English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The evolution of protoplanetary disks is believed to be driven largely byangular momentum transport resulting from magnetized disk winds and turbulentviscosity. The ionization of the disk that is essential for these processes hasbeen thought due to host star coronal X-rays but could also arise fromenergetic particles produced by coronal flares or by travelling shock waves andadvected by the stellar wind. We have performed test-particle numericalsimulations of energetic protons propagating into a realistic T~Tauri stellarwind, including a superposed small-scale magnetostatic turbulence. Theisotropic (Kolmogorov power spectrum) turbulent component is synthesised alongthe individual particle trajectories. We have investigated the energy range$[0.1 - 10]$ GeV, consistent with expectations from {\it Chandra} X-rayobservations of large flares on T~Tauri stars and with recent indications bythe {\it Herschel} Space Observatory of a significant contribution of energeticparticles to the disk ionization of young stars. In contrast with a previoustheoretical study finding dominance of energetic particles over X-ray in theionization throughout the disk, we find that the disk ionization is likelydominated by X-rays over much of its area except within narrow regions whereparticles are channeled onto the disk by the strongly-tangled and turbulentmagnetic field. The radial thickness of such regions is $\sim 5$ stellar radiiclose to the star and broadens with increasing radial distance. This likelycontinues out to large distances from the star ($10$ AU or greater) whereparticles can be copiously advected and diffused by the turbulent wind.

Mottled protoplanetary disk ionization by magnetically-channeled T Tauri star energetic particles