DOT tomography of the solar atmosphere

V. Analysis of a surge from AR10486

¹ Sterrekundig Instituut, Utrecht University, Postbus 80 000, 3508 TA Utrecht, The Netherlands e-mail: [k.tziotziou;p.suetterlin]@astro.uu.nl
² National Observatory of Athens, Institute for Space Applications and Remote Sensing, Lofos Koufos, 15236 Palea Penteli, Greece e-mail: georgia@space.noa.gr

Received: 9 June 2005
Accepted: 9 August 2005

Abstract

We present an analysis of high temporal and spatial resolution CaII H chromospheric limb observations obtained with the Dutch Open Telescope (DOT). We focus on a solar surge observed both by the DOT in CaII H and the Transition Region and Coronal Explorer (TRACE) satellite in the 195 Å and 1600 Å passbands. The surge is observed in active region AR10486 located near the solar limb, a region which two hours later produced the largest X-flare ever recorded. It consists of relatively cold gas of about 10 K. In TRACE images the surge is followed for almost 2.5 h, shrinking and expanding at the same location several times. From DOT images we find outward propagating intensity disturbances, with velocities higher than 50  km s^-1, indicative of upward material motion. The latter is also suggested by the good correlation between the DOT and TRACE surge apparent height curves, their apparent time delay and a phase difference analysis. A spectral wavelet analysis of the brightness variations within and along the surge shows a predominant period of ~6 min, the first ever reported for this kind of structures. Magnetic reconnection at the bottom of the surge as its driving mechanism is suggested by the observed inverted “Y” shape configuration and is further supported by a phase difference analysis.