The peculiar dipping events in the disk-bearing young-stellar object EPIC 204278916

TL;DR

This paper analyzes irregular and periodic dimming events in a young stellar object, suggesting they are caused by a warped disk or transiting cometary objects, with implications for similar young stars.

Contribution

It provides a detailed analysis of the light curve of EPIC 204278916 and proposes novel explanations for its dipping events involving disk warping or cometary transits.

Findings

Irregular dimmings up to 65% lasting ~25 days

Periodic variability attributed to stellar rotation

Possible causes include warped disk or transiting objects

Abstract

EPIC 204278916 has been serendipitously discovered from its K2 light curve which displays irregular dimmings of up to 65% for ~25 consecutive days out of 78.8 days of observations. For the remaining duration of the observations, the variability is highly periodic and attributed to stellar rotation. The star is a young, low-mass (M-type) pre-main-sequence star with clear evidence of a resolved tilted disk from ALMA observations. We examine the K2 light curve in detail and hypothesise that the irregular dimmings are caused by either a warped inner-disk edge or transiting cometary-like objects in either circular or eccentric orbits. The explanations discussed here are particularly relevant for other recently discovered young objects with similar absorption dips.