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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 26, issue 10
Ann. Geophys., 26, 2967–2974, 2008
https://doi.org/10.5194/angeo-26-2967-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: SOHO 20 – Transient events on the Sun and in the...

Ann. Geophys., 26, 2967–2974, 2008
https://doi.org/10.5194/angeo-26-2967-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.

  15 Oct 2008

15 Oct 2008

Topologically driven coronal dynamics – a mechanism for coronal hole jets

D. A. N. Müller1 and S. K. Antiochos2 D. A. N. Müller and S. K. Antiochos
  • 1European Space Agency, Research and Scientific Support Department, c/o NASA Goddard Space Flight Center, Mail Code 671.1, Greenbelt, MD 20771, USA
  • 2Heliophysics Division, NASA Goddard Space Flight Center, Mail Code 674.0, Greenbelt, MD 20771, USA

Abstract. Bald patches are magnetic topologies in which the magnetic field is concave up over part of a photospheric polarity inversion line. A bald patch topology is believed to be the essential ingredient for filament channels and is often found in extrapolations of the observed photospheric field. Using an analytic source-surface model to calculate the magnetic topology of a small bipolar region embedded in a global magnetic dipole field, we demonstrate that although common in closed-field regions close to the solar equator, bald patches are unlikely to occur in the open-field topology of a coronal hole. Our results give rise to the following question: What happens to a bald patch topology when the surrounding field lines open up? This would be the case when a bald patch moves into a coronal hole, or when a coronal hole forms in an area that encompasses a bald patch. Our magnetostatic models show that, in this case, the bald patch topology almost invariably transforms into a null point topology with a spine and a fan. We argue that the time-dependent evolution of this scenario will be very dynamic since the change from a bald patch to null point topology cannot occur via a simple ideal evolution in the corona. We discuss the implications of these findings for recent Hinode XRT observations of coronal hole jets and give an outline of planned time-dependent 3-D MHD simulations to fully assess this scenario.

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