XRT Picture of the Week (XPOW)

XRT Home XRT Mission Ops YouTube

2016 August 23

Click for movie. Also available on YouTube.

Dark and Bright Chewy Nougats

Earlier this month, the Sun gave us a very sweet treat. On 2 August 2016 Hinode XRT observed this lovely coronal cavity (filament cavity) duo on the west limb.

In the XRT image, seen in the movie, the northern ring has a darker than normal center and the smaller, southern ring has a bright X-ray center. These loop structures are nowhere near an active region so what's going on up there?

To find out why these rings exist, we must look at H-alpha data. H-alpha is a particular wavelength of light, 656.28 nm, that is useful for seeing solar filaments and prominences. When we overlay the XRT image onto a NSO/Gong H-alpha image, we see that both coronal cavities sit directly above two separate prominences.

The upper cavity has a dark center because the prominence sits high up into the corona and is actually blocking some of the X-rays -- a dark chewy nougat. This actually appears bright in the composite image because the prominence is bright in H-alpha.

However, the prominence in the lower ring does not extend high up into the cavity and doesn't block any X-rays. In fact, a bright X-ray core, has developed above it. -- a traditional chewy nougat.

Whether the cavity has a chewy nougat core or not, coronal cavities are complex magnetic structures that are a source of space weather. Interested readers can visit here for more information.

Keywords: Cavity, Limb
Filters: thin_Be

(Prepared by Patricia Jibben)

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