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Related papers: Helioseismic tests of diffusion theory

200 papers

We present calculations of helicity based on our solar dynamo model and show that the results are consistent with observational data.

Astrophysics · Physics 2009-11-10 Arnab Rai Choudhuri , Piyali Chatterjee , Dibyendu Nandy

A grid of numerical simulations of double-diffusive convection is presented for the astrophysical case where viscosity (Prandtl number Pr) and solute diffusivity (Lewis number Le) are much smaller than the thermal diffusivity. As in…

Solar and Stellar Astrophysics · Physics 2015-06-15 F. Zaussinger , H. Spruit

Mixing a passive scalar field by stirring can be measured in a variety of ways including tracer particle dispersion, via the flux-gradient relationship, or by suppression of scalar concentration variations in the presence of inhomogeneous…

Fluid Dynamics · Physics 2010-11-08 Zhi Lin , Katarína Bodová , Charles R. Doering

Helical distributed chaos in magnetic field has been studied using results of direct numerical simulations (dominated by magnetic helicity), of a laboratory experiment with plasma wind tunnel and of solar wind measurements (dominated by…

Space Physics · Physics 2019-07-11 A. Bershadskii

It is well known that the observed amplitude of solar oscillations is lower in sunspots than in quiet regions of the Sun. We show that this local reduction in oscillation amplitudes combined with the phase-speed filtering procedure in…

Astrophysics · Physics 2009-11-11 S. P. Rajaguru , A. C. Birch , T. L. Duvall , M. J. Thompson , J. Zhao

Reducing theoretical uncertainties in Galactic dark matter (DM) searches is an important challenge as several experiments are now delving into the parameter space relevant to popular (particle or not) candidates. Since many DM signal…

Astrophysics of Galaxies · Physics 2020-10-20 Thomas Lacroix , Arturo Núñez-Castiñeyra , Martin Stref , Julien Lavalle , Emmanuel Nezri

The transport of energetic particles in response to solar wind turbulence is important for space weather. To understand charged particle transport, it is usually assumed that the phase of the turbulence is randomly distributed (the random…

Space Physics · Physics 2023-05-09 Masaru Nakanotani , Lingling Zhao , Gary P. Zank

Linear time-distance helioseismic inversions are carried out using several filtering schemes to determine vector flow velocities within two $\sim100^2\,{\rm Mm^2}\times 20\,{\rm Mm}$ realistic magnetohydrodynamic sunspot simulations of…

Solar and Stellar Astrophysics · Physics 2015-06-22 K. DeGrave , J. Jackiewicz , M. Rempel

We approximate a diffusion equation with highly oscillatory coefficients with a diffusion equation with constant coefficients. The approach is put in action in contexts where only partial information (namely the global energy stored in the…

Optimization and Control · Mathematics 2026-02-17 Claude Le Bris , Frédéric Legoll , Simon Ruget

The heliosphere serves as a probe of interstellar material (ISM) close to the Sun. Measurements of ISM inside and outside of the heliosphere show that we reside in typical warm partially ionized ISM that can be successfully modeled using…

Astrophysics · Physics 2007-05-23 P. C. Frisch

Earth System Models (ESMs) are essential for understanding the interaction between human activities and the Earth's climate. However, the computational demands of ESMs often limit the number of simulations that can be run, hindering the…

Atmospheric and Oceanic Physics · Physics 2024-09-19 Seth Bassetti , Brian Hutchinson , Claudia Tebaldi , Ben Kravitz

We examine the constraints imposed by helioseismic data on the solar heavy element abundances. In prior work we argued that the measured depth of the surface convection zone R_CZ and the surface helium abundance Y_surf were good metallicity…

Solar and Stellar Astrophysics · Physics 2010-05-05 F. Delahaye , M. H. Pinsonneault , L. Pinsonneault , C. J. Zeippen

We extend an existing Born approximation method for calculating the linear sensitivity of helioseismic travel times to flows from Cartesian to spherical geometry. This development is necessary for using the Born approximation for inferring…

Solar and Stellar Astrophysics · Physics 2016-06-15 Vincent G. A. Böning , Markus Roth , Wolfgang Zima , Aaron C. Birch , Laurent Gizon

We apply computational seismic holography to high-frequency helioseismic observations of the quiet Sun from SDO/HMI to locate predominant sources of seismic emission with respect to the structure of the solar granulation. The regions of…

Solar and Stellar Astrophysics · Physics 2013-07-05 Charles Lindsey , Alina Donea

We estimate the main-sequence age and heavy-element abundance of the Sun by means of an asteroseismic calibration of theoretical solar models using only low-degree acoustic modes from the BiSON. The method can therefore be applied also to…

Solar and Stellar Astrophysics · Physics 2015-05-30 G. Houdek , D. O. Gough

The accurate prediction of precipitation is important to allow for reliable warnings of flood or drought risk in a changing climate. However, to make trust-worthy predictions of precipitation, at a local scale, is one of the most difficult…

Computation · Statistics 2021-02-26 Sherman Lo , Peter Watson , Peter Dueben , Ritabrata Dutta

The estimation of total solar irradiance falling on the earth's surface is important in the field of solar energy generation and forecasting. Several clear-sky solar radiation models have been developed over the last few decades. Most of…

Atmospheric and Oceanic Physics · Physics 2017-08-30 Soumyabrata Dev , Shilpa Manandhar , Yee Hui Lee , Stefan Winkler

Sunquakes are one of the more distinct secondary phenomena related to solar flares, where energy deposition in the lower layers of the Sun's atmosphere excites acoustic waves easily visible in Helioseismic and Magnetic Imager (HMI)…

Solar and Stellar Astrophysics · Physics 2021-02-04 John T. Stefan , Alexander G. Kosovichev

Models of diffusion MRI within a voxel are useful for making inferences about the properties of the tissue and inferring fiber orientation distribution used by tractography algorithms. A useful model must fit the data accurately. However,…

Quantitative Methods · Quantitative Biology 2017-02-08 Ariel Rokem , Jason D. Yeatman , Franco Pestilli , Kendrick N. Kay , Aviv Mezer , Stefan van der Walt , Brian A. Wandell

Local mixing-length theory is incapable of describing nonlocal phenomena in stellar convection, such as overshooting. Therefore standard solar models constructed with the local mixing-length theory deviate significantly from the Sun at the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Chunguang Zhang , Licai Deng , Darun Xiong , Jørgen Christensen-Dalsgaard