相关论文: Where are the hot ion lines in classical T Tauri s…

We have analyzed GHRS data of eight Classical T Tauri stars (CTTSs) and one Weak T Tauri star (WTTS). The GHRS data consist of an spectral range 40 A wide centered on 2800 A. For 4 of the CTTS we have nearly simultaneous optical…

Spectroscopy of the infrared He I (10830A) line with KECK/NIRSPEC and IRTF/CSHELL, and of the ultraviolet C III (977A) and O VI (1032A) emission with FUSE reveals that the classical T Tauri star TW Hydrae exhibits P Cygni profiles, line…

We present multidimensional non-LTE radiative transfer models of hydrogen and helium line profiles formed in the accretion flows and the outflows near the star-disk interaction regions of classical T Tauri stars (CTTSs). The statistical…

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…

We have analyzed GHRS data of eight CTTS and one WTTS. The GHRS data consists of spectral ranges 40 A wide centered on 1345, 1400, 1497, 1550, and 1900 A. These UV spectra show strong SiIV, and CIV emission, and large quantities of sharp…

We present the emission line profile models of hydrogen and helium based on the results from axisymmetric magnetohydrodynamics (MHD) simulations of the wind formed near the disk-magnetosphere boundary of classical T Tauri stars (CTTSs). We…

Ultraviolet observations of classical T Tauri Stars (cTTSs) have shown that there is a hot (Te ~ 80,000 K) and dense (ne ~ 1e10 cm-3) component associated with the large scale jet. This hot component is formed very close to the base of the…

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…

The C II] feature at ~2325 Angstrom is very prominent in the spectra of T Tauri stars (TTSs). This feature is a quintuplet of semiforbidden transitions excited at electron temperatures around 10,000 K that, together with the nearby Si II]…

RY Tau is a rapidly rotating Classical T Tauri star observed close to edge-on. The combination of new HST/STIS observations obtained in 2001 with HST/GHRS Archive data from 1993 has allowed us to get, for the first time, information on the…

We present the results of an analysis of ultraviolet observations of T Tauri Stars (TTS). By analysing emission measures taken from the literature we derive rates of ionizing photons from the chromospheres of 5 classical TTS in the range…

We survey fluorescent H2 emission in HST/STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau, RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41-209…

Previous studies of young stellar objects (YSOs) have uncovered a number of associated parsec-scale optical outflows, the majority of which are driven by low-mass, embedded Class I sources. Here we examine more evolved Classical T Tauri…

We use FUV spectra of 36 T Tauri stars, predominately from $\textit{Hubble Space Telescope}$'s ULLYSES program, to examine the kinematic properties of fluorescent H$_2$ emission lines for evidence of disk outflows. Leveraging improvements…

We detect near-infrared H2 emission in DG Tau using the Infrared Camera and Spectrograph (IRCS) on the 8.2-m SUBARU telescope. The spectra obtained along the jet axis show that the centroidal position of the 1-0 S(1) emission is offset by…

Radiative transfer modelling offers a powerful tool for understanding the enigmatic hydrogen emission lines from T Tauri stars. This work compares optical and near-IR spectroscopy of 29 T Tauri stars with our grid of synthetic line…

We study an anomaly in the X-ray flux (or luminosity) ratio between the OVII 21.6-22.1A triplet and the OVIII Lya line seen in classical T Tauri stars (CTTS). This ratio is unusually high when compared with ratios for main-sequence and…

We perform local excitation calculations to obtain line opacities and emissivity ratios and compare them with observed properties of H, He I, O I, Ca II, and Na I lines to determine the density, temperature, and photon ionization rate. We…

We studied rotational modulation of the radial velocities of narrow emission lines in four classical T Tauri stars. We found that the previously declared shift of the mean velocity of neutral and ionized helium lines relative to the mean…

High-resolution X-ray spectra of high-mass stars and low-mass T-Tauri stars obtained during the first year of the Chandra mission are providing important clues about the mechanisms which produce X-rays on very young stars. For zeta Puppis…