Ionization and heating by X-rays and cosmic rays

Autor(en)

Manuel Güdel

Abstrakt

High-energy radiation from the central T Tauri and protostars plays an important role in shaping protoplanetary disks and influences their evolution. Such radiation, in particular X-rays and extreme-ultraviolet (EUV) radiation, is predominantly generated in unstable stellar magnetic fields (e.g., the stellar corona), but also in accretion hot spots. Even jets may produce X-ray emission. Cosmic rays, i.e., high-energy particles either from the interstellar space or from the star itself, are of crucial importance. Both highenergy photons and particles ionize disk gas and lead to heating. Ionization and heating subsequently drive chemical networks, and the products of these processes are accessible through observations of molecular line emission. Furthermore, ionization supports the magnetorotational instability and therefore drives disk accretion, while heating of the disk surface layers induces photoevaporative flows. Both processes are crucial for the dispersal of protoplanetary disks and therefore critical for the time scales of planet formation. This chapter introduces the basic physics of ionization and heating starting from a quantum mechanical viewpoint, then discusses relevant processes in astrophysical gases and their applications to protoplanetary disks, and finally summarizes some properties of the most important high-energy sources for protoplanetary disks. 14^th Lecture from Summer School "Protoplanetary Disks: Theory and Modelling Meet Observations"

Organisation(en)

Institut für Astrophysik

DOI

https://doi.org/10.1051/epjconf/201510200015

Publikationsdatum

09-2015

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

ASJC Scopus Sachgebiete

Physics and Astronomy(all)

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/ionization-and-heating-by-xrays-and-cosmic-rays(38e22d7d-9420-4903-ad91-9f699ea44afd).html