Letter to the Editor
Observations and 3D MHD simulations of a solar active region jet
Research Center for Astronomy and Applied Mathematics, Academy of Athens, 4 Soranou Efessiou Str., Athens 11527, Greece e-mail: email@example.com
2 School of Mathematics and Statistics. St. Andrews University, St. Andrews, KY16 9SS, UK
3 Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Athens, Panepistimiopolis, Zografos 157 84, Athens, Greece
Accepted: 22 September 2009
Aims. We study an active region jet originating from NOAA 8531 on May 15 1999. We perform 3D MHD numerical simulations of magnetic flux emergence and its subsequent reconnection with preexisting magnetic flux. Then, we compare the physical properties of the observed jet with the reconnecting outflow produced in the numerical model.
Methods. We report observations of this jet using a series of TRACE 171 Å filtergrams, simultaneous observations from SUMER in Ne viii 770Å and C iv 1548 Å as well as MDI magnetograms. In the numerical simulation, the full compressible and resistive MHD equations are solved, including viscous and Ohmic heating.
Results. A high-velocity upflow (100 km s-1) is observed after the emergence of new magnetic flux at the edge of the active region. The jet is recorded over a range of temperatures between 105 K and K. In our numerical experiments, we find that the jet is the result of magnetic reconnection between newly emerging flux and the preexisting magnetic field of the active region.
Conclusions. The hot and high-velocity bidirectional flows occur as a result of the interaction between oppositely directed magnetic fields. Observations and numerical results are strongly suggestive of effective reconnection process being responsible for producing jets when emerging flux appears in solar active regions.
Key words: magnetohydrodynamics (MHD) / methods: numerical / Sun: activity / Sun: corona / Sun: magnetic fields
© ESO, 2009