Laboratory unravelling of matter accretion in young stars

TL;DR

This study uses scaled laboratory experiments to investigate matter accretion in young stars, revealing how magnetic fields influence plasma dynamics and potentially reconcile observational discrepancies.

Contribution

It introduces the first laboratory experiments simulating collimated plasma accretion onto solids with magnetic fields, providing new insights into accretion processes.

Findings

Matter is laterally ejected upon impact and refocused by magnetic fields.

Ejected matter forms a plasma shell reducing X-ray emissions.

Results help reconcile differences in observed accretion rates.

Abstract

Accretion dynamics in the forming of young stars is still object of debate because of limitations in observations and modelling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is laterally ejected from the solid surface, then refocused by the magnetic field toward the incoming stream. Such ejected matter forms a plasma shell that envelops the shocked core, reducing escaped X-ray emission. This demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from X-ray and optical observations.