periods match the periods of the radio pulses which have previously been associated with the rotation period of the dwarf. For one of these objects, it has also been established that the optical and radio periodic variability are possibly linked, being a consequence of magnetically-driven auroral processes. In order to investigate the ubiquity of the periodic optical variability in radio detected sources, the GUFI instrument (Galway Ultra Fast Imager) was commissioned on the 1.8m Vatican Advanced Technology Telescope, on Mt. Graham, Arizona, and has been obtaining data for the past eighteen months. More than two hundred hours of multi-epoch photometric monitoring observations of radio detected ultracool dwarfs have been completed. We present initial results confirming optical periodic variability for four of this sample, three of which have been newly confirmed using GUFI.

Additional Information

© 2011 Astronomical Society of the Pacific. LKH gratefully acknowledges the support of the Science Foundation Ireland (Grant Number 07/RFP/PHYF553). We thank the VATT team for their help and guidance, especially Dave Harvey, Ned Franz and Ken Duffek. LKH would also like to personally thank Dr. Mark Lang for his constant assistance, in addition to the staff of the NRAO who provided significant support when LKH was conducting some of his work during his appointment as an NRAO graduate intern.

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August 19, 2023
January 13, 2024