Related papers: Structure and Dynamics of the Accretion Process an…

Pre-main-sequence stars are observed to be surrounded by both accretion flows and some kind of wind or jet-like outflow. Recent work by Matt and Pudritz has suggested that if classical T Tauri stars exhibit stellar winds with mass loss…

In a high dispersion 1 micron survey of 39 classical T Tauri stars veiling is detected in 80%, and He I 10830 and Pgamma line emission in 97% of the stars. On average, the 1 micron veiling exceeds the level expected from previously…

Classical T Tauri stars (CTTS) are surrounded by actively accreting disks. According to current models material falls along the magnetic field lines from the disk with more or less free-fall velocity onto the star, where the plasma heats up…

We present high resolution X-ray spectra of the X-ray bright classical T Tauri star, TW Hydrae, covering the wavelength range of 1.5-25 AA. The differential emission measure derived from fluxes of temperature-sensitive emission lines shows…

Context. High resolution X-ray observations of classical T Tauri stars (CTTSs) show a soft X-ray excess due to high density plasma (n_e=10^11-10^13 cm^-3). This emission has been attributed to shock-heated accreting material impacting onto…

We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published…

Classical T Tauri stars (CTTSs) accrete matter from the inner edge of their surrounding circumstellar disks. The impact of the accretion material on the stellar atmosphere results in a strong shock, which causes emission from the X-ray to…

Classical T Tauri stars are surrounded by a circumstellar disk from which they are accreting material. This process is essential in the formation of Sun-like stars. Although often described with simple and static models, the accretion…

The problem on heating the atmospheres of T Tauri stars by radiation from an accretion shock has been solved. The structure and radiation spectrum of the emerging so-called hot spot have been calculated in the LTE approximation. The…

This article summarizes the processes of high-energy emission in young stellar objects. Stars of spectral type A and B are called Herbig Ae/Be (HAeBe) stars in this stage, all later spectral types are termed classical T Tauri stars (CTTS).…

Classical T Tauri stars with ages of less than 10 Myr possess accretion discs. Magnetohydrodynamic processes at the boundary between the disc and the stellar magnetosphere control the accretion and ejections gas flows. We carried out a long…

We perform three-dimensional magnetohydrodynamic simulations of magnetospheric accretion in a T Tauri star to study the accretion and wind structures in the close vicinity of the star. The gas accreting onto the star consists of the gas…

The mass outflows in T Tauri stars (TTS) are thought to be an effective mechanism to remove angular momentum during the pre-main-sequence contraction of a low-mass star. The most powerful winds are observed at the FUor stage of stellar…

We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature T_e, electron…

We present time-series, high-resolution optical spectroscopy of the eccentric T Tauri binary TWA 3A. Our analysis focuses on variability in the strength and structure of the accretion tracing emission lines H alpha and He I 5876A. We find…

We report here results of spectropolarimetric observations of the ~8Myr classical TTauri star (cTTS) TWHya carried out with ESPaDOnS at the Canada-France-Hawaii Telescope (CFHT) in the framework of the `Magnetic Protostars and Planets'…

For Classical T Tauri Stars (CTTSs), the resonance lines of N V, Si IV, and C IV, as well as the He II 1640 A line, act as diagnostics of the accretion process. Here we assemble a large high-resolution dataset of these lines in CTTSs and…

Fourteen models are calculated with the shock velocity ranging from 200 to 330 km s$^{-1}$ and pre-shock hydrogen nucleon density ranging from $2.5\times 10^{12}$ to $4\times 10^{13}$ cm$^{-3}$. Among them the summed emergent flux of all…

Measurements of masses and ages of young stars from their location in the HR diagram are limited by not only the typical observational uncertainties that apply to field stars, but also by large systematic uncertainties related to…

Spectral and photometric variability of the Classical T Tauri stars RY Tau and SU Aur from 2013 to 2022 is analyzed. We find that in SU Aur the H-alpha line's flux at radial velocity RV = -50 +- 7 km/s varies with a period P = 255 +- 5…