E-Print Archive

There are 3946 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
The magnetic helicity injected by shearing motions View all abstracts by submitter

Pascal Demoulin   Submitted: 2001-12-19 08:43

Photospheric shearing motions are one of the possible ways to inject magnetic helicity into the corona. We explore their efficiency as a function of their particular properties and those of the magnetic field configuration. Based on the work of M.A. Berger, we separate the helicity injection into two terms: twist and writhe. For shearing motions concentrated between the centres of two magnetic polarities the helicity injected by twist and writhe add up, while for spatially more extended shearing motions, such as differential rotation, twist and writhe helicity have opposite signs and partially cancel. This implies that the amount of injected helicity can change in sign with time even if the shear velocity is time independent. We confirm the amount of helicity injected by differential rotation in a bipole in the two particular cases studied by DeVore (2000), and further explore the parameter space on which this injection depends. For a given latitude, tilt and magnetic flux, the generation of helicity is slightly more efficient in young active regions than in decayed ones (up to a factor 2). The helicity injection is mostly affected by the tilt of the AR with respect to the solar equator. The total helicity injected by shearing motions, with both spatial and temporal coherence, is at most equivalent to that of a twisted flux tube having the same magnetic flux and a number of turns of 0.3. In the solar case, where the motions have not such global coherence, the injection of helicity is expected to be much smaller, while for differential rotation this maximum value reduces to 0.2 turns. We conclude that shearing motions are a relatively inefficient way to bring magnetic helicity into the corona (compared to the helicity carried by a significantly twisted flux tube).

Authors: Démoulin P., van Driel-Gesztelyi L., Mandrini C.H., Lòpez Fuentes M. & Aulanier, G.

Publication Status: Solar Physics, in press
Last Modified: 2001-12-19 08:43
Go to main E-Print page   What is the source of the magnetic helicity shed by CMEs.  The long-term helicity budget of AR 7978   Temperature Isotropization in Solar Flare Plasmas due to the Electron Firehose Instability  Edit Entry  Download Preprint  Submitter's Homepage 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
Coronal hard X-ray sources revisited
Manifestations of bright points observed in G-band and Ca II H by Hinode/SOT
Propagation of Leaky MHD Waves at Discontinuities with Tilted Magnetic Field
Time variations of the non-potential and volume-threading magnetic helicities
Advances in mean-field dynamo theory and applications to astrophysical turbulence
Reverse Current Model for Coronal Mass Ejection Cavity Formation
Predictions of DKIST/DL-NIRSP Observations for an Off-limb Kink-unstable Coronal Loop
Exploring the biases of a new method based on minimum variance for interplanetary magnetic clouds
The non-modal onset of the tearing instability
SpatioTemporal Evolution and North-South Asymmetry of Quasi-Biennial Oscillations in the Coronal Fe XIV Emission
Corotating Shock Waves and the Solar-Wind Source of Energetic Ion Abundances: Power Laws in A/Q
Coronal condensations caused by magnetic reconnection between solar coronal loops
Measurement of Vector Magnetic Field in a Flare kernel with a Spectropolarimetric Observation in He I 10830 A
The Relation Between Escape and Scattering Times of Energetic Particles in a Turbulent Magnetized Plasma: Application to Solar Flares
Implications of loop-top origin for microwave, hard X-ray, and low-energy gamma-ray emissions from behind the limb flares
Solar radio emission as a disturbance of aeronautical radionavigation
A Diagnostic of Coronal Elemental Behavior during the Inverse FIP Effect in Solar Flares
Observations of Turbulent Magnetic Reconnection Within a Solar Current Sheet
Diagnostic Analysis of the Solar Proton Flares of September 2017 by Their Radio Bursts
Densities Probed by Coronal Type III Radio Burst Imaging

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

© 2003 Solar Physics Group - Montana State University