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Spiral structure in disk galaxies is modeled with nine collisionless N-body simulations including live disks, halos, and bulges with a range of masses. Two of these simulations make long-lasting and strong two-arm spiral wave modes that…

Astrophysics of Galaxies · Physics 2016-08-03 Kanak Saha , Bruce Elmegreen

We analyse, using new analytical models and numerical general relativistic magnetohydrodynamic simulations, the three-dimensional properties of accretion flows inside the plunging region of black hole spacetimes (i.e., at radii smaller than…

High Energy Astrophysical Phenomena · Physics 2024-07-03 Andrew Mummery , James M. Stone

Late-stage infall onto evolved protoplanetary discs is an important source of material and angular momentum replenishment, and disc substructures. In this paper we used 3D smoothed particle hydrodynamics simulations to model streamer-disc…

Earth and Planetary Astrophysics · Physics 2025-02-12 Josh Calcino , Daniel J. Price , Thomas Hilder , Valentin Christiaens , Jessica Speedie , Chris W. Ormel

I review theoretical aspects of the interaction between the accretion stream and the disk in interacting binary systems, concentrating on recent hydrodynamic calculations. At low accretion rates, cooling is expected to be efficient, and the…

Astrophysics · Physics 2007-05-23 Philip J. Armitage

Pebble accretion offers an efficient pathway to form planets, driven by a constant supply of inward drifting mass and an accretion efficiency enhanced by gas drag. While most studies assume a single pebble size (monodisperse), real discs…

Earth and Planetary Astrophysics · Physics 2026-04-29 T. J. Konijn , S. -J. Paardekooper

A large fraction of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question if and how planets in binary systems may form. Protoplanetary disks are the…

AxFe2-ySe2 (A=K, Rb, Cs) superconductors may show a complex mixture of structural phases even in a single crystal form. A full sphere of the diffraction intensity has been collected, with the help of synchrotron radiation, for Cs0.8Fe1.6Se2…

We have performed Smoothed Particle Hydrodynamics (SPH) simulations to study the time evolution of one and two protoplanets embedded in a protoplanetary accretion disc. We investigate accretion and migration rates of a single protoplanet…

Astrophysics · Physics 2009-11-10 C. Schaefer , R. Speith , M. Hipp , W. Kley

We present a unified theory of linear spiral structure in stellar disks. We begin by identifying the characteristic scales involved in the spiral structure problem and listing some quantitative requirements of a successful theory. We then…

Astrophysics of Galaxies · Physics 2025-07-24 Chris Hamilton , Shaunak Modak , Scott Tremaine

We present the computed phase diagram of columnar structures of soft spheres under pressure, of which the main feature is the appearance and disappearance of line slips, the shearing of adjacent spirals, as pressure is increased. A…

Soft Condensed Matter · Physics 2019-02-27 Jens Winkelmann , Benjamin Haffner , Denis Weaire , Adil Mughal , Stefan Hutzler

We discuss the ability of the smoothed particle hydrodynamics (SPH) method combined with a grid-based solver for the Poisson equation to model mass accretion onto protostars in gravitationally unstable protostellar discs. We scrutinize…

Earth and Planetary Astrophysics · Physics 2018-09-06 Olga P. Stoyanovskaya , Nikolay V. Snytnikov , Valeriy N. Snytnikov

Disordered systems like liquids, gels, glasses, or granular materials are not only ubiquitous in daily life and in industrial applications but they are also crucial for the mechanical stability of cells or the transport of chemical and…

Disordered Systems and Neural Networks · Physics 2020-07-06 Zhen Zhang , Walter Kob

Spiral density waves are thought to be excited in the accretion discs of accreting compact objects, including Cataclysmic Variable stars (CVs). Observational evidence has been obtained for a handful of systems in outburst over the last two…

High Energy Astrophysical Phenomena · Physics 2019-11-06 R. Ruiz-Carmona , P. J. Groot , D. T. H. Steeghs

Remarkably persistent mixing and non-mixing regions (islands) are observed to coexist in a three-dimensional dynamical system where randomness is expected. The track of an x-ray opaque particle in a spherical shell half-filled with dry…

Soft Condensed Matter · Physics 2018-09-05 Zafir Zaman , Mengqi Yu , Paul P. Park , Julio M. Ottino , Richard M. Lueptow , Paul B. Umbanhowar

A fundamental difficulty of studying gas-liquid pipe flows is the prediction of the occurrence and characteristics of the slug flow regime, which plays a crucial role in the safety design of oil pipelines. Current empirical methods and…

Fluid Dynamics · Physics 2024-05-24 Massoud Rezavand , Xiangyu Hu

We present K'(2.1 micron) observations of four nearby flocculent spirals, which clearly show low-level spiral structure and suggest that kiloparsec-scale spiral structure is more prevalent in flocculent spirals than previously supposed. In…

Astrophysics · Physics 2009-10-28 Michele D. Thornley

We have obtained Integral Field Spectroscopy for 23 spiral bulges using INTEGRAL on the William Herschel Telescope and SPIRAL on the Anglo-Australian Telescope. This is the first 2D survey directed solely at the bulges of spiral galaxies.…

We study the vertical perturbations in the galactic disc of the Milky Way-size high-resolution hydrodynamical cosmological simulation named GARROTXA. We detect phase spirals in the vertical projection $Z- V_{Z}$ of disc's stellar particles…

Astrophysics of Galaxies · Physics 2022-06-24 Begoña García-Conde , Santi Roca-Fàbrega , Teresa Antoja , Pau Ramos , Octavio Valenzuela

Class II protoplanetary discs feature numerous non-axisymmetric substructures like spirals and the underlying mechanisms for their formation are still highly debated. Coincidentally, early stage, massive discs are subject to the…

Solar and Stellar Astrophysics · Physics 2026-03-25 Marc Van den Bossche , Oliver Gressel

The structure and properties of water or ice are of great interest to researchers due to their importance in the biological, cryopreservation and environmental fields. Hexagonal ice (Ih) is a common ice phase in nature and has been…