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arXiv · 1902.08152

Deep Long Asymmetric Occultation in EPIC 204376071

S. Rappaport·G. Zhou·A. Vanderburg·A. Mann·M. H. Kristiansen·K. Olah·T. L. Jacobs·E. Newton·M. R. Omohundro·D. LaCourse·H. M. Schwengeler·I. A. Terentev·D. W. Latham·A. Bieryla·M. Soares-Furtado·L. G. Bouma·M. J. Ireland·J. Irwin
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Abstract

We have discovered a young M star of mass $0.16\,M_\odot$ and radius $0.63\,R_\odot$, likely in the Upper Sco Association, that exhibits only a single $80\%$ deep occultation of 1-day duration. The star has frequent flares and a low-amplitude rotational modulation, but is otherwise quiet over 160 days of cumulative observation during K2 Campaigns C2 and C15. We discuss how such a deep eclipse is not possible by one star crossing another in any binary or higher-order stellar system in which no mass transfer has occurred. The two possible explanations we are left with are (1) orbiting dust or small particles (e.g., a disk bound to a smaller orbiting body, or unbound dust that emanates from such a body); or (2) a transient accretion event of dusty material near the corotation radius of the star. In either case, the time between such occultation events must be longer than $\sim$80 days. We model a possible orbiting occulter both as a uniform elliptically shaped surface (e.g., an inclined circular disk) and as a `dust sheet' with a gradient of optical depth behind its leading edge. The required masses in such dust features are then $\gtrsim 3 \times 10^{19}$ g and $\gtrsim 10^{19}$ g, for the two cases, respectively.

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S. Rappaport, G. Zhou, A. Vanderburg, A. Mann, M. H. Kristiansen, K. Olah, T. L. Jacobs, E. Newton, M. R. Omohundro, D. LaCourse, H. M. Schwengeler, I. A. Terentev, D. W. Latham, A. Bieryla, M. Soares-Furtado, L. G. Bouma, M. J. Ireland, J. Irwin. 2019-02-21. Deep Long Asymmetric Occultation in EPIC 204376071. https://doi.org/10.1093/mnras/stz537

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