Deep long asymmetric occultation in EPIC 204376071

Rappaport, S. and Zhou, G. ORCID: and Vanderburg, A. and Mann, A. and Kristiansen, M. H. and Olah, K. and Jacobs, T. L. and Newton, E. and Omohundro, M. R. and LaCourse, D. and Schwengeler, H. M. and Terentev, I. A. and Latham, D. W. and Bieryla, A. and Soares-Furtado, M. and Bouma, L. G. and Ireland, M. J. and Irwin, J. (2019) Deep long asymmetric occultation in EPIC 204376071. Monthly Notices of the Royal Astronomical Society, 485 (2). pp. 2681-2693. ISSN 0035-8711

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We have discovered a young M star of mass 0.16M(circle dot) and radius 0.63 R-circle dot, likely in the Upper Sco Association, that exhibits only a single 80 per cent deep occultation of 1-d duration. The star has frequent flares and a low-amplitude rotational modulation, but is otherwise quiet over 160 d 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 disc 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 similar to 80 d. We model a possible orbiting occulter both as a uniform elliptically shaped surface (e.g. an inclined circular disc) and as a 'dust sheet' with a gradient of optical depth behind its leading edge. The required masses in such dust features are then greater than or similar to 3 x 10(19) g and greater than or similar to 10(19) g, for the two cases, respectively.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 11 Jan 2022 04:06
Last Modified: 13 Jan 2022 09:13
Uncontrolled Keywords: stars: flare; stars: late-type; stars: low-mass; stars: pre-main-; sequence; (stars:) starspots; Astrophysics - Solar and Stellar; Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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