Solar Cycle 24 Main Discussion IX

[bradk]

af4ex-

Too bad, looks like she will fade too oblivion once again. We missed 1138's firworks by a very small amount though!

[af4ex]

It ain't over till it's over. The activity may come in spurts. I think she still has some mileage to go.

[af4ex]

... and the x-ray background level is picking up. Normally it's below 10^-7 w/m². So everything above that we can safely assume is due to 1147. (I don't think that new unamed region in the southwest would have that much influence).

There was a curious x-ray lull yesterday. Not sure if that was a real drop in activity, or a artifact of observation caused by the directionality of the x-ray radiation pattern. It may not be "isotropic" (meaning: radiating equally in all directions). As the Sun rotates we view the radiation coming from a region at different angles. Changes occur more abruptly on the excursion over the limb.

Dr. Svalgaard, do you know if x-ray radiation from these regions is isotropic?

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[af4ex]

I said:
> ... I don't think that new unamed region in the southwest would
> have that much influence.

I retract that statement. The newbie region (1148?) seems to have become much stronger and is emitting B-class flares.

You can see the latest SDO movie of it here sprouting out of nowhere, and then flaring up [viewable only for next 48hrs]:
sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0171.mpg

[edit: hmm, my attachment went blank for some reason. Use your imagination to fill in the missing solar disk ]

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[af4ex]

I said:
> The newbie region (1148?) seems to have become much
> stronger and is emitting B-class flares.

1148 is strong, but 1147 proved to be more active: 10 B-class flares yesterday and 3 already today. 1148 seems to have only one B-class (anonymous, before 1148 was named).

Both regions seem to be growing in the visible wavelengths. Activity is definitely going up, as you can see by the other leading solar indices.

Penticton
Date MHZ 1700Z 2000Z 2300Z
2011 Jan 12 2800 80 80 80
2011 Jan 13 2800 80 80 79
2011 Jan 14 2800 80 79 79
2011 Jan 15 2800 81 80 80
2011 Jan 16 2800 81 80 80
2011 Jan 17 2800 81 82 82

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[af4ex]

This is interesting. On Jan 15, as AR1147 was rotating into view, the radioheliograph at Nancay, France captured very large bursts of RF (VHF and UHF) synchrotron radiation in the corona above.
bass2000.obspm.fr/home.php

This is a well-known phenomenon, caused by charged particles accelerating at relativistic speeds.
www.ursi.org/Proceedings/ProcGA05/pdf/J05.5(0544).pdf

Normally these bursts are much smaller, but this the biggest I've seen. Note that the burst appears larger in VHF. I believe this is because of the weaker magnetic fields, lowering the gyro-frequencies as altitude increases.

NOAA/USAF claim to track radio bursts, but haven't reported any which match their criteria since last year. Perhaps these are not the kind of bursts they're interested in:
www.swpc.noaa.gov/ftpdir/lists/radio

There's an interesting chart in the README file in the above directory, which classifies the bursts by frequency and altitude.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Solar Radio Burst Event Summary Lists

Added in October 2001.
See About Radio Burst List (README2 file) for a description.

Solar Radio Spectrum

Level of Origin
Freq (MHz) Wavelength
--------------------------------------------------
Lower Chromosphere
15400 1.9 cm
8800 3.4 cm
--------------------------------------------------
Middle Chromosphere
4995 6.0 cm
2695 11.1 cm
--------------------------------------------------
Upper Chromosphere
1415 21.2 cm
610 49.2 cm
410 73.2 cm
--------------------------------------------------
Lower Corona
245 1.2 m
--------------------------------------------------
Upper Corona
75 to 25 4.0 m to 12.0 m
--------------------------------------------------

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

All indicators that 1147 is a very energetic region.

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[af4ex]

I said:
> Normally these bursts are much smaller,
> but this the biggest I've seen

Back on Nov 3 (page 21), the RF burst generated by AR1112/1121 (which was also rotating from the far side) was very big, but I think 1147 shows more energy, based on the illumination of the burst.
solarcycle24com.proboards.com/index.cgi?board=general&action=display&thread=1306&page=21

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[bradk]

I hope so, a nice interesting flare would be nice as the cycle has been, well, less than spectacular and only noteable for its lack...

[af4ex]

Overall it looks like SFI peaked yesterday and is starting to fall and the spots seem to be fading now.
Penticton
Date MHZ 1700Z 2000Z 2300Z
2011 Jan 12 2800 80 80 80
2011 Jan 13 2800 80 80 79
2011 Jan 14 2800 80 79 79
2011 Jan 15 2800 81 80 80
2011 Jan 16 2800 81 80 80
2011 Jan 17 2800 81 82 82
2011 Jan 18 2800 83 81 81




Is the show over? In any case AR1140 and that old area below it that was AR1112 back in Oct, are still looking active. But still more than a week away from rotating into view again.

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[bradk]

I deleted my post too, now back to regularly scheduled programming.

The backside looks no more active than the frontside, I am not sure your spike is coming af4ex.

[af4ex]

That area on the backside, north and south, has produced the largest sunspot (north) and the largest filament eruption (south) so far in SC24. So, if the big spike comes, I'm betting it will start in that area.

Mark my words (if i'm right).

:-]

[af4ex]

bradk
> The backside looks no more active than the frontside...

Take another look. That area looks a lot more active than the front side. Let's hope it can keep going another week or so.

We'll be seeing old 1141 rotating over in the next day or so. Not much activity there, at least not in EUV.

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[af4ex]

I just saw a 17Ghz flare in the region below 1147, which lasted about 20 minutes around 0000Z. Hasn't been reported by NOAA (but I think can see it in the x-ray plot a few minutes earlier).

Same region shows up in EUV and continuum too (green circles). I think. Would you all agree these are 3 views of the same region?

Also catching an EUV glimpse of the magnetic lines coming out of old 1141 on the east limb, still on the far side.

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[af4ex]

... from that same region, a C3.3 x-ray flare

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[bradk]

Interesting. Do flares often leave a magnetic signature of small "specks" afterwards?