Related papers: Consistency of Ambipolar Diffusion Models with Inf…
We have mapped linearly polarized dust emission from L183 with the JCMT SCUBA polarimeter and have analyzed these and our previously published data for the prestellar cores L183, L1544, and L43 in order to estimate magnetic field strengths…
We propose an analytical model for the quasistatic evolution of starless cores confined by a constant external pressure, assuming that cores are isothermal and obey a spherically-symmetric density distribution. We model core evolution for…
Large field surveys of NH3, C2S, 13CO and C18O in the L1551 dark cloud have revealed a prolate, pre-protostellar molecular core (L1551-MC) in a relatively quiescent region to the northwest of the well-known IRS 5 source. The kinetic…
The increased sensitivity and spectral resolution of observed spectra towards the pre-stellar core L1544 are challenging the current physical and chemical models. With the aim of further constraining the structure of L1544 as well as…
This paper explores the sensitivity of line profiles of H2D+, HCO+ and N2H+, observed towards the center of L1544, to various kinematic and chemical parameters. The total width of the H2D+ line can be matched by a static model and by models…
We develop a self-consistent model for the equilibrium gas temperature and size-dependent dust temperature in cold, dense pre-stellar cores, assuming an arbitrary power-law size distribution of dust grains. Compact analytical expressions…
Starless dense cores eventually collapse dynamically, which forms protostars inside them, and the physical properties of the cores determine the nature of the forming protostars. We report ALMA observations of dust continuum emission and…
Disks are essential to the formation of both stars and planets, but how they form in magnetized molecular cloud cores remains debated. This work focuses on how the disk formation is affected by turbulence and ambipolar diffusion (AD), both…
Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…
Isolated low-mass stars are formed in dense cores of molecular clouds. In the standard picture, the cores are envisioned to condense out of strongly magnetized clouds through ambipolar diffusion. Most previous calculations based on this…
Magnetic flux redistribution lies at the heart of the problem of star formation in dense cores of molecular clouds that are magnetized to a realistic level. If all of the magnetic flux of a typical core were to be dragged into the central…
The distribution of protostar masses is studied for core-environment systems whose duration of infall follows a waiting-time distribution. Each core-environment system has a continuous density profile with no barrier to mass flow. The core…
The ambipolar-diffusion theory of star formation predicts the formation of fragments in molecular clouds with mass-to-flux ratios greater than that of the parent-cloud envelope. By contrast, scenarios of turbulence-induced fragmentation do…
We analyze the properties of steady and time-dependent C shocks under conditions prevailing in giant molecular clouds. For steady C shocks, we show that ionization equilibrium holds and use numerical integrations to obtain the shock…
We present a solution for the observed core fragmentation of filaments in the Taurus L1517 dark cloud which previously could not be explained (Hacar et. al 2011). Core fragmentation is a vital step for the formation of stars. Observations…
In the centre of pre-stellar cores, deuterium fractionation is enhanced due to the low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to study the earliest stages of star formation. We analyse…
The collapse and fragmentation of initially prolate and oblate, magnetic molecular clouds is calculated in three dimensions with a gravitational, radiative hydrodynamics code. The code includes magnetic field effects in an approximate…
We present a parameter study of simulations of fragmentation regulated by gravity, magnetic fields, ambipolar diffusion, and nonlinear flows. The thin-sheet approximation is employed with periodic lateral boundary conditions, and the…
The physical conditions in a collapsing cloud can be traced by observations of molecular lines. To correctly interpret these observations the abundance distributions of the observed species need to be derived. The chemistry in a collapsing…
(Abridged) Context. Massive stars form in magnetized and turbulent environments, and are often located in stellar clusters. Their accretion mechanism, as well as the origin of their system's stellar multiplicity are poorly understood. Aims.…