Classical T Tauri stars: accretion, wind, dust

Petr Petrov

doi:10.31059/aat.vol2.iss1.pp1-8

Abstract

Classical T Tauri stars (CTTS) are at the early evolutionary stage when the processes of planet formation take place in the surrounding accretion disks. Most of the observed activity in CTTS is due to magnetospheric accretion and wind flows. Observations of the accreting gas flows and appearance of the line-dependent veiling of the photospheric spectrum in CTTS are considered. Evidence for the dusty wind causing the observed irregular variability of CTTS is presented. Photometric and spectroscopic monitoring of two CTTS, RY Tau and SU Aur, has been carried out atthe Crimean Astrophysical Observatory since 2013 aimed at studying the dynamics of accretion and wind flows on time scales from days to years. The observed variations in the dynamical parameters may be caused by changes in the accretion rate and in the global magnetic fields of CTTS.

Highlights

T Tauri stars were first investigated and distinguished into a new type of variables 75 years ago (Joy, 1945)
Contrary to the more massive (> 2 M ) young stars related to the class of Herbig Ae/Be stars (HAeBe), classical T Tauri stars (CTTS) have convective envelopes and, strong magnetic fields and pronounced “magnetic-type” activity, in particular, X-ray emission (Pevtsov et al, 2003)
Contrary to the compact objects where the fall time of matter is measured in milliseconds or minutes, this time is about a day in CTTS

Summary

Introduction

T Tauri stars were first investigated and distinguished into a new type of variables 75 years ago (Joy, 1945). Contrary to the more massive (> 2 M ) young stars related to the class of Herbig Ae/Be stars (HAeBe), CTTS have convective envelopes and, strong magnetic fields and pronounced “magnetic-type” activity, in particular, X-ray emission (Pevtsov et al, 2003). Contrary to the compact objects where the fall time of matter is measured in milliseconds (neutron stars) or minutes (white dwarfs incorporated in cataclysmic variables), this time is about a day in CTTS This allows one to observe motions of gas flows with sufficient time resolution and carry out a detailed comparison of the observed phenomena with what yields the numerical modeling of magnetohydrodynamic (MHD) processes

III G7-K0 IV K1 IV K1 K5 IV K6 IV K7 V

Accretion and veiling of the photospheric spectrum

Wind and circumstellar dust

Dynamics of accretion and wind flows

Conclusions