Zobrazeno 1 - 10
of 220
pro vyhledávání: '"Marchand, Pierre"'
Many mechanisms have been proposed to alleviate the magnetic catastrophe, which prevents the Keplerian disk from forming inside a collapsing magnetized core. Such propositions include inclined field and non-ideal magnetohydrodynamics effects, and hav
Externí odkaz:
http://arxiv.org/abs/2401.02845
Publikováno v:
A&A 670, A61 (2023)
Dust grains influence many aspects of star formation, including planet formation, opacities for radiative transfer, chemistry, and the magnetic field via Ohmic, Hall, and ambipolar diffusion. The size distribution of the dust grains is the primary ch
Externí odkaz:
http://arxiv.org/abs/2301.01510
We model the coagulation and fragmentation of dust grains during the protostellar collapse with our newly developed shark code. It solves the gas-dust hydrodynamics in a spherical geometry and the coagulation/fragmentation equation. It also computes
Externí odkaz:
http://arxiv.org/abs/2211.01891
The scattering phase, defined as $ \log \det S ( \lambda ) / 2\pi i $ where $ S ( \lambda ) $ is the (unitary) scattering matrix, is the analogue of the counting function for eigenvalues when dealing with exterior domains and is closely related to Kr
Externí odkaz:
http://arxiv.org/abs/2210.09908
Publikováno v:
A&A 666, A27 (2022)
Thermal ionization is a critical process at temperatures T > 10 3 K, particularly during star formation. An increase in ionization leads to a decrease in nonideal magnetohydrodynamics (MHD) resistivities, which has a significant impact on protoplanet
Externí odkaz:
http://arxiv.org/abs/2202.11625
We study a commonly-used second-kind boundary-integral equation for solving the Helmholtz exterior Neumann problem at high frequency, where, writing $\Gamma$ for the boundary of the obstacle, the relevant integral operators map $L^2(\Gamma)$ to itsel
Externí odkaz:
http://arxiv.org/abs/2109.06017
The role of non-ideal magnetohydrodynamics has been proven critical during the formation of the protoplanetary disk, particularly in regulating its size. We provide a simple model to predict the disk size under the interplay among the ambipolar diffu
Externí odkaz:
http://arxiv.org/abs/2109.05823
Publikováno v:
A&A 649, A50 (2021)
Dust grains play a major role in many astrophysical contexts. They affect the chemical, magnetic, dynamical, and optical properties of their environment, from galaxies down to the interstellar medium, star-forming regions, and protoplanetary disks. T
Externí odkaz:
http://arxiv.org/abs/2103.00002
We consider GMRES applied to discretisations of the high-frequency Helmholtz equation with strong trapping; recall that in this situation the problem is exponentially ill-conditioned through an increasing sequence of frequencies. Under certain assump
Externí odkaz:
http://arxiv.org/abs/2102.05367
For the Helmholtz equation posed in the exterior of a Dirichlet obstacle, we prove that if there exists a family of quasimodes (as is the case when the exterior of the obstacle has stable trapped rays), then there exist near-zero eigenvalues of the s
Externí odkaz:
http://arxiv.org/abs/2101.02116