E-Print Archive

There are 4036 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
Non-Maxwellian analysis of the transition-region line profiles observed by the Interface Region Imaging Spectrograph View all abstracts by submitter

Jaroslav Dud   Submitted: 2017-06-16 10:27

We investigate the nature of the spectral line profiles for transition region ions observed with the Interface Region Imaging Spectrograph (IRIS). In this context, we have analyzed an active-region observation performed by IRIS in its 1400 Å spectral window. The transition-region lines are found to exhibit significant wings in their spectral profiles, which can be well-fitted with non-Maxwellian kappa-distribution. The fit with a kappa-distribution can perform better than a double Gaussian fit, especially for the strongest line, Si IV 1402.8 A. Typical values of κ found are about 2, occurring in a majority of spatial pixels where the transition region lines are symmetric, i.e., the fit can be performed. Furthermore, all five spectral lines studied (from Si IV, O IV and S IV) appear to have the same FWHM irrespective of whether the line is an allowed or an intercombination transition. A similar value of kappa is obtained for the electron distribution by fitting of the line intensities relative to Si IV 1402.8 A, if photospheric abundances are assumed. The kappa-distributions however do not remove the presence of non-thermal broadening. Instead, they actually increase the non-thermal width. This is because for kappa-distributions the transition-region ions are formed at lower temperatures. The large observed non-thermal width lowers the opacity of the Si IV line sufficiently enough for this line to become optically thin.

Authors: J. Dudík, V. Polito, E. Dzifčáková, G. Del Zanna, and P. Testa
Projects: IRIS

Publication Status: The Astrophysical Journal, in press
Last Modified: 2017-06-20 16:12
Go to main E-Print page  Electron plasma wake field acceleration in solar coronal and chromospheric plasmas  Non-Equilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)  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
Flare reconnection-driven magnetic field and Lorentz force variations at the Sun's surface
Why Does the Solar Corona Abnormally Rotate Faster Than the Photosphere?
Impacts On Proton Fluxes Observed During Different Interplanetary Conditions
Coronal Loop Seismology Using Standing Kink Oscillations With a Lookup Table
Data-Optimized Coronal Field Model: I. Proof of Concept
Coronal Bright Points
Difference of source regions between fast and slow coronal mass ejections
Invited Review: Signatures of Magnetic Flux Ropes in the Low Solar Atmosphere Observed in High Resolution
Do Kepler superflare stars really include slowly-rotating Sun-like stars ? - Results using APO 3.5m telescope spectroscopic observations and Gaia-DR2 data -
Magnetically Induced Current Piston for Generating Extreme-ultraviolet Fronts in the Solar Corona
Magnetic Field Dynamics and Varying Plasma Emission in Large-scale Coronal Loops
Nonlinear Evolution of Ion Kinetic Instabilities in the Solar Wind
What determines the X-ray intensity and duration of a solar flare?
Fast Magnetoacoustic Wave Trains with Time-dependent Drivers
Three-dimensional reconstruction of CME-driven shock-streamer interaction from radio observations: a different take on the diagnostics of coronal magnetic fields
The soft X-ray spectrometer polarimeter SolpeX
Variable emission mechanism of a Type IV radio burst
Inference of magnetic field strength and density from damped transverse coronal waves
Frequency-Distance Structure of Solar Radio Sources Observed by LOFAR
The birth of a coronal mass ejection

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