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Related papers: Alignment of irregular grains by radiative torques…

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We discuss the modelling of grain boundary dynamics within an amplitude equations description, which is derived from classical density functional theory or the phase field crystal model. The relation between the conditions for periodicity…

A systematic torque from anisotropic radiation can rapidly spin up irregular grains to the point of breakup. We apply the standard theory of rotational disruption from radiative torques to solar system grains, finding that grains with radii…

Earth and Planetary Astrophysics · Physics 2025-03-19 Kedron Silsbee , Brandon S. Hensley , Jamey R. Szalay , Petr Pokorný , Jeong-Gyu Kim

Grain surfaces play a central role in the formation and desorption of molecules in space. To form molecules on a grain surface, adsorbed species trapped in binding sites must be mobile and migrate to adjacent sites. Thermal hopping is a…

Astrophysics of Galaxies · Physics 2019-10-29 Thiem Hoang

One of the most informative techniques of studying magnetic fields in molecular clouds is based on the use of starlight polarization and polarized emission arising from aligned dust. How reliable the interpretation of the polarization maps…

Astrophysics · Physics 2017-01-18 A. Lazarian

Massive stars, supernovae, and kilonovae are among the most luminous radiation sources in the universe. Observations usually show near- to mid-infrared (NIR--MIR, $\lambda\sim 1-5~\mu$m) emission excess from H\,{\sc ii} regions around young…

Astrophysics of Galaxies · Physics 2019-05-09 Thiem Hoang , Le Ngoc Tram , Hyeseung Lee , Sang-Hyeon Ahn

We present a new method for using the observed starlight polarization and polarized submm emission to constrain the shapes and porosities of interstellar grains. We present the modified picket fence approximation (MPFA), and verify that it…

Astrophysics of Galaxies · Physics 2021-10-04 B. T. Draine , Brandon S. Hensley

We study the Poisson Boolean model where the grains are random convex bodies with a rotation-invariant distribution. We say that a grain distribution is dense if the union of the grains covers the entire space and robust if the union of the…

Probability · Mathematics 2024-10-18 Peter Gracar , Marilyn Korfhage , Peter Mörters

A simple model for calculating the diffraction radiation characteristics from an ultrarelativistic charged particle moving close to a tilted ideally conducting strip is developed. Resonant diffraction radiation (RDR) is treated as a…

Accelerator Physics · Physics 2009-10-31 A. P. Potylitsyn , P. V. Karataev , G. A. Naumenko

Odd elasticity describes the unusual elastic response of solids whose stress-strain relationship is not compatible with an elastic potential. Here, we present a study of odd elasticity in a driven granular matter system composed of grains…

Soft Condensed Matter · Physics 2023-12-01 Rosalind Huang , Rituparno Mandal , Colin Scheibner , Vincenzo Vitelli

We propose a set of experiments in which Ramsey-fringe techniques are tailored to probe transitions originating and terminating on the same ground state level. When pulses of resonant radiation, separated by a time delay $% T, $ interact…

Atomic Physics · Physics 2007-05-23 Tycho Sleator , Paul R. Berman , Boris Dubetsky

Shear induced alignment of elongated particles is studied experimentally and numerically. We show that shear alignment of ensembles of macroscopic particles is comparable even on a quantitative level to simple molecular systems, despite the…

Soft Condensed Matter · Physics 2012-04-27 Tamas Borzsonyi , Balazs Szabo , Gabor Toros , Sandra Wegner , Janos Torok , Ellak Somfai , Tomasz Bien , Ralf Stannarius

Grazing-angle scattering (GAS) is a type of Bragg scattering of waves in slanted non-uniform periodic gratings, when the diffracted order satisfying the Bragg condition propagates at a grazing angle with respect to the boundaries of a…

Optics · Physics 2007-05-23 D. K. Gramotnev , T. A. Nieminen

Ratcheting surfaces are a common motif in nature and appear in plant awns and grasses. They are known to profer selective advantages for seed dispersion and burial. In two simple model experiments we show that these anisotropically toothed…

Soft Condensed Matter · Physics 2008-06-25 I. M. Kulić , M. Mani , H. Mohrbach , R. Thaokar , L. Mahadevan

Focussing on preplanetary grains growth, we discuss the properties of dust aggregation driven by magnetic dipole forces. While there is no direct evidence for the existence of magnetic grains present in the solar nebula, there are reasons…

Astrophysics · Physics 2009-11-07 C. Dominik , H. Nuebold

Context. Grains in circumstellar disks are believed to grow by mutual collisions and subsequent sticking due to surface forces. Results of many fields of research involving circumstellar disks, such as radiative transfer calculations, disk…

Earth and Planetary Astrophysics · Physics 2010-09-20 T. Birnstiel , C. W. Ormel , C. P. Dullemond

Interstellar medium is turbulent and this induces relative motions of dust grains. We calculate relative velocities of charged grains in a partially ionized magnetized gas. We account for anisotropy of magnetohydrodynamic (MHD) turbulence,…

Astrophysics · Physics 2009-11-07 A. Lazarian , Huirong Yan

We have computed wind models with time-dependent dust formation and grain-size dependent opacities, where (1) the problem is simplified by assuming a fixed dust-grain size, and where (2) the radiation pressure efficiency is approximated…

Solar and Stellar Astrophysics · Physics 2010-10-04 Lars Mattsson , Susanne Höfner

Discretizations of continuum theories often do not preserve the gauge symmetry content. This occurs in particular for diffeomorphism symmetry in general relativity, which leads to severe difficulties both in canonical and covariant…

General Relativity and Quantum Cosmology · Physics 2011-06-10 Benjamin Bahr , Bianca Dittrich , Song He

Future NASA X-ray Observatories will shed light on a variety of high-energy astrophysical phenomena. Off-plane reflection gratings can be used to provide high throughput and spectral resolution in the 0.3--1.5 keV band, allowing for…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Ryan Allured , Randall L. McEntaffer

The dependence of polarization fraction $p$ on total intensity $I$ in polarized submillimeter emission measurements is typically parameterized as $p\propto I^{-\alpha}$ $(\alpha \leq 1)$, and used to infer dust grain alignment efficiency in…