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Time-distance helioseismic measurements in surface- and deep-focus geometries for wave-paths that distinguish surface magnetic contributions from those due to deeper perturbations beneath a large sunspot are presented and analysed. Travel…

天体物理学 · 物理学 2008-02-21 S. P. Rajaguru

We present a comprehensive study of one method for measuring various parameters of global modes of oscillation of the Sun. Using velocity data taken by the Michelson Doppler Imager (MDI), we analyze spherical harmonic degrees l <= 300. Both…

太阳与恒星天体物理 · 物理学 2015-11-18 Tim Larson , Jesper Schou

We apply the helioseismic methodology of Legendre Function Decomposition to 88 months of Dopplergrams obtained by the Helioseismic and Magnetic Imager (HMI) as the basis of inferring the depth variation of the mean meridional flow, as…

太阳与恒星天体物理 · 物理学 2021-04-21 D. C. Braun , A. C. Birch , Y. Fan

Surface granulation of the Sun is primarily a consequence of thermal transport in the outer 1 % of the radius. Its typical scale of about 1 - 2 Mm is set by the balance between convection, free-streaming radiation, and the strong density…

太阳与恒星天体物理 · 物理学 2015-06-18 Shravan M. Hanasoge , Katepalli R. Sreenivasan

We analyze and interpret SOHO/MDI data on oscillation frequency changes between 1996 and 2004 focusing on differences between activity minimum and maximum of solar cycle 23. We study only the behavior of the centroid frequencies, which…

天体物理学 · 物理学 2009-11-10 W. A. Dziembowski , P. R. Goode

Wave theories of heating the chromosphere, corona, and solar wind due to photospheric fluctuations are strengthened by the existence of observed wave coherency up to the transition region (TR). The coherency of solar spicules' intensity…

太阳与恒星天体物理 · 物理学 2017-02-08 Alireza Ahangarzadeh Maralani , Ehsan Tavabi , Ali Ajabshirizadeh

Emerging active regions are associated with convective flows on the spatial scale and lifetimes of supergranules. To understand how these flows are involved in the formation of active regions, we aim to identify where active regions emerge…

太阳与恒星天体物理 · 物理学 2024-07-17 Hannah Schunker , William Roland-Batty , Aaron C. Birch , Douglas C. Braun , Robert H. Cameron , L. Gizon

The 1-D mean-field equation describing the evolution of the subsurface toroidal field can be used together with the observed surface radial field to model the subsurface toroidal flux density. We aim to test this model and determine the…

太阳与恒星天体物理 · 物理学 2019-10-16 Robert Cameron , Jie Jiang

(abridged) We investigate how the properties of the corona and solar wind in the open coronal holes depend on the properties of the magnetic fields and their footpoint motions at the surface, by perfoming 1D MHD simulations from the…

天体物理学 · 物理学 2015-06-24 Takeru K. Suzuki , Shu-ichiro Inutsuka

Helioseismology has revealed that the angular velocity of the Sun increases with depth in the outermost 35 Mm of the Sun. Recently, we have shown that the logarithmic radial gradient ($\rm d\ln\Omega/\rm d\ln r $) in the upper 10~Mm is…

太阳与恒星天体物理 · 物理学 2016-11-02 Atefeh Barekat , Jesper Schou , Laurent Gizon

Photospheric waves in sunspots moving radially outwards at speeds faster than the characteristic wave velocities have been recently detected. It has been suggested that they are the visual pattern of $p-$modes excited around 5 Mm beneath…

太阳与恒星天体物理 · 物理学 2017-02-22 T. Felipe , E. Khomenko

Convection in a colloidal suspension with a large negative separation ratio is studied experimentally by heating from above. Shadowgraph observation at very large solutal Rayleigh numbers are reported as a function of time. Fast relaxation…

软凝聚态物质 · 物理学 2009-11-07 R. Cerbino , A. Vailati , M. Giglio

The sub-arcsec bright points (BP) associated with the small scale magnetic fields in the lower solar atmosphere are advected by the evolution of the photospheric granules. We measure various quantities related to the horizontal motions of…

太阳与恒星天体物理 · 物理学 2012-05-28 LP. Chitta , A. A. van Ballegooijen , L. Rouppe van der Voort , E. E. DeLuca , R. Kariyappa

The review presents analysis and physical interpretation of available statistical data about solar wind plasma and interplanetary magnetic field (IMF) properties as measured in-situ at 1 A.U. by numerous space experiments during time period…

空间物理 · 物理学 2013-01-15 A. V. Dmitriev , A. V. Suvorova , I. S. Veselovsky

The power spectrum of light curves from satellites like CoRoT and TESS of massive main-sequence stars show stochastic low-frequency (SLF) variability. To investigate the origin of this phenomenon, we conducted high-resolution 3D…

太阳与恒星天体物理 · 物理学 2026-02-16 Praneet Pathak , Simon Blouin , Falk Herwig , Paul R. Woodward

Various types of inertial modes have been observed and identified on the Sun, including the equatorial Rossby modes, critical-latitude modes, and high-latitude modes. Recent observations further report a detection of…

太阳与恒星天体物理 · 物理学 2023-11-20 Yuto Bekki

Direct seismic imaging of sub-surface flow, sound-speed and magnetic field is crucial for predicting flux tube emergence on the solar surface, an important ingredient for space weather. The sensitivity of helioseismic mode-amplitude…

太阳与恒星天体物理 · 物理学 2022-11-30 Srijan Bharati Das

The Solar and Heliospheric Observatory (SOHO) was launched in December 1995 with a suite of instruments designed to answer long-standing questions about the Sun's internal structure, its extensive outer atmosphere, and the solar wind. This…

天体物理学 · 物理学 2007-05-23 Steven R. Cranmer

Extreme-ultraviolet images from the Solar Dynamics Observatory often show looplike fine structure to be present where no minority-polarity flux is visible in magnetograms, suggesting that the rate of ephemeral region (ER) emergence inside…

太阳与恒星天体物理 · 物理学 2021-04-14 Y. -M. Wang

Temporal variations of the subsurface meridional flow with the solar cycle have been reported by several authors. The measurements are typically averaged over periods of time during which surface magnetic activity existed in the regions…

天体物理学 · 物理学 2008-09-05 I. Gonzalez Hernandez , S. Kholikov , F. Hill , R. Howe , R. Komm