Distribution of jets and magnetic fields in a coronal hole

Kamio, S., H. Hara, T. Watanabe, and W. Curdt, Distribution of jets and magnetic fields in a coronal hole, A&A, 502, 345-353 (2009) (ADS)

The cartoon

(click on the image for a larger version)

X-ray jets, originally discovered by Yohkoh, are most visible in the polar coronal holes. These are flare-like actions, although it is well known that powerful flares can happen without much or any signficant jet action. The surprising thing about these coronal-hole jets is the presence of kilogauss field accumulations, perhaps best observed via Hinode due to its privileged location in space. This cartoon suggests a common explanation for these coronal jets and cool jets (see also the mini-filament idea), but why should a freely expanding jet flow on open fields result in higher temperatures than an equivalent energy release on closed fields?. What actions produce the kG fields? Is it flux emergence, or is it accumulation of flux from a broader area? What is the Poynting flux doing? Where is the role of helicity or vorticity? When and how does magnetic reconnection occur? There are lots of questions about these remarkable phenomena.

Date: 2011 February 25

Update: 2019 November 24