Structure of the shock at the surface of CTTS

TL;DR

This paper models the steady-state structure and spectrum of the accretion shock at the surface of T Tauri stars, incorporating gas motion effects to understand spectral features and cooling rates.

Contribution

It introduces a numerical simulation of the shock structure at CTTS surfaces that includes gas motion effects like advection and Doppler shifts, advancing stellar atmosphere modeling.

Findings

Helium and hydrogen lines show red-shifted absorption at high pre-shock densities.

Broadening of lines is significantly affected by the Stark effect.

The spectrum and cooling rates of the shocked gas are quantitatively characterized.

Abstract

A steady-state structure and spectrum of the accretion zone at the surface of T Tauri stars are numerically simulated. This modeling uses well-developed methods of the theory of stellar atmospheres with inclusion of the effects of the gas motion (advection and the doppler shift of the lines). The spectrum $I_{\nu}(\mu)$ and cooling rate of shocked gas are calculated. It is found that at the pre-shock densities $N_0>10^{13}$ cm$^{-3}$ helium and hydrogen lines show a red-shifted absorption, significantly broadened by the Stark effect.