E-Print Archive

There are 4050 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
On active region loops: Hinode/EIS observations View all abstracts by submitter

Durgesh Tripathi   Submitted: 2008-12-31 06:15

We have carried out a study of active region loops using observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode using 1~arcsec~raster data for an active region observed on May 19, 2007. We find that active region structures which are clearly discernible in cooler lines (approx~1MK) become 'fuzzy' at higher temperatures (approx~2MK). The active region was comprised of red-shifted emissions (downflows) in the core and blue-shifted emissions (upflows) at the boundary. The flow velocities estimated in two regions located near the foot points of coronal loop showed red-shifted emission at transition region temperature and blue shifted emission at coronal temperature. The upflow speed in these regions increased with temperature. For more detailed study we selected one particular well defined loop. Downward flows are detected along the coronal loop, being stronger in lower temperature lines (rising up to 60 km s-1 near the foot point). The downflow was localized towards the footpoint in transition region lines (ion{Mg}{7}) and towards the loop top in high temperature line (ion{Fe}{15}). By carefully accounting for the background emission we found that the loop structure was close to isothermal for each position along the loop, with the temperature rising from around 0.8 MK to 1.5 MK from the close to the base to higher up towards the apex (approx~75Mm). We derived electron density using well established line ratio diagnostic techniques. Electron densities along the active region loop were found to vary from 10≲sup>10cm-3 close to the footpoint to 10≲sup>8.5cm-3 higher up. A lower electron density, varying from 10≲sup>9cm-3 close to the footpoint to 10≲sup>8.5cm-3 higher up, was found for the lower temperature density diagnostic. Using these densities we derived filling factors in along the coronal loop which can be as low as 0.02 near the base of the loop. The filling factor increased with projected height of the loop. These results provide important constraints on coronal loop modeling.

Authors: D. Tripathi, H.E.Mason, B. N. Dwivedi, G. Del Zanna, P.R. Young
Projects: None

Publication Status: Accepted for Publication in ApJ
Last Modified: 2008-12-31 07:13
Go to main E-Print page  Large Geomagnetic Storms: Introduction to Special Section   Observing the solar corona with a tunable Fabry-Perot filter  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
The Physical Nature of Spiral Wave Patterns in Sunspots
Predicting Solar Flares Using a Long Short-Term Memory Network
Coronal loop transverse oscillations excited by different driver frequencies
Solar Center-Limb Variation of the Strengths of Spectral Lines: Classification and Interpretation of Observed Trends
The plasmoid instability in a confined solar flare
High-frequency dynamics of active region moss as observed by IRIS
Extreme-ultraviolet Late Phase Caused by Magnetic Reconnection over Quadrupolar Magnetic Configuration in a Solar Flare
Two-step evolution of a rising flux rope resulting in a confined solar flare
Why torus-unstable solar filaments experience failed eruption?
The Magnetic Properties of Heating Events on High-Temperature Active Region Loops
Pulse-beam heating of deep atmospheric layers, their oscillations and shocks modulating the flare reconnection
A potential magnetic field calculator for solar physics applications using staggered grids
E and B polarizations from inhomogeneous and solar surface turbulence
Oscillations Accompanying a He I 10830 Å Negative Fare in a Solar Facula II. Response of the Transition Region and Corona
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

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