Several large, bright active regions were visible on the Sun on 23 January 2016. These regions have a large X-ray void between them that is often referred to as an
magnetic x-point or magnetic null region high in the corona.
Hinode XRT was observing the large active region in the south when it observed a dark cusp outlined in bright X-ray emission. The cusp shape is a good indicator that
magnetic reconnection is happening. Normally, this cusp would be filled with super hot, bright X-ray emission.
An AIA composite image shows that the X-ray void is filled with cool plasma so we have an example of cool reconnection.
Keywords: Cusp, X-Point