Evidence for Centrifugal Breakout around the Young M Dwarf TIC 234284556

Abstract

Magnetospheric clouds have been proposed as explanations for depth-varying dips in the phased light curves of young, magnetically active stars such as σ Ori E and RIK-210. However, the stellar theory that first predicted magnetospheric clouds also anticipated an associated mass-balancing mechanism known as centrifugal breakout for which there has been limited empirical evidence. In this paper, we present data from the Transiting Exoplanet Survey Satellite, Las Cumbres Observatory, All-Sky Automated Survey for Supernovae, and Veloce on the 45 Myr M3.5 star TIC 234284556, and propose that it is a candidate for the direct detection of centrifugal breakout. In assessing this hypothesis, we examine the sudden (~1 day timescale) disappearance of a previously stable (~1 month timescale) transit-like event. We also interpret the presence of an anomalous brightening event that precedes the disappearance of the signal, analyze rotational amplitudes and optical flaring as a proxy for magnetic activity, and estimate the mass of gas and dust present immediately prior to the potential breakout event. After demonstrating that our spectral and photometric data support a magnetospheric cloud and centrifugal breakout model and disfavor alternate scenarios, we discuss the possibility of a coronal mass ejection or stellar wind origin of the corotating material and we introduce a reionization mechanism as a potential explanation for more gradual variations in eclipse parameters. Finally, after comparing TIC 234284556 with previously identified "flux-dip" stars, we argue that TIC 234284556 may be an archetypal representative of a whole class of young, magnetically active stars.