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A parametric model of granulation employing a small number of parameters was developed. Synthetic spectra calculated using this model closely match observed spectra and, in particular, reproduce the asymmetries observed in spectral lines.…

Solar and Stellar Astrophysics · Physics 2017-08-23 Timo A. Nieminen

The outer surface layers of the sun show a clear deceleration at low latitudes. This is generally thought to be the result of a strong dominance of vertical turbulent motions associated with strong downdrafts. This strong negative radial…

Astrophysics · Physics 2009-11-13 Axel Brandenburg

We present a detailed comparison between the photometric properties of the bulges of two simulated galaxies and those of a uniform sample of observed galaxies. This analysis shows that the simulated galaxies have bulges with realistic…

Astrophysics of Galaxies · Physics 2014-06-19 C. R. Christensen , A. M. Brooks , D. B. Fisher , F. Governato , J. McCleary , T. R. Quinn , S. Shen , J. Wadsley

The transport of sediments by a fluid flow is commonly found in nature and in industry. In nature, it is found in rivers, oceans, deserts, and other environments. In industry, it is found in petroleum pipelines conveying grains, in sewer…

Fluid Dynamics · Physics 2016-08-17 Marcos Roberto Mendes Penteado , Erick de Moraes Franklin

We use high spatial resolution observations and numerical simulations to study the velocity distribution of solar photospheric magnetic bright points. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere…

Flows on the solar surface are linked to solar activity, and LCT is one of the standard techniques for capturing the dynamics of these processes by cross-correlating solar images. However, the link between contrast variations in successive…

Solar and Stellar Astrophysics · Physics 2015-06-16 M. Verma , M. Steffen , C. Denker

We employ time sequences of images observed with a G-band filter (4305{\AA}) by the Solar Optical Telescope (SOT) on board of Hinode spacecraft at different latitude along solar central me-ridian to study vorticity of granular flows in…

Solar and Stellar Astrophysics · Physics 2017-02-02 A. A. Pevtsov

We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere. A highly efficient feature-tracking technique…

Solar and Stellar Astrophysics · Physics 2016-11-25 H. Tian , H. E. Potts , E. Marsch , R. Attie , J. -S. He

Galaxy cluster peculiar velocities can be inferred from high-sensitivity, high-resolution multiple-frequency observations in the 30 to 400 GHz range. While galaxy cluster counts and power spectra are sensitive to the growth factor, peculiar…

Astrophysics · Physics 2009-11-07 A. Peel , L. Knox

Although the solar wind flows primarily outward from the Sun to interplanetary space, there are times when small-scale plasma inflows are observed. Inward-propagating density fluctuations in polar coronal holes were detected by the COR2…

Solar and Stellar Astrophysics · Physics 2021-05-26 Steven R. Cranmer , Craig E. DeForest , Sarah E. Gibson

The measurement of Doppler velocities in spectroscopic solar observations requires a reference for the local frame of rest. The rotational and radial velocities of the Earth and the rotation of the Sun introduce velocity offsets in the…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jaime de la Cruz Rodríguez , Dan Kiselman , Mats Carlsson

Several lines of evidence suggest that the velocity amplitude in global simulations of solar convection, U, may be systematically over-estimated. Motivated by these recent results, we explore the factors that determine U and we consider how…

Solar and Stellar Astrophysics · Physics 2016-09-21 Bridget O'Mara , Mark S. Miesch , Nicholas A. Featherstone , K. C. Augustson

We present large-scale molecular dynamics simulations to study the free evolution of granular gases. Initially, the density of particles is homogeneous and the velocity follows a Maxwell-Boltzmann (MB) distribution. The system cools down…

Statistical Mechanics · Physics 2016-09-21 Prasenjit Das , Sanjay Puri , Moshe Schwartz

New data on the membership of the Local Group, in conjunction with new and improved radial velocity data, are used to refine the derivation of the motion of the Sun relative to the Local Group (hereafter LG). The Sun is found to be moving…

Astrophysics · Physics 2009-10-31 Stephane Courteau , Sidney van den Bergh

As large--distance rays (say, 10\,-\,$24 ^\circ$) approach the solar surface approximately vertically, travel times measured from surface pairs for these large separations are mostly sensitive to vertical flows, at least for shallow flows…

Solar and Stellar Astrophysics · Physics 2015-06-05 Thomas L. Duvall, , Shravan M. Hanasoge

Spatially-resolved X-ray observations are the key to understanding electron acceleration in solar flares. Currently, the underlying processes that efficiently energize solar flare particles are poorly constrained. Abundant flare…

Solar and Stellar Astrophysics · Physics 2026-03-09 Morgan Stores , Natasha Jeffrey , Ewan Dickson , James McLaughlin , Eduard Kontar

In the solar neighbourhood, there are moving groups of stars with similar ages and others of stars with heterogeneous ages as the field stars. To explain these facts, we have constructed a simple model of three phases. Phase A: a giant…

Astrophysics of Galaxies · Physics 2015-02-11 Carlos A. Olano

This paper describes a series of 3D simulations of shallow inefficient convection in the outer layers of the Sun. The computational domain is a closed box containing the convection-radiation transition layer, located at the top of the solar…

Astrophysics · Physics 2009-11-07 F. J. Robinson , P. Demarque , L. H. Li , S. Sofia , Y. -C. Kim , K. L. Chan , D. B. Guenther

We derive formulae connecting the frequency variations in the spectrum of solar oscillations to the dynamical quantities that are expected to change over the solar activity cycle. This is done for both centroids and the asymmetric part of…

Astrophysics · Physics 2009-11-10 W. A. Dziembowski , P. R. Goode

The rotation of granules shows thermal properties similar to the thermal motion of molecules, which effects convection criterion and solar granule size.The granular rotation generates the rotational additional pressure and corresponding…

Solar and Stellar Astrophysics · Physics 2023-04-07 Haibin Chen , Rong Wu