Simulations of the periodic flaring rate on YY Gem

TL;DR

This paper models the periodic flaring rate of YY Gem using 2.5D MHD simulations, showing magnetic reconnection modulated by trapped magnetoacoustic waves as the cause of observed periodicity.

Contribution

It introduces a new MHD simulation-based model explaining YY Gem's flaring periodicity through magnetic reconnection driven by stellar rotation and wave modulation.

Findings

Reproduces the observed 48-minute flaring period.

Shows magnetic reconnection is modulated by trapped magnetoacoustic waves.

Provides an empirical formula linking period to stellar parameters.

Abstract

The binary YY Gem shows many interesting properties, one of which is the periodicity in its flaring rate. The period, which is about $48 \pm 3$ min, was ever interpreted in terms of the oscillation of a filament. In this paper, we propose a new model to explain this phenomenon by means of 2.5-dimensional MHD numerical simulations. It is found that magnetic reconnection is induced as the coronal loops rooted on both stars inflate and approach each other, which is driven by the differential stellar rotation. The magnetic reconnection is modulated by fast-mode magnetoacoustic waves which are trapped between the surfaces of the two stars, so that the reconnection rate presents a periodic behaviour. With the typical parameters for the binary system, the observed period can be reproduced. We also derive an empirical formula to relate the period of the flaring rate to the coronal temperature and density, as well as the magnetic field.