E-Print Archive

There are 4507 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
What is the spatial distribution of magnetic helicity injected in a solar active region? View all abstracts by submitter

Etienne Pariat   Submitted: 2006-03-06 02:38

Magnetic helicity is suspected to play a key role in solar phenomena such as flares and coronal mass ejections. Several investigations have recently computed the photospheric flux of magnetic helicity in active regions. The derived spatial maps of the helicity flux density, called GA, have an intrinsic mixed-sign patchy distribution. Pariat et al. (2005) recently showed that GA is only a proxy of the helicity flux density, which tends to create spurious polarities. They proposed a better proxy, G heta. We investigate here the implications of this new approach on observed active regions. The magnetic data are from MDI/SoHO instrument and the photospheric velocities are computed by local correlation tracking. Maps and temporal evolution of GA and G heta are compared using the same data set for 5 active regions. Unlike the usual GA maps, most of our G heta maps show almost unipolar spatial structures because the nondominant helicity flux densities are significantly suppressed. In a few cases, the G heta maps still contain spurious bipolar signals. With further modelling we infer that the real helicity flux density is again unipolar. On time-scales larger that their transient temporal variations, the time evolution of the total helicity fluxes derived from GA and G heta show small differences. However, unlike GA, with G heta the time evolution of the total flux is determined primarily by the predominant-signed flux while the nondominant-signed flux is roughly stable and probably mostly due to noise. Our results strongly support the conclusion that the spatial distribution of helicity injected into active regions is much more coherent than previously thought: on the active region scale the sign of the injected helicity is predominantly uniform. These results have implications for the generation of the magnetic field (dynamo) and for the physics of both flares and coronal mass ejections.

Authors: Pariat E., Nindos A., Démoulin P., Berger M.A.
Projects: None

Publication Status: A&A accepted
Last Modified: 2006-03-06 02:38
Go to main E-Print page  Investigating SUMER Coronal Hole Observations: A Robust Method of Raster Reduction  Damped coronal loop oscillations: time-dependent results  Edit Entry  Download Preprint  Delete Entry 

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
The role and contribution of magnetic fields, characterized via their magnetic flux, to the statistical structuring of the solar atmosphere
Do periods of decayless kink oscillations of solar coronal loops depend on noise?
Automatic detection technique for solar filament oscillations in GONG data
Probing the Density Fine Structuring of the Solar Corona with Comet Lovejoy
Confined plasma transition from the solar atmosphere to the interplanetary medium
Extracting the Heliographic Coordinates of Coronal Rays using Images from WISPR/Parker Solar Probe
Two-spacecraft detection of short-period decayless kink oscillations of solar coronal loops
Genesis and Coronal-jet-generating Eruption of a Solar Minifilament Captured by IRIS Slit-raster Spectra
First detection of transverse vertical oscillation during the expansion of coronal loops
A New Position Calibration Method for MUSER Images
Sigmoid Formation Through Slippage of A Single J-shaped Coronal Loop
MHD Simulation of Homologous Eruptions from Solar Active Region 10930 Caused by Sunspot Rotation
Dropouts of Fully Stripped Ions in the Solar Wind: A Diagnostic for Wave Heating versus Reconnection
Plasma heating and nanoflare caused by slow-mode wave in a coronal loop
The Lyman-α Emission in a C1.4 Solar Flare Observed by the Extreme Ultraviolet Imager aboard Solar Orbiter
Imaging and Spectroscopic Observations of the Dynamic Processes in Limb Solar Flares
Evolution of the critical torus instability height and CME likelihood in solar active regions
A Magnetogram-matching Method for Energizing Magnetic Flux Ropes Toward Eruption
A 2D Model for Coronal Bright Points: Association with Spicules, UV bursts, Surges and EUV Coronal Jets
The relativistic solar particle event on 28 October 2021: Evidence of particle acceleration within and escape from the solar corona

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