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Related papers: Inferring photospheric horizontal flows from multi…

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Urban heatwaves, droughts, and land degradation are pressing and growing challenges in the context of climate change. A valuable approach to studying them requires accurate spatio-temporal information on land surface conditions. One of the…

Machine Learning · Computer Science 2025-08-01 Sofiane Bouaziz , Adel Hafiane , Raphael Canals , Rachid Nedjai

Scene flow estimation aims to generate the 3D motion field of points between two consecutive frames of point clouds, which has wide applications in various fields. Existing point-based methods ignore the irregularity of point clouds and…

Computer Vision and Pattern Recognition · Computer Science 2025-01-22 Xuezhi Xiang , Xi Wang , Lei Zhang , Denis Ombati , Himaloy Himu , Xiantong Zhen

Quiet-Sun regions cover most of the Sun's surface; its magnetic fields contribute significantly to the solar chromospheric and coronal heating. However, characterizing the magnetic fields of the quiet Sun is challenging due to their weak…

Solar and Stellar Astrophysics · Physics 2024-12-02 Jiayi Liu , Xudong Sun , Peter W. Schuck , Sarah A. Jaeggli

Accurate estimation of thermospheric density is critical for precise modeling of satellite drag forces in low Earth orbit (LEO). Improving this estimation is crucial to tasks such as state estimation, collision avoidance, and re-entry…

The uncertainty of the energy generated by photovoltaic systems incurs an additional cost for a guaranteed, reliable supply of energy (i.e., energy storage). This investigation aims to decrease the additional cost by introducing…

Machine Learning · Computer Science 2023-01-19 Guillermo Terrén-Serrano , Manel Martínez-Ramón

Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler…

We present a direct comparison between two different techniques time-distance helioseismology and a local correlation tracking method for measuring mass flows in the solar photosphere and in a near-surface layer: We applied both methods to…

Astrophysics · Physics 2009-11-13 Michal Svanda , Junwei Zhao , Alexander G. Kosovichev

Stellar surface processes represent a fundamental limit to the detection of extrasolar planets with the currently most heavily-used techniques. As such, considerable effort has gone into trying to mitigate the impact of these processes on…

Solar and Stellar Astrophysics · Physics 2014-08-07 Fabienne A. Bastien

We compare the average photospheric current helicity $H_c$, photospheric twist parameter $\alpha$ (a well-known proxy for the full relative magnetic helicity), and subsurface kinetic helicity $H_k$ for 194 active regions observed between…

Solar and Stellar Astrophysics · Physics 2015-06-22 Darryl Seligman , Gordon Petrie , Rudi Komm

Solar torsional oscillations are migrating bands of slower- and faster-than-average rotation, which are strongly related to the Sun's magnetic cycle. We perform a long-term study (16 yr) of hemispherical asymmetry in solar torsional…

Solar and Stellar Astrophysics · Physics 2018-08-01 Lekshmi B , Dibyendu Nandy , H M Antia

Stellar activity induced by active structures (eg, spots, faculae) is known to strongly impact the radial velocity time series. It then limits the detection of small planetary RV signals (eg, an Earth-mass planet in the habitable zone of a…

Solar and Stellar Astrophysics · Physics 2015-09-23 Simon Borgniet , Nadège Meunier , Anne-Marie Lagrange

We analyse mesogranular flow patterns in a three-dimensional hydrodynamical simulation of solar surface convection in order to determine its characteristics. We calculate divergence maps from horizontal velocities obtained with the Local…

Solar and Stellar Astrophysics · Physics 2015-05-19 Ł. Matloch , R. Cameron , S. Shelyag , D. Schmitt , M. Schüssler

Solar active regions (ARs) that produce major flares typically exhibit strong plasma shear flows around photospheric magnetic polarity inversion lines (MPILs). It is therefore important to quantitatively measure such photospheric shear…

Solar and Stellar Astrophysics · Physics 2018-10-29 Sung-Hong Park , Jordan A. Guerra , Peter T. Gallagher , Manolis K. Georgoulis , D. Shaun Bloomfield

The interaction of magnetic fields and convection is investigated in the context of the coronal heating problem. We study the motions of photospheric magnetic elements using filtergrams obtained at the Swedish Vacuum Solar Telescope at La…

A saliency guided hierarchical visual tracking (SHT) algorithm containing global and local search phases is proposed in this paper. In global search, a top-down saliency model is novelly developed to handle abrupt motion and appearance…

Computer Vision and Pattern Recognition · Computer Science 2018-12-24 Fangwen Tu , Shuzhi Sam Ge , Yazhe Tang , Chang Chieh Hang

The prospect of combining integral field spectroscopy with the solar gravitational lens (SGL) to spectrally and spatially resolve the surfaces and atmospheres of extrasolar planets is investigated. The properties of hyperbolic orbits…

Instrumentation and Methods for Astrophysics · Physics 2022-05-02 Alexander Madurowicz , Bruce Macintosh

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

Aims. We study the coherency of solar spicules intensity oscillations with increasing height above the solar limb in quiet Sun, active Sun and active region using observations from HINODE/SOT. Existence of coherency up to transition region…

Solar and Stellar Astrophysics · Physics 2015-07-15 E. Tavabi , A. Ajabshirizadeh , A. R. Ahangarzadeh Maralani , S. Zeighami

Observations of the solar surface reveal the presence of flows with length scales of around $35$ Mm, commonly referred to as supergranules. Inferring the sub-surface flow profile of supergranules from measurements of the surface and…

Solar and Stellar Astrophysics · Physics 2016-08-03 Jishnu Bhattacharya , Shravan M. Hanasoge

Aims. We show how the build-up of magnetic gradients in the Sun's corona may be inferred directly from photospheric velocity data. This enables computation of magnetic connectivity measures such as the squashing factor without recourse to…

Solar and Stellar Astrophysics · Physics 2015-05-30 A. R. Yeates , G. Hornig , B. T. Welsch