Active Region 1996

[Marcel de Bont]

SpaceWeatherLive Report

Analysis M9.3 solar flare

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Sunspot region 1996 just produced an impulsive M9.3 (almost X-class) solar flare that peaked at 22:34 UTC. The flare was rather impulsive which likely means there will be no CME associated with the flare. Also, the location of the flare near the limb means any resulting CME is likely to miss Earth. A minor proton event could be possible because the eruption occurred near the west limb but this is unlikely.

http://www.spaceweatherlive.com/community/uploads/monthly_03_2014/post-94-0-06623100-1394664805.jpghttp://www.spaceweatherlive.com/community/uploads/monthly_03_2014/post-94-0-66110100-1394664891.png

A detailed analysis of this region is difficult because of it's location near the limb but it is possible that this region possesses a delta structure. More M-class flares are possible while it rotates on the limb but any eruptions are unlikely to affect Earth.

On this page an overview of the development of this region: http://www.spaceweatherlive.com/en/solar-activity/region/11996

[Guest doczax]

Hello,

 

    I've been watching Spaceweatherlive for several months.  I really enjoy all the real-time data and visualizations.  This is my first post.

 

    I've been wondering: what does it means for a flare to be impulsive?  How can you tell this flare was impulsive and how did you know so fast? 

 

Thanks!

[Marcel de Bont]

Hi doczax, welcome! Nice to hear you enjoy the site.

The difference between an impulsive flare and a long duration flare lies in how long the flux remains near it's peak value. Most solar flares rise rapidly and then either drop fast (impulsive) or slow (long duration). Another kind of long duration flares rise slowly and than drop slowly as well but they are more rare than fast rising flares.

I declared the flare as impulsive because it's strength declined rapidly from M9 at 22:35 UTC to already M7 at 22:36 UTC etc. A long duration flare would have likely showed more readings in the M9 or M8 range as it peaked and then more slowly drop. There are flares that are much more impulsive then this but it was still fairly short in duration.

The X4.9 from last month was a great example of a long duration flare: '?do=embed' frameborder='0' data-embedContent>>

Impulsive:

Long duration:

Hope this answers your question.

[Guest doczax]

Thanks so much. It is really clear looking at those two xRay flux charts, is there a range where it's harder to tell?  As in, is it a judgement call looking at the charts, or is there a mathematical cutoff? Something like: if the xRay flux is dropping >5% per minute after the flare peak it is short duration therefore impulsive?

 

doczax

[Marcel de Bont]

It's a judgement call, there is no set cutoff or anything as to when it is a long duration flare or when it's impulsive as far as I am aware. I often look at how the flare peaks, is it a sharp peak with a fast drop of or does the flare hang around for a while near it's peak value. Does it drop fast after the peak or very slowly? You can recognize the different flare patterns after a while and judge. This is also important to determine if the flare is likely to produce a CME or not.