Evidence for giant interacting coronal streamers in a pre-main-sequence binary system

TL;DR

This study reports the first VLBI detection of solar-like extended coronal streamers in a pre-main-sequence binary system, revealing magnetic interactions and relativistic electron acceleration in young stars.

Contribution

It provides the first direct imaging evidence of giant coronal streamers in T Tauri stars, challenging existing theories about magnetic structure formation in fully convective stars.

Findings

Detection of extended coronal streamers in T Tauri stars

Observation of magnetic reconnection during stellar rotation

Synchrotron emission indicating relativistic electrons

Abstract

Here we report on the VLBI discovery of solar-like extended streamers anchored on the two weak-line T Tauri stars of the binary system V773 Tau A. Covering the interbinary distance the 20 stellar radii extended streamers enter in collision during each stellar rotation with consequent occurrence of magnetic reconnection. Thermal electrons confined in the streamers become accelerated to relativistic speeds and emit synchrotron emission in the radio band making the magnetic streamers "visible" in the VLBI images. This is different from the solar case where the emission from the streamers is just scattered photospheric light that would never be observable in distant objects. Evidence of extended solar-like streamers in T Tauri stars, thought to be fully convective, or nearly fully convective objects, indicates that the tachoclinal layer, in this case either not existing at all or buried very deeply, is not relevant for the formation of such solar-like magnetic structures.