Computing Emissions from Active-Region Loops in 3D and High Resolution
Abstract
Plasma loops are widely observed in EUV and soft X-ray over active regions, but their thermal properties and formation mechanism have be controversial. In this work, we are able to reproduce some of the loop properties by forward modeling. Using an MDI magnetogram, we constructed a mildly sheared force-free magnetic field based on parameters deduced from observation. The field was computed in unusually high spatial resolution in order to resolve the expected thin coronal loops. Although the magnetogram has fine structures at the photospheric level, the field in the corona is smooth as expected. The field lines have moderately complex connectivity. We then chose a specific heating model and computed the thermal structure in 3D. Although the overall temperature profile has only moderate spatial variations in the corona, the computed line-of-sight integrated EUV emissions show a complex system of thin plasma loops. Initial analysis shows that thermal instability leads to the time variation of the loop brightness. The lack of cross-section expansion is also apparent. The location of the loops and their relationship with the magnetic field will also be discussed.
Work supported by HTP of NASA. Computation resources provided by NAS at Ames Research Center, NASA.- Publication:
-
AAS/Solar Physics Division Meeting #40
- Pub Date:
- May 2009
- Bibcode:
- 2009SPD....40.1208M