A Record-Setting CMEless Flare
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|title = A Record-setting CMEless Flare | |title = A Record-setting CMEless Flare | ||
|first_author = Sam Freeland | |first_author = Sam Freeland | ||
- | |second_author = | + | |second_author = Greg Slater |
|publish_date = October 27, 2014 | |publish_date = October 27, 2014 | ||
|previous_nugget =[http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/The_Formation_of_Kappa_Distributions_in_Solar_Flares Kappa distributions] | |previous_nugget =[http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/The_Formation_of_Kappa_Distributions_in_Solar_Flares Kappa distributions] | ||
- | |next_nugget = | + | |next_nugget = [[Back from the Far Side]] |
|number = 239 | |number = 239 | ||
}} | }} | ||
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A flare is essentially a radiative process, but the physics closely involves | A flare is essentially a radiative process, but the physics closely involves | ||
mass motions and dynamical effects. | mass motions and dynamical effects. | ||
- | Contrariwise a CME | + | Contrariwise a [http://en.wikipedia.org/wiki/Coronal_mass_ejection CME] |
+ | is mainly dynamical, but of course if it did not radiate detectably | ||
we would not be able to observe it very well. | we would not be able to observe it very well. | ||
- | The standard flare model ("CSHKP", the subject of several Nuggets) expressly | + | The standard flare model |
+ | ([https://www.google.com/images?client=safari&rls=en&q=cshkp+model&oe=UTF-8&gws_rd=ssl&hl=en&sa=X&oi=image_result_group&ei=4ldOVIawJ4ukyQSxjYKQCA&ved=0CCEQsAQ "CSHKP"], | ||
+ | the subject of several Nuggets) expressly | ||
assumes that a CME be present, but most flares do not have CME associations | assumes that a CME be present, but most flares do not have CME associations | ||
and so this idea needs generalization. | and so this idea needs generalization. | ||
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occurrence becomes. | occurrence becomes. | ||
- | The hot news this week is that AR | + | The hot news this week is that AR 2192, which features the huge naked-eye |
sunspot group pictured in Figure 1, has hosted many powerful flares and | sunspot group pictured in Figure 1, has hosted many powerful flares and | ||
no CMEs. | no CMEs. | ||
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with the major group responsible for some of the "Halloween flares" of 2003. | with the major group responsible for some of the "Halloween flares" of 2003. | ||
- | [[File:239f2.png| | + | [[File:239f2.png|600px|thumb|center|Fig. 2: |
- | Left: Development of spot area in the current region, AR | + | Left: Development of spot area in the current region, AR 2192, |
compared with that of the second-biggest during the RHESSI era. | compared with that of the second-biggest during the RHESSI era. | ||
The fact that it's exactly 11 years later is a coincidence; the fact that | The fact that it's exactly 11 years later is a coincidence; the fact that | ||
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have come from far around on the invisible hemisphere of the Sun, and | have come from far around on the invisible hemisphere of the Sun, and | ||
thus had a true magnitude larger than what the GOES plot shows. | thus had a true magnitude larger than what the GOES plot shows. | ||
+ | This event was definitely eruptive; see the SDO | ||
+ | [http://sdowww.lmsal.com/sdomedia/h264/2014/10/14/SSW_cutout_20141014T1816-20141014T2000_AIA_131-193-171_S12E88.mov composite movie]. | ||
]] | ]] | ||
The flares have been remarkable, especially in their total ignorance | The flares have been remarkable, especially in their total ignorance | ||
- | of CME formation. | + | of CME formation (except for |
- | To what extent do flares like this resemble the standard model, most | + | [http://sdowww.lmsal.com/sdomedia/h264/2014/10/14/SSW_cutout_20141014T1816-20141014T2000_AIA_131-193-171_S12E88.mov SOL2014-10-14]). |
+ | To what extent do the CMEless flares like this resemble the standard model, most | ||
recently discussed in Nugget No. [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/The_3D_standard_model_for_eruptive_flares 226]? | recently discussed in Nugget No. [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/The_3D_standard_model_for_eruptive_flares 226]? | ||
