Related papers: Spin-down of solar-mass protostars in magnetospher…
The early pre-main sequence phase during which they are still likely surrounded by an accretion disk represents a puzzling stage of the rotational evolution of solar-mass stars. While they are still accreting and contracting they do not…
We present a model for the rotational evolution of a young, solar-mass star interacting magnetically with an accretion disk. As in a previous paper (Paper I), the model includes changes in the star's mass and radius as it descends the…
[Abridged] In order to explain the slow rotation observed in a large fraction of accreting pre-main-sequence stars (CTTSs), we explore the role of stellar winds in torquing down the stars. For this mechanism to be effective, the stellar…
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 propeller regime of disk accretion to a rapidly rotating magnetized star is investigated here for the first time by axisymmetric 2.5D magnetohydrodynamic simulations. An expanded, closed magnetosphere forms in which the magnetic field…
The interaction between a protostellar magnetosphere and a surrounding dynamo-active accretion disc is investigated using an axisymmetric mean-field model. In all models investigated, the dynamo-generated magnetic field in the disc arranges…
We formulate a general, steady-state model for the torque on a magnetized star from a surrounding accretion disc. For the first time, we include the opening of dipolar magnetic field lines due to the differential rotation between the star…
We review the theoretical efforts to understand why pre-main-sequence stars spin much more slowly than expected. The first idea put forward was that massive stellar winds may remove substantial angular momentum. Since then, it has become…
We examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD…
This paper examines the outflows associated with the interaction of a stellar magnetosphere with an accretion disk. In particular, we investigate the magnetospheric ejections (MEs) due to the expansion and reconnection of the field lines…
When they first appear in the HR diagram, young stars rotate at a mere 10\% of their break-up velocity. They must have lost most of the angular momentum initially contained in the parental cloud, the so-called angular momentum problem. We…
We compare the stellar wind torque calculated in a previous work (Paper II) to the spin-up and spin-down torques expected to arise from the magnetic interaction between a slowly rotating ($\sim 10$% of breakup) pre-main-sequence star and…
Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can…
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…
While magnetic fields have long been considered to be important for the evolution of magnetic non-degenerate stars and compact stars, it has become clear in recent years that actually all of the stars are deeply affected. This is…
We develop new angular momentum evolution models for stars with masses of $0.5$ to $1.6~\rm M_\odot$ and from the pre-main-sequence (\rm PMS) through the end of their main-sequence (\rm MS) lifetime. The parametric models include magnetic…
Stellar winds are believed to be the dominant factor in spin down of stars over time. However, stellar winds of solar analogs are poorly constrained due to the challenges in observing them. A great improvement has been made in the last…
The spin evolution of main sequence stars has long been of interest for basic stellar evolution, stellar aging, stellar activity, and consequent influence on companion planets. Observations of older than solar late-type main-sequence stars…
Magnetic interactions between a protostar and its accretion disc tend to induce warping in the disc and produce secular changes in the stellar spin direction, so that the spin axis may not always be perpendicular to the disc. This may help…
A new type of wind - a conical wind - has been discovered in axisymmetric magnetohydrodynamic simulations of the disk-magnetosphere interaction in cases where the magnetic field of the star is bunched into an X-type configuration. Such a…