Determination of the true shape of coronal loops

作者：Alissandrakis C E; Gontikakis C^*; Dara H C

来源：Solar Physics, 2008, 252(1): 73-87.

DOI：10.1007/s11207-008-9242-4

• active regions, velocity field
• active regions, structure

Using line of sight velocity measurements from the SUMER and CDS instruments aboard SOHO, in conjunction with a simple geometrical model, we reconstructed the true, 3D shape and the velocity of plasma flow along coronal loops. The projection of the loop on the sky and the position of the footpoints define a family of curves. Assuming that the loop is located on a plane, the line of sight velocity can be used to select the most plausible solution. For two loops, observed in the Ne VIII 770 angstrom and O v 630 angstrom spectral lines, we find asymmetric, subsonic uni-directional flows, with velocity maxima of approximate to 80 kms(-1) near the footpoints. The loops are highly inclined with respect to the vertical, by 55 degrees and 70 degrees, respectively; thus the true height of the loop tops from the photospheric level is approximate to 20 '', comparable to the isothermal scale height.

• 出版日期2008-10