Twisting solar coronal jet launched at the boundary of an active region
Guillaume Aulanier Submitted: 2013-09-20 02:41
A broad jet was observed in a weak magnetic field area at the edge of active region NOAA
11106 that also produced other nearby recurring and narrow jets. The peculiar shape and magnetic
environment of the broad jet raised the question of whether it was created by the same
physical processes of previously studied jets with reconnection occurring high in the corona.
We carried out a multi-wavelength analysis using the EUV images from the
Atmospheric Imaging Assembly (AIA) and magnetic fields from the Helioseismic and Magnetic
Imager (HMI) both on-board the SDO satellite, which we coupled to a high-resolution, nonlinear
force-free field extrapolation. Local correlation tracking was used to identify the photospheric
motions that triggered the jet, and time-slices were extracted along and across the jet to unveil its
complex nature. A topological analysis of the extrapolated field was performed and was related
to the observed features.
The jet consisted of many different threads that expanded in around 10 minutes to about
100 Mm in length, with the bright features in later threads moving faster than in the early ones,
reaching a maximum speed of about 200 km s-1. Time-slice analysis revealed a striped pattern
of dark and bright strands propagating along the jet, along with apparent damped oscillations
across the jet. This is suggestive of a (un)twisting motion in the jet, possibly an Alfvén wave.
Bald patches in field lines, low-altitude flux ropes, diverging flow patterns, and a null point were
identified at the basis of the jet.
Unlike classical or Eiffel-tower shaped jets that appear to be caused by reconnection
in current sheets containing null points, reconnection in regions containing bald patches
seems to be crucial in triggering the present jet. There is no observational evidence that the flux
ropes detected in the topological analysis were actually being ejected themselves, as occurs in the
violent phase of blowout jets; instead, the jet itself may have gained the twist of the flux rope(s)
through reconnection. This event may represent a class of jets different from the classical quiescent
or blowout jets, but to reach that conclusion, more observational and theoretical work is
Authors: Schmieder B., Guo Y., Moreno-Insertis F., Aulanier G., Yelles Chaouche L., Nishizuka N., Harra L.K., Thalmann J.K., Vargas Dominguez S., Liu Y.
Publication Status: A&A, in press
Last Modified: 2013-09-22 08:03