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Published February 1, 2017 | Submitted + Published
Journal Article Open

A Transient Transit Signature Associated with the Young Star RIK-210


We find transient transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial resolution imaging revealed that the star is single and radial velocity monitoring indicated that the dimming events cannot be due to an eclipsing stellar or brown dwarf companion. Archival and follow-up photometry suggest the dimming events are transient in nature. The variable morphology of the dimming events suggests they are not due to a single spherical body. The ingress of each dimming event is always shallower than egress, as one would expect for an orbiting body with a leading tail. The dimming events are periodic and synchronous with the stellar rotation. However, we argue it is unlikely the dimming events could be attributed to anything on the stellar surface based on the observed depths and durations. Variable obscuration by a protoplanetary disk is unlikely on the basis that the star is not actively accreting and lacks the infrared excess associated with an inner disk. Rather, we explore the possibilities that the dimming events are due to magnetospheric clouds, a transiting protoplanet surrounded by circumplanetary dust and debris, eccentric orbiting bodies undergoing periodic tidal disruption, or an extended field of dust or debris near the corotation radius.

Additional Information

© 2017 The American Astronomical Society. Received 2016 October 18; revised 2016 December 8; accepted 2016 December 9; published 2017 January 27. The authors thank Todd Boroson for allocation of LCOGT director's discretionary time and Nikolaus Volgenau for assistance scheduling observations. We thank the anonymous referee for a thorough review, Saul Rappaport for helpful comments on an early draft and for providing the Fisher matrix analysis of the RVs, Jim Fuller for bringing σ Ori E to our attention, Eugene Chiang, Konstantin Batygin, Kat Deck, Brad Hansen, and Lee Hartmann for helpful discussions, as well as Norio Narita and John Livingston for attempting follow-up observations. T.J.D. is supported by an NSF Graduate Research Fellowship under Grant DGE1144469. E.A.P. is supported through a Hubble Fellowship. A.M.C.'s research was supported by an appointment to the NASA Postdoctoral Program at the NASA Ames Research Center, administered by Universities Space Research Association under contract with NASA. B.J.F. was supported by the National Science Foundation Graduate Research Fellowship under grant No. 2014184874. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This paper includes data collected by the Kepler/K2 mission, funded by the NASA Science Mission directorate and obtained from the Mikulski Archive for Space Telescopes (MAST), supported by the NASA Office of Space Science via grant NNX09AF08G. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Attached Files

Published - David_2017_ApJ_835_168.pdf

Submitted - 1612.03907v1.pdf


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August 19, 2023
October 24, 2023