EDP Sciences
Free Access
Issue
A&A
Volume 421, Number 2, July II 2004
Page(s) L33 - L36
Section Letters
DOI https://doi.org/10.1051/0004-6361:20040186


A&A 421, L33-L36 (2004)
DOI: 10.1051/0004-6361:20040186

Letter

Vertical oscillations of a coronal loop observed by TRACE

T. J. Wang and S. K. Solanki

Max-Planck Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany (Previously known as MPI für Aeronomie.)

(Received 4 May 2004 / Accepted 26 May 2004 )

Abstract
We report on a loop oscillation event observed by TRACE in the 195 Å bandpass at the solar limb. The difference images reveal the first evidence for vertical kink oscillations of the loop, i.e., alternately expanding and shrinking motions, in contrast to horizontal transverse loop oscillations reported before, which exhibit swaying motions. Based on the 3D geometry of the oscillating loop derived from the observation by fitting with a circular or elliptical loop model, we simulate these two kinds of global kink modes and find that only the vertical oscillations produce a signature in the difference images in agreement with the observations. We also find that the oscillating loop is associated with intensity variations. Based on the measured displacement amplitude, the simulation predicts an intensity variation of about 13% due to density changes produced by the change of the loop length. The observed intensity changes have the same sign but are considerably larger than the predictions although the error bars are also large. This suggests that these oscillations are compressible.


Key words: Sun: corona -- flares -- oscillations -- UV radiation

Offprint request: T. J. Wang, wangtj@linmpi.mpg.de




© ESO 2004

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.