E-Print Archive

There are 3812 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
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.
Projects:

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 

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
Evolution of Photospheric Flow and Magnetic Fields Associated with The 2015 June 22 M6.5 Flare
Spatially inhomogeneous acceleration of electrons in solar flares
Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014
The origin, early evolution and predictability of solar eruptions
Polar Field Correction for HMI Line-of-Sight Synoptic Data
Relationship between Intensity of White-Light Flares and Proton Flux of Solar Energetic Particles
Spectroscopic Observations of a Current Sheet in a Solar Flare
IRIS Observations of Spicules and Structures Near the Solar Limb
Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673
Simultaneous observation of a flux rope eruption and magnetic reconnection during an X-class solar flare
Spectroscopic diagnostics of the non-Maxwellian κ-distributions using SDO/EVE observations of the 2012 March 7 X-class flare
Transient rotation of photospheric vector magnetic fields associated with a solar flare
Three-dimensional Forward-fit Modeling of the Hard X-Ray and Microwave Emissions of the 2015 June 22 M6.5 Flare
Center-to-Limb Variability of Hot Coronal EUV Emissions During Solar Flares
A time dependent relation between EUV solar flare light-curves from lines with differing formation temperatures
Understanding Breaks in Flare X-Ray Spectra: Evaluation of a Cospatial Collisional Return-current Model
Solar energetic particles and radio burst emission
A quasi-periodic fast-propagating magnetosonic wave associated with the eruption of a magnetic flux rope
Two-step solar filament eruptions
Regularized Biot-Savart Laws for Modeling Magnetic Flux Ropes

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