paper

A swirling flare-related EUV jet

arXiv:1312.1374 · doi:10.1051/0004-6361/201322616

Abstract

{We report our observations of a swirling flare-related EUV jet on 2011 October 15.} {We utilised the EUV observations from SDO/AIA. We extracted a wide slit along the jet axis and 12 thin slits across its axis to investigate the longitudinal motion and transverse rotation. We also used data from STEREO/EUVI to investigate the 3D structure of the jet. Gound-based H images provide a good opportunity to explore the relationship between the cool surge and hot jet. LOS magnetograms from SDO/HMI enable us to study the magnetic evolution of the flare/jet event.} {The onset of jet eruption coincided with the start time of C1.6 flare impulsive phase. The initial velocity and acceleration of the longitudinal motion were 254 km s and m s, respectively. The jet presented helical structure and transverse swirling motion at the beginning of its eruption. The counter-clockwise rotation slowed down from an average velocity of 122 km s to 80 km s. The interwinding thick threads of the jet untwisted into multiple thin threads during the rotation that lasted for 1 cycle with a period of 7 min and an amplitude that increases from 3.2 Mm at the bottom to 11 Mm at the upper part. Afterwards, the curtain-like leading edge of the jet continued rising without rotation, leaving a dimming region behind before falling back to the solar surface. The appearance/disappearance of dimming corresponded to the longitudinal ascending/descending motions of jet. Cospatial H surge and EUV dimming imply that the dimming resulted from the absorption of hot EUV emission by cool surge. The flare/jet event was caused by continuous magnetic cancellation before the start of flare. The jet was associated with the open magnetic fields at the edge of AR 11314.}

15 pages, 11 figures

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