E-Print Archive

There are 4282 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
* News 04/04/20 * The archive is using a new backend database. This has thrown up a few SQL errors in the last few days. If you have any issues please email adavey@nso.edu with either the number of eprint you are trying to edit or a link to your preprint.

f-mode strengthening from a localized bipolar subsurface magnetic field View all abstracts by submitter

Axel Brandenburg   Submitted: 2020-05-23 01:40

Recent numerical work in helioseismology has shown that a periodically varying subsurface magnetic field leads to a fanning of the f-mode, which emerges from the density jump at the surface. In an attempt to model a more realistic situation, we now modulate this periodic variation with an envelope, giving thus more emphasis on localized bipolar magnetic structures in the middle of the domain. Some notable findings are: (i) compared to the purely hydrodynamic case, the strength of the f-mode is significantly larger at high horizontal wavenumbers k, but the fanning is weaker for the localized subsurface magnetic field concentrations investigated here than the periodic ones studied earlier; (ii) when the strength of the magnetic field is enhanced at a fixed depth below the surface, the fanning of the f-mode in the kω diagram increases proportionally in such a way that the normalized f-mode strengths remain nearly the same in different such cases; (iii) the unstable Bloch modes reported previously in case of harmonically varying magnetic fields are now completely absent when more realistic localized magnetic field concentrations are imposed beneath the surface, thus suggesting that the Bloch modes are unlikely to be supported during most phases of the solar cycle; (iv) the f-mode strength appears to depend also on the depth of magnetic field concentrations such that it shows a relative decrement when the maximum of the magnetic field is moved to a deeper layer. We argue that detections of f-mode perturbations such as those being explored here could be effective tracers of solar magnetic fields below the photosphere before these are directly detectable as visible manifestations in terms of active regions or sunspots.

Authors: Authors:Nishant K. Singh, Harsha Raichur, Maarit J. Käpylä, Matthias Rheinhardt, Axel Brandenburg, Petri J. Käpylä
Projects: None

Publication Status: Geophys. Astro. Fluid 2020, 114, 196-212 (2020)
Last Modified: 2020-05-27 13:13
Go to main E-Print page  Sunquake with a second-bounce, other sunquakes and emission associated with X9.3 flare of 6 September 2017.  II. Proposed interpretation  Imaging and spectral study on the null point of a fan-spine structure during a solar flare  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

Key
Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
Propagation Effects in Quiet Sun Observations at Meter Wavelengths
Twin Null-Point-Associated Major Eruptive Three-Ribbon Flares with Unusual Microwave Spectra
Trajectory Determination for Coronal Ejecta Observed by WISPR/Parker Solar Probe
Recurring Homologous Solar Eruptions in NOAA AR 11429
Resonant absorption: transformation of compressive motions into vortical motion
The depth and the vertical extent of the energy deposition layer in a medium-class solar flare
Helicity proxies from linear polarisation of solar active regions
The Submillimeter Active Region Excess Brightness Temperature during Solar Cycles 23 and 24
Nanoflare Diagnostics from Magnetohydrodynamic Heating Profiles
The Solar Orbiter mission - Science Overview
Time Series Analysis of Photospheric Magnetic Parameters of Flare-quiet versus Flaring Active Regions: Scaling Properties of Fluctuations
Image Quality Assessment for Full-Disk Solar Observations with Generative Adversarial Networks
Identifying and Tracking Solar Magnetic Flux Elements with Deep Learning
Active Region Irradiance During Quiescent Periods: New Insights from Sun-as-a-star Spectra
Probing solar flare accelerated electron distributions with prospective X-ray polarimetry missions
Accelerating and Supersonic Density Fluctuations in Coronal Hole Plumes: Signature of Nascent Solar Winds
Sequential Lid Removal in a Triple-Decker Chain of CME-Producing Solar Eruptions
RESIK and RHESSI observations of the 20 September 2002 flare
Starspot mapping with adaptive parallel tempering I: Implementation of computational code
Heating and Eruption of a Solar Circular Ribbon Flare

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2000-2020 Solar Physics Group - Montana State University