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We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized…

Earth and Planetary Astrophysics · Physics 2015-05-27 S. Hirose , N. J. Turner

This chapter presents controlled approximations of Kohn-Sham density functional theory (DFT) that enable very large scale simulations. The work is motivated by the study of defects in crystalline solids, though the ideas can be used in…

Materials Science · Physics 2021-12-14 Kaushik Bhattacharya , Vikram Gavini , Michael Ortiz , Mauricio Ponga , Phanish Suryanarayana

Recently, Lanzetta et al. (2002) have measured the distribution of star formation rate intensity in galaxies at various redshifts. This data set has a number of advantages relative to galaxy luminosity functions; the effect of…

Astrophysics · Physics 2015-06-24 Rennan Barkana

A new formalism is presented for finding equilibrium distribution functions for axisymmetric systems. The formalism, obtainded by using the concept of fractional derivatives, generalizes the methods of Fricke (1952), Kalnajs (1972) and…

Astrophysics · Physics 2009-06-14 Juan F. Pedraza , Javier Ramos-Caro , Guillermo A. Gonzalez

Unraveling the nature of dark matter (DM) stands as a primary objective in modern physics. Here we present evidence suggesting deviations from the collisionless Cold DM (CDM) paradigm. It arises from the radial distribution of stars in six…

Astrophysics of Galaxies · Physics 2024-07-25 Jorge Sanchez Almeida , Ignacio Trujillo , Angel R. Plastino

The mass distributions of dense cores in star-forming regions are measured to have a shape similar to the initial mass function of stars. This has been generally interpreted to mean that the constituent cores will form individual stars or…

Astrophysics · Physics 2009-11-13 Jonathan J. Swift , Jonathan P. Williams

The triangle distribution function f^(3) for three mutual nearest neighbors in the plane describes basic aspects of short-range order and statistical thermodynamics in two-dimensional many-particle systems. This paper examines prospects for…

Using high-resolution N-body simulations we study the stellar properties of dwarf spheroidal galaxies resulting from the tidally induced morphological transformation of disky dwarfs on a cosmologically motivated eccentric orbit around the…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-15 Ewa L. Lokas , Stelios Kazantzidis , Jaroslaw Klimentowski , Lucio Mayer , Simone Callegari

Computations in high-dimensional spaces can often be realized only approximately, using a certain number of projections onto lower dimensional subspaces or sampling from distributions. In this paper, we are interested in pairs of…

Numerical Analysis · Mathematics 2025-02-26 Nicolaj Rux , Michael Quellmalz , Gabriele Steidl

We investigate the spatiotemporal structure of simulations of the homogeneous slab and isothermal plane models for the vertical motion in the Galactic disc. We use Dynamic Mode Decomposition (DMD) to compute eigenfunctions of the simulated…

Astrophysics of Galaxies · Physics 2019-09-17 Keir Darling , Lawrence M. Widrow

We investigate how significant the spiral structure is on calculations concerning radiative transfer in dusty spiral galaxies seen edge-on. The widely adopted exponential disk model (i.e. both the stars and the dust are distributed…

Astrophysics · Physics 2007-05-23 A. Misiriotis , N. D. Kylafis , J. Papamastorakis , E. M. Xilouris

Thermodynamics play an important role in determining the way a protostellar disc fragments to form planets, brown dwarfs and low-mass stars. We explore the effect that different treatments of radiative transfer have in simulations of…

Astrophysics of Galaxies · Physics 2015-05-13 Dimitris Stamatellos , Anthony Whitworth

This paper investigates probability density functions (PDFs) that are continuous everywhere, nearly uniform around the mode of distribution, and adaptable to a variety of distribution shapes ranging from bell-shaped to rectangular. From the…

Machine Learning · Computer Science 2022-04-01 Osamu Fujita

Dynamical models are used to study dark matter (DM) in galaxies, how galaxies assemble through mergers, and to test galaxy formation models. Despite its widespread use, there has been no systematic study quantifying how much information can…

Astrophysics of Galaxies · Physics 2025-11-14 Paula Gherghinescu , Eugene Vasiliev , Payel Das , Justin Read

A phase-space distribution function of the steady state in galaxy models that admits regular orbits overall in the phase-space can be represented by a function of three action variables. This type of distribution function in Galactic models…

Astrophysics of Galaxies · Physics 2015-06-19 Haruhiko Ueda , Takuji Hara , Naoteru Gouda , Taihei Yano

Photoevaporation by stellar ionizing radiation is believed to play an important role in the dispersal of disks around young stars. The mass loss model for dust-free disks developed by Hollenbach et al. is currently regarded as a…

Solar and Stellar Astrophysics · Physics 2015-06-16 Kei E. I. Tanaka , Taishi Nakamoto , Kazuyuki Omukai

We present a method for fitting orbit-superposition models to the kinematics of discrete stellar systems when the available stellar sample has been filtered by a known selection function. The fitting method can be applied to any model in…

Astrophysics of Galaxies · Physics 2019-01-23 John Magorrian

Fractional calculus allows one to generalize the linear, one-dimensional, diffusion equation by replacing either the first time derivative or the second space derivative by a derivative of fractional order. The fundamental solutions of…

Statistical Mechanics · Physics 2007-05-23 Francesco Mainardi , Paolo Paradisi , Rudolf Gorenflo

We use high-quality optical rotation curves of 9 low-luminosity disk galaxies to obtain the velocity profile of the surrounding dark matter halos. We find that they increase linearly with radius at least out to the stellar disk edge,…

Astrophysics · Physics 2009-10-31 A. Borriello , P. Salucci

Recent theoretical work suggests that it may be common for stars in the disks of spiral galaxies to migrate radially across significant distances in the disk. Such migrations are a result of resonant scattering with spiral arms and move the…

Astrophysics of Galaxies · Physics 2015-03-17 R. Roškar , V. P. Debattista , S. R. Loebman , Ž. Ivezić , T. R. Quinn