Related papers: A Magnetically Torqued Disk Model for Be Stars
High-mass stars form in protoclusters, where gravo-magnetic processes shape collapsing clouds and clumps to be elongated preferentially perpendicular to magnetic (B) fields. Yet it remains unclear whether gravo-magnetic processes still…
Theoretical studies of collapsing clouds have found that even a relatively weak magnetic field (B) may prevent the formation of disks and their fragmentation. However, most previous studies have been limited to cases where B and the…
(abridged) As the favoured progenitors of long-duration gamma-ray bursts, massive stars may represent our best signposts of individual objects in the early Universe, but special conditions seem required to make these bursters, which might…
Hot stars are the main source of ionization of the interstellar medium and its enrichment due to heavy elements. Constraining the physical conditions of their environments is crucial to understand how these stars evolve and their impact on…
We study the global bending modes of a thin annular disc subject to both an internally generated magnetic field and a magnetic field due to a dipole embedded in the central star with axis aligned with the disc rotation axis. When there is a…
We have observationally quantified the effect of gravitational torques on stars in disk galaxies due to the stellar distribution itself and explored whether these torques are efficient at transporting angular momentum within a Hubble Time.…
(Abridged) Context. Most massive stars are located in multiple stellar systems. Magnetic fields are believed to be essential in the accretion and ejection processes around single massive protostars. Aims. Our aim is to unveil the influence…
It is widely believed that star clusters form with low star formation efficiencies. With the onset of stellar winds by massive stars or finally when the first super nova blows off, the residual gas is driven out of the embedded star…
Recent observations have suggested that circumstellar disks may commonly form around young stellar objects. Although the formation of circumstellar disks can be a natural result of the conservation of angular momentum in the parent cloud,…
We present a one-dimensional model of the formation and viscous evolution of protoplanetary disks. The formation of the early disk is modeled as the result of the gravitational collapse of an isothermal molecular cloud. The disk's viscous…
We study protoplanetary disc evolution assuming that angular momentum transport is driven by gravitational instability at large radii, and magnetohydrodynamic (MHD) turbulence in the hot inner regions. At radii of the order of 1 AU such…
Gravitational coupling between planets and protoplanetary discs is responsible for many important phenomena such as planet migration and gap formation. The key quantitative characteristics of this coupling is the excitation torque density…
Protoplanetary disks are quasi-steady structures whose evolution and dispersal determine the environment for planet formation. I review the theory of protoplanetary disk evolution and its connection to observations. Substantial progress has…
The accretion disk around a rotating magnetic star (neutron star, white dwarf or T Tauri star) is subjected to periodic vertical magnetic forces from the star, with the forcing frequency equal to the stellar spin frequency or twice the spin…
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…
The space velocities and Galactic orbital elements of stars calculated from the currently available high-accuracy observations in our summary catalog of spectroscopic magnesium abundances in dwarfs and subgiants in the solar neighborhood…
(Abridged version) We present the first detailed imaging polarization observations of six SMC and six LMC clusters, known to have large populations of B-type stars which exhibit excess H-alpha emission, to constrain the evolutionary status…
This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star.…
The conventional accretion disk lore is that magnetized turbulence is the principal angular momentum transport process that drives accretion. However, when dynamically important large-scale magnetic fields thread an accretion disk, they can…
In star formation, magnetic fields act as a cosmic angular momentum extractor that increases mass accretion rates onto protostars and in the process, creates spectacular outflows. However, recently it has been argued that this magnetic…