Related papers: Counterrotation in magnetocentrifugally driven jet…
We demonstrate that the 1D cylindrical version of the Grad-Shafranov equation is more rich than classical self-similar ones, and more suitable for the astrophysical jets we observe. In particular, it allows us to describe the central (and,…
We carried out axisymmetric simulations of disk accretion to a rapidly rotating magnetized star in the "propeller" regime. Simulations show that propellers may be "weak" (with no outflows), and "strong" (with outflows). Investigation of the…
Mean-field hydrodynamics advanced to clear explanations for the origin and properties of the global meridional flow in stellar convection zones. Qualitative arguments and analysis of basic equations both show that the meridional circulation…
Simulations of magnetohydrodynamics convection in slowly rotating stars predict anti-solar differential rotation (DR) in which the equator rotates slower than poles. This anti-solar DR in the usual $\alpha \Omega$ dynamo model does not…
Recently, differences in Doppler shifts across the base of four close classical T Tauri star jets have been detected with the HST in optical and near-ultraviolet (NUV) emission lines, and these Doppler shifts were interpreted as rotation…
We present a radial velocity study of the RY Tau jet-disk system, designed to determine whether a transfer of angular momentum from disk to jet can be observed. Many recent studies report on the rotation of T Tauri disks, and on what may be…
Star formation is usually accompanied by outflow phenomena. There is strong evidence that these outflows and jets are launched from the protostellar disk by magneto-rotational processes. Here, we report on our three dimensional, adaptive…
We present results of the second phase of our near-ultraviolet investigation into protostellar jet rotation using HST/STIS. We obtain long-slit spectra at the base of five T Tauri jets to determine if there is a difference in radial…
We present fully three-dimensional magnetohydrodynamic jet launching simulations of a jet source orbiting in a binary system. We consider a time-dependent binary gravitational potential, thus all tidal forces that are experienced in the…
Magnetohydrodynamic instabilities can be responsible for the formation of structures with various scales in astrophysical jets. We consider the stability properties of jets containing both the azimuthal and axial field of subthermal…
Context: A large sample of T Tauri stars exhibits optical jets, approximately half of which rotate slowly, only at ten per cent of their breakup velocity. The disk-locking mechanism has been shown to be inefficient to explain this…
We report the discovery of propeller-driven outflows in axisymmetric magnetohydrodynamic simulations of disk accretion to rapidly rotating magnetized stars. Matter outflows in a wide cone and is centrifugally ejected from the inner regions…
We present high angular resolution millimeter wavelength continuum and 13CO(2-1) observations of the circumstellar disk surrounding the TTauri star DG Tauri. We show that the velocity pattern in the inner regions of the disk is consistent…
Motivated by recent subarcsecond resolution observations of jets from T Tauri stars, we extend the work of \citep{Safier93a, Safier93b} by computing the thermal and ionization structure of self-similar, magnetically-driven, atomic disk…
Stars between two and three solar masses rotate rapidly on the main sequence, and their rotation rates in the core helium burning (secondary clump) phase can therefore be used to test models of angular momentum loss used for gyrochronology…
We present Spitzer (IRAC) images observations and a VLT 2.1micron image of the HH 212 outflow. We find that this outflow has a strong symmetry, with jet/counterjet knot pairs with Delta x less than 1 arcsec position offsets. We deduce that…
Numerical simulations of outflows formed during the collapse of 100 M_sun cloud cores are presented. We derive a generalised criterion from MHD wind theory to analyse the launching mechanism of these outflows. The criterion is successfully…
Non-relativistic, magnetically-driven jets are constructed by taking self-consistently into account the feedback on the underlying accretion disc. It is shown that such jets are mostly described by the ejection index $\xi= \mbox{d} \ln \dot…
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…
We consider the conditions under which a rotating magnetic object can produce a magnetically powered outflow in an initially unmagnetized medium stratified under gravity. 3D MHD simulations are presented in which the footpoints of…