Characterising the magnetospheric accretion process of DF Tauri's primary

TL;DR

This study investigates the magnetospheric accretion process in the primary star of the binary system DF Tauri, demonstrating that it follows the typical dipolar magnetic funneling model despite the presence of a non-accreting companion.

Contribution

It applies high-resolution spectropolarimetric observations to confirm magnetospheric accretion in a binary system's primary star, expanding understanding beyond isolated stars.

Findings

The primary star exhibits typical magnetospheric accretion driven by a strong dipolar magnetic field.

Significant differences in magnetic topology exist between the two stars in the system.

The accretion process influences the magnetic field evolution and the secondary star's capture.

Abstract

The accretion process in young stellar objects (YSOs) is fundamental to the formation of stellar systems. This process governs the star's mass assembly, the transfer of angular momentum, and the shaping of the protoplanetary disc, thereby influencing planet formation. For classical T Tauri stars (cTTSs), which are low-mass YSOs, accretion is a well-understood process. Their strong, dipolar magnetic field truncates the disc at a few stellar radii. Material is then channelled along these magnetic field lines, creating accretion funnel flows that fall onto the star's surface. However, this paradigm, known as magnetospheric accretion, is limited to isolated stars. The accretion process in multiple systems has not yet been fully understood. This work is part of a series of studies designed to build a framework to understand the accretion process in multiple star systems. The specific goal here is to determine how the magnetospheric accretion model can be used to describe DF Tau, a binary system where only the primary star is accreting material. To investigate how accretion occurs in a system where a single star is orbited by a non-accreting stellar companion, we used a time series of high-resolution spectropolarimetric observations from the ESPaDOnS instrument. This allowed us to study the accretion-related emission line variability, the veiling, and the magnetic field topology of the primary star in the system. Our research concludes that the primary star of the DF Tau system undergoes typical magnetospheric accretion. This process is driven by a strong dipolar magnetic field, which funnels accreting material onto the stellar surface, creating an accretion shock. We also identified a significant difference in the magnetic topology of the two stars querying the influence of accretion of the evolution of the magnetic field, or capture of the secondary star.