Spectroscopic Constraints on the Dimension of Active Region Loops Along the Line of Sight

Abstract:

Understanding the cross sections of coronal loops and how they vary along the loop is important both for understanding coronal heating and how the loops are shaped by the coronal magnetic field. To better address this question we have developed a new method to constrain the dimension of loops along the line of sight by utilizing spectroscopic observations. We apply this method to a cool (5.5<logT<6.2) loop using data from the Hinode/EUV Imaging Spectrometer (EIS) with supporting data from Solar Dynamic Observatory (SDO) and the Solar TErrestrial RElations Observatory (STEREO), and discuss the results and their limitations. Our results are consistent with circular loop cross sections, but could also be consistent with aspect ratios of 2 or 3.