E-Print Archive

There are 4571 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Hydraulic effects in a radiative atmosphere with ionization View all abstracts by submitter

Axel Brandenburg   Submitted: 2016-05-19 23:19

In a paper of 1978, Eugene Parker postulated the need for hydraulic downward motion to explain magnetic flux concentrations at the solar surface. A similar process has recently also been seen in simplified (e.g., isothermal) models of flux concentrations from the negative effective magnetic pressure instability. We study the effects of partial ionization near the radiative surface on the formation of such magnetic flux concentrations. We first obtain one-dimensional (1D) equilibrium solutions using either a Kramers-like opacity or the H- opacity. The resulting atmospheres are then used as initial conditions in two-dimensional (2D) models where flows are driven by an imposed gradient force resembling a localized negative pressure in the form of a blob. To isolate the effects of partial ionization and radiation, we ignore turbulence and convection. In 1D models, due to partial ionization, an unstable stratification forms always near the surface. We show that the extrema in the specific entropy profiles correspond to the extrema in degree of ionization. In the 2D models without partial ionization, flux concentrations form close to the height where the blob is placed. In models with partial ionization, such flux concentrations form at the surface much above the blob. This is due to the corresponding unstable layer in specific entropy. With H- opacity, flux concentrations are weaker due to the stably stratified deeper parts. We demonstrate that, together with density stratification, the imposed source of negative pressure drives the formation of flux concentrations. We find that the inclusion of partial ionization affects entropy profiles causing the strong flux concentrations to form closer to the surface. We speculate that turbulence is needed to limit the strength of flux concentrations and homogenize the specific entropy to a more nearly marginal stratification.

Authors: Pallavi Bhat, Axel Brandenburg
Projects: None

Publication Status: Astron. Astrophys. 587, A90 (2016)
Last Modified: 2016-05-20 22:55
Go to main E-Print page  Why are flare ribbons associated with the spines of magnetic null points generically elongated?  Undamped transverse oscillations of coronal loops as a self-oscillatory process  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
Solar Radio Spikes and Type IIIb Striae Manifestations of Sub-second Electron Acceleration Triggered by a Coronal Mass Ejection
Statistical study of Type III bursts and associated HXR emissions
On orbit performance of the solar flare trigger for the Hinode EUV Imaging Spectrometer
Plasma Composition Measurements in an Active Region from Solar Orbiter/SPICE and Hinode/EIS
Modulation of cosmic ray anti-protons in the heliosphere: simulations for a solar cycle
Temporal and spatial association between microwaves and type III bursts in the upper corona
Prospective Implications of EUV Coronal Plumes for Magnetic-network Genesis of Coronal Heating, Coronal-hole Solar Wind, and Solar-wind Magnetic-field Switchbacks
Solar Energetic Particle Events with Short and Long Onset Times
The mechanism of magnetic flux rope rotation during solar eruption
Quantification of the Writhe Number Evolution of Solar Filament Axes
Starspot mapping with adaptive parallel tempering. II. Application to TESS data for M-dwarf flare stars, AU Microscopii, YZ Canis Minoris, and EV Lacertae
A Superflare on YZ Canis Minoris Observed by Seimei Telescope and TESS: Red Asymmetry of Hα Emission Associated with White-Light Emission
The frequency ratio and time delay of solar radio emissions with fundamental and harmonic components
Prospects of Detecting Non-thermal Protons in Solar Flares via Lyman Line Spectroscopy: Revisiting the Orrall-Zirker Effect
Rapid Rotation of an Erupting Prominence and the Associated Coronal Mass Ejection on 13 May 2013
Spectral and Imaging Diagnostics of Spatially-Extended Turbulent Electron Acceleration and Transport in Solar Flares
Detection of a high-velocity prominence eruption leading to a CME associated with a superflare on the RS CVn-type star V1355 Orionis
Magnetohydrodynamics Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model: I Cross-equatorial Interactions of Bands
Stability of slow magnetoacoustic and entropy waves in the solar coronal plasma with thermal misbalance
The chromosphere underneath a Coronal Bright Point

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