# Interacting Young M-dwarfs in Triple System -- Par 1802 Binary System Case Study

## TL;DR

This study investigates how a third companion in the Par 1802 triple system can induce tidal heating and mass transfer, explaining the observed temperature differences between the binary stars through detailed dynamical and evolutionary modeling.

## Contribution

The paper presents a novel dynamical and evolutionary model showing that mass transfer and tidal heating can account for temperature discrepancies in young binary stars influenced by a tertiary companion.

## Key findings

- Mass transfer and tidal heating explain temperature differences.
- Predicted orbital configuration of the tertiary companion.
- Dynamical evolution impacts pre-main-sequence stellar properties.

## Abstract

The binary star Par 1802 in the Orion Nebula presents an interesting puzzle in the field of stellar dynamics and evolution. Binary systems such as Par 1802 are thought to form from the same natal material and thus the stellar members are expected to have very similar physical attributes. However, Par 1802's stars have significantly different temperatures despite their identical (within $3\%$) masses of about $0.39$ solar mass. The leading proof-of-concept idea is that a third companion gravitationally induced the two stars to orbit closer than their Roche-limit, which facilitated heating through tidal effects. Here we expand on this idea and study the three-body dynamical evolution of such a system, including tidal and pre-main-sequence evolution. We also include tidal heating and mass transfer at the onset of Roche-limit Crossing. We show, as a proof-of-concept, that mass transfer combined with tidal heating can naturally explain the observed temperature discrepancy. We also predict the orbital configuration of the possible tertiary companion. Finally we suggest that the dynamical evolution of such a system has pervasive consequences. We expect an abundance of systems to undergo mass transfer during their pre-main-sequence time, which can cause temperature differences.