Sunspotter Talk

Notable Image (with unusual artifact)?

  • Mjtbarrett by Mjtbarrett Notable image (with strong polarity separation line) which led to a major flare. There's also an unusual linear feature (?artifact) that crosses the PSL and is visible in both the -ve and +ve regions. It looks a bit like a line of dots on a slightly curved path...

    Solarmonitor has this AR09026 and lists three X class flares amongst others. The Fe XV (284 A) image shows a number of artifacts: that could be CR hits on the CCD module (possibly during a solar storm)? The artifact in DSZ000003j looks unusual though... Unlike other CR hits that I've seen which are usually much brighter and blockier. Any thoughts on the cause of the artifact please?

    There's a really good NASA Science account of this sunspot and moving pictures in colour from it here: just like being at the pictures so get some popcorn ready... 😃


  • pahiggins by pahiggins

    I think the feature you are referring to is physical in origin. My guess is that it is either A. a 'real' representation of the line-of-sight magnetic field in that location, or B. it is due to one of the X-ray flares that you mention.

    A. there is likely to be strong shearing (motion in the plasma that acts in opposite directions along an interface and stretches/elongates/shreds the field)

    B. because X-ray flares are so bright, they may actually distort the observed visible-light emission line (a singingly-ionised nickel line at ~6000 angstroms). Normally flares are not seen in the visible light range because the sun's surface is so bright in this range. At x-ray and EUV wavelengths, the non-active sun is not very bright, so flares can be seen easily. But X-ray flares can compete with the background brightness of the Sun, around the flare site. This causes problems when we are trying to measure the magnetic field. So, that may be the cause of that narrow strip of white/black over the PSL in this case.

    Check out a movie of NOAA active region 11158 during the February 10-20, 2011 X-class flares, and look how the magnetic field changes during the flare time. Sorry I don't have a link on hand...


  • Mjtbarrett by Mjtbarrett

    Hello @pahiggins,
    Thank you for the reply! The line of dots seen on maximum zoom looked a bit unusual, almost as if it was a fast moving object moving across the FOV like a multiple exposure (rather than the streak of light seen by car headlights in a long exposure if you see what I mean). I found the following links if they are of interest:



    And include the protons just out of interest 😃