Recently, bright S's have been popular among solar physicists, especially those who study flares and CMEs. These S's are called 'sigmoids,' and they are usually observed as bright structures in soft X-rays. They are known to be a signature of highly sheared magnetic field in an active region, which thus has a high potential for energetic flares
In other news, I bought a pair of shoes (the old pair were starting to leak in the rain, through over-scuffed suede uppers and you-pedal-too-hard cracks in the soles). Apparently they're high performance walking shoes, even though I bought them from a fashion shop (Cult Clothing Sale Shop, purveyors of knock-down hawaiian shirts and tops to give to skinny sisters), so I should be sorted if Oxford suddenly turns into a rocky moutainside. Bah; I've been wearing them all afternoon, and there's one thing they want to do and it's not hike up a mountainside. These shoes were made for dancing.
However, the 'S' here is not an X-ray sigmoid but one falling into a rather traditional category: a dark filament. This one shows a very gorgeous 'S' shape in the extreme ultraviolet, though it can, of course, be seen in routine H-alpha image. It was clearly located on a magnetic inversion line, which bends like an 'S' around the region in question.
Sunshine. This morning I woke up and looked out of the window, and saw sunshine. It's light even now, and the traffic noise has that quiet clarity it only gets on a warm evening. I tried to read my VoxPolitics Primer (how to use the internet effectively, securely, and legally in election campaigns) but barely got past the introduction. I'm out of tune with my work. Was I ever in tune with it? What do I think is important? Do I care about my objectives? Even though I wrote them? Unhelpful thoughts. I've been drinking too much coffee today and not enough cammomile tea. Though that can dent my mood much. No day which starts with the postman bringing me a parcel containing a golden disco suit for Action Man made by my housemate's mother can't be a bad day. But that tea, now...
What is interesting is that this dark 'S' erupted near the west limb and caused a flare just like an X-ray sigmoid may do!
What do the names Vessela Howell and Jason Nicolson suggest to you? I've just realised that quite a lot of the local sites I've been looking around follow one Adobe Golive design and those seem to be the names associated with them. I can't find their homesites. Maybe they're too busy making sites for other people ...
During the week, the activity on the sun was not so high, although a few M-class flares were reported. Instead, several long filaments crawled quietly on the disk, and one of them strongly drew one's attention because of its beautiful S-shape. However, it was too faint in soft X-rays to be chosen as Yohkoh's observation target, which is usually set to the brightest region on the disk. It seemed to pass across the disk and go away with its stylish shape remaining. However, it was an old fox! It did erupt just before hiding away behind the limb, and Yohkoh caught its tail!
I used to worry a lot more than I do now. I wonder if this carries on throughout your life. Maybe that's why my parents act the way that they do.
Judging from the GOES flux variations (flares), it was a mediocre and boring week, but from a CME point of view it was highly active and exciting. The CME associated with the eruption of the dark 'S' was accompanied only by a small peak in soft X-ray flux. Even this was just a coincidence; the SXT images show that an entirely different region flared. The CME-related arcade appeared clearly in the X-ray images, but type of CME counterpart could hardly be termed outstanding, because of the faintness of the arcade. This event shows an example of a type of CME, for which the soft X-ray morphology, not just the X-ray brightness, should be used in a forecast.
Hmp. I just discovered that I should be taking all my holiday before March. Huh. Things are getting worse. Or better, if you take the view that the holiday I have left is time I can take at home instead of at work. Better, I think. Yes. Better, definitely.
This may be further evidence for recent exciting work which suggets that flare productivity and CME productivity seem to be somewhat uncoupled, and offer the suggestion that flares may represent relaxations following energy buildup, whereas CMEs may represent relaxations following magnetic helicity buildup.
Stare at the sun on the MSU Solar Physics Group website.