Related papers: Modeling T Tauri Winds from He I 10830 Profiles
We present long-slit spectroscopy and spectro-astrometry of HeI 1.083 micron emission in the T Tauri star, DG Tau. We identify three components in the HeI feature: (1) a blueshifted emission component atv -200 km s^-1, (2) a bright emission…
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…
How T Tauri stars remain slowly rotating while still accreting material is a long-standing puzzle. Current models suggest that these stars may lose angular momentum through magnetospheric ejections of disk material (MEs) and…
We present radiative transfer models of the circumstellar environment of classical T Tauri stars, concentrating on the formation of the H-alpha emission. The wide variety of line profiles seen in observations are indicative of both inflow…
Intermediate dispersion spectroscopic observations of 37 Herbig Ae/Be stars reveal that the equivalent widths of their [OI] 6300A and Halpha emission lines, are related to their near-infrared colours in the same fashion as the T-Tauri…
Recent spectropolarimetric observations suggest that young low-mass stars such as classical T Tauri stars (CTTSs) possess relatively strong (~kG) magnetic field. This supports a scenario in which the final accretion onto the stellar surface…
Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. Here, we analyze high-resolution ($\Delta v \sim$ 7 kms$^{-1}$) optical spectra from a sample…
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…
Disk winds are an important mechanism for accretion and disk evolution around young stars. The accreting intermediate-mass T-Tauri star RY Tau has an active jet and a previously known disk wind. Archival optical and new near-infrared…
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…
Stellar winds may be important for angular momentum transport from accreting T Tauri stars, but the nature of these winds is still not well-constrained. We present some simulation results for hypothetical, hot (~1e6 K) coronal winds from T…
The He I 1 micron line is a high excitation line which allows us to probe the innermost regions of protostellar disks, and to trace both accreting and outflowing material. We use X-Shooter observations of a sample of 107 young stars in the…
Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. We report the first high-resolution ($\Delta v\sim$6\kms) analysis of [S II] $\lambda$4068,…
For the first time in a classical T Tauri star, we are able to trace an accretion event signaled by an hour-long enhancement of X-rays from the accretion shock and revealed through substantial sequential changes in optical emission line…
High inclination black hole X-ray binaries exhibit blueshifted ionized absorption lines from disk winds, whose launching mechanism is still in debate. The lines are predominantly observed in the high/soft state and disappear in the low/hard…
We carried out optical high-resolution spectroscopy of T Tauri stars using the Subaru Telescope. Using archived data from the Keck Telescope and the Very Large Telescope, we detected forbidden lines of [S II] at 4069 A, in addition to those…
The HeII (1640 A) line and the resonance doublet of NV (UV1) provide a good diagnostic tool to constrain the excitation mechanism of hot (Te>40,000K) atmospheric/magnetospheric plasmas in T Tauri stars (TTSs). Making use of the data…
We present near-infrared spectra of the excess continuum emission from the innermost regions of classical T Tauri disks. In almost all cases, the shape of the excess is consistent with that of a single-temperature blackbody with T ~ 1400 K,…
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 examine He I 10830 profile morphologies for a sample of 56 Herbig Ae/Be stars (HAEBES). We find significant differences between HAEBES and CTTSs in the statistics of both blue-shifted absorption (i.e. mass outflows) and red-shifted…