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In protoplanetary discs and planetary atmospheres, dust grains coagulate to form fractal dust aggregates. The geometric cross-section of these aggregates is a crucial parameter characterizing aerodynamical friction, collision rates, and…

Earth and Planetary Astrophysics · Physics 2021-04-28 Ryo Tazaki

Simulations of massive star formation predict the formation of discs with significant substructure, such as spiral arms and clumps due to fragmentation. Here we present a semi-analytic framework for producing synthetic observations of discs…

The Search for Planets Orbiting Two Stars (SPOTS) survey aims to study the formation and distribution of planets in binary systems by detecting and characterizing circumbinary planets and their formation environments through direct imaging.…

As recent observations of the molecular discs in spiral galaxies point to the existence of a diffuse, low-density thick molecular disc along with the prominent thin one, we investigate the observational signatures of this thick disc by…

Astrophysics of Galaxies · Physics 2020-07-08 Narendra Nath Patra

This article discusses the construction of dual frames and their uniqueness for the multiplication generated frames on $L^2(X; \mathcal H)$, where $X$ is a $\sigma$-finite measure. A necessary and sufficient condition of such duals…

Functional Analysis · Mathematics 2023-01-19 Sudipta Sarkar , Niraj K. Shukla

We calculate the energy level statistics in a two-dimensional disc with diffusive boundary scattering by the means of the recently proposed ballistic nonlinear sigma-model.

Mesoscale and Nanoscale Physics · Physics 2007-05-23 V. Tripathi , D. E. Khmelnitskii

In a disc galaxy the distribution of azimuthal components of velocity is very skew. In the past this skewness has been modelled by superposed Gaussians. We use dynamical arguments to derive an analytic formula that can be fitted to observed…

Astrophysics of Galaxies · Physics 2015-05-30 Ralph Schoenrich , James Binney

Angle halving, or alternatively the reverse operation of angle doubling, is a useful tool when studying directional distributions. It is especially useful on the circle where, in particular, it yields an identification between the wrapped…

Statistics Theory · Mathematics 2022-02-25 John T. Kent

A method for estimating the axis of reflectional symmetry of an image $f(x,y)$ on the unit disc $D=\{(x,y):x^2+y^2\leq1\}$ is proposed, given that noisy data of $f(x,y)$ are observed on a discrete grid of edge width $\Delta$. Our estimation…

Applications · Statistics 2011-02-04 Nicolai Bissantz , Hajo Holzmann , Mirosław Pawlak

We present a statistical characterization of circumstellar disk orientations toward 12 protostellar multiple systems in the Perseus molecular cloud using the Atacama Large Millimeter/submillimeter Array at Band 6 (1.3 mm) with a resolution…

Structure and spectral energy distributions (SEDs) of externally irradiated circumstellar disks are often computed on the basis of the two-temperature model of Chiang & Goldreich. We refine these calculations by using a more realistic…

Astrophysics · Physics 2009-11-11 Roman R. Rafikov , Fabio De Colle

The on-axis cross-spectral density (CSD) of a beam radiated by a stationary source with a circular coherence state and a Gaussian spectral density is obtained in the closed form. It is revealed that the on-axis CSD is expressed via the…

In this paper, we consider a simple kinematic model, which is a rotating disc on the edge of another fixed disc without slipping, and study the rotation angle of the rotating disc. The rotation angle consists of two parts, the dynamical…

Mathematical Physics · Physics 2025-06-11 Takuya Matsumoto , Hiroki Takada , Osami Yasukura

We present an extended scheme for the calculation of the profiles of emission lines from accretion discs around rotating black holes. The scheme includes discs with angular momenta which are parallel and antiparallel with respect to the…

High Energy Astrophysical Phenomena · Physics 2015-05-19 T. Dauser , J. Wilms , C. S. Reynolds , L. W. Brenneman

Here we present a comprehensive derivation of the analytical expression for the spatiotemporal acoustic pressure generated by photoacoustic sources with spherically symmetric initial pressure distributions. Starting from the fundamental…

Optics · Physics 2026-03-02 Shuang Li , Yibing Wang , Yu Zhang , Changhui Li

We have measured the absolute doubly differential angular sputtering yield for 20 keV Kr+ impacting a polycrystalline Cu slab at an incidence angle of {\theta}i = 45{\deg} relative to the surface normal. Sputtered Cu atoms were captured…

By a computer simulation approach we study the scattering of $p$- or $s$-polarized light from a two-dimensional, randomly rough, perfectly conducting surface. The pair of coupled inhomogeneous integral equations for two independent…

Optics · Physics 2010-05-04 Ingve Simonsen , Alexei A. Maradudin , Tamara A. Leskova

We study a system of equal-sized circular discs each with an asymmetrically placed pivot at a fixed distance from the center. The pivots are fixed at the vertices of a regular triangular lattice. The discs can rotate freely about the…

Statistical Mechanics · Physics 2023-10-19 Sushant Saryal , Deepak Dhar

The article considers the optically thick accretion discs with the progressive increasing height. The surface is assumed to be the conical form. The radiation with considered wavelength emerges from an ring on the cone and is described by…

Solar and Stellar Astrophysics · Physics 2019-07-16 N. A. Silant'ev , G. A. Alekseeva , V. V. Novikov

A concise derivation of the "Joel equations", which allow for the determination of the axis angle 2V from measurements of extinction directions on a spindle stage, is provided starting from the wave-equation. Only analytic methods and no…

Computational Physics · Physics 2017-03-02 Florian Dufey