Figure 3 shows an overlay of the flare ribbons from SOL2014-10-24 on | Figure 3 shows an overlay of the flare ribbons from SOL2014-10-24 on | ||
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Most of the features of such a model - current sheet, cusp, plasmoid eruption, | Most of the features of such a model - current sheet, cusp, plasmoid eruption, | ||
opening magnetic fields, fast and slow shock waves, above-the-loop-top | opening magnetic fields, fast and slow shock waves, above-the-loop-top | ||
- | sources, downflows, magnetic reconnection - simply don't appear here even | + | sources, downflows, magnetic reconnection in a detectable large-scale |
+ | current sheet - simply don't appear here even | ||
though the flare has GOES magnitude X3.1. | though the flare has GOES magnitude X3.1. | ||
This hints strongly that most of these features can arise from a different | This hints strongly that most of these features can arise from a different | ||
global model. | global model. | ||
We note also that this region, at the time of writing, had produced not only the | We note also that this region, at the time of writing, had produced not only the | ||
- | one, but at least | + | one, but at least five other X-class flares, none of which involved CMEs or SEPs. |
== Conclusions == | == Conclusions == | ||
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This Nugget reports a hot topic, and at the time of publication the events | This Nugget reports a hot topic, and at the time of publication the events | ||
are still developing. | are still developing. | ||
- | Active region | + | Active region 2192 has already set new standards, though: the biggest spot |
group since RHESSI was launched (and a nice coincidence of a naked-eye group | group since RHESSI was launched (and a nice coincidence of a naked-eye group | ||
and a partial eclipse observable from the Bay Area), and a record-setting | and a partial eclipse observable from the Bay Area), and a record-setting | ||
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== References == | == References == | ||
- | [1] [http://adsabs.harvard.edu/abs/2004JGRA..109.7105Y A catalog of white light coronal mass ejections observed by the SOHO spacecraft] | + | [1] [http://adsabs.harvard.edu/abs/2004JGRA..109.7105Y "A catalog of white light coronal mass ejections observed by the SOHO spacecraft"] |
Latest revision as of 15:28, 8 August 2015
Nugget | |
---|---|
Number: | 239 |
1st Author: | Sam Freeland |
2nd Author: | Greg Slater |
Published: | October 27, 2014 |
Next Nugget: | Back from the Far Side |
Previous Nugget: | Kappa distributions |
List all |
Contents |
Introduction
Flares (in the lower solar atmosphere) and coronal mass ejections (in the corona) have a complicated interrelationship that we have not quite fathomed yet. A flare is essentially a radiative process, but the physics closely involves mass motions and dynamical effects. Contrariwise a CME is mainly dynamical, but of course if it did not radiate detectably we would not be able to observe it very well. The standard flare model ("CSHKP", the subject of several Nuggets) expressly assumes that a CME be present, but most flares do not have CME associations and so this idea needs generalization. Ref. [1] describes how the more powerful the flare, the more likely a CME occurrence becomes.
The hot news this week is that AR 2192, which features the huge naked-eye sunspot group pictured in Figure 1, has hosted many powerful flares and no CMEs. This region produced the event SOL2014-10-24T21:41 (X3.1), which so far as we know has set a record in flare energy for a CMEless event. At S16W20, the flare was ideally situated to produce a halo CME event, Earthward-directed and possibly geoeffective, and to spew solar cosmic rays in all directions. None of this happened, so this Nugget will explore the situation a bit.
Region and Flare
As Figure 1 illustrates, several things came together with this late major sunspot region. By a small amount, its area exceeded the previous maximum since the launch of RHESSI. Figure 2 shows the development of the sunspot region's area, in comparison with the major group responsible for some of the "Halloween flares" of 2003.
The flares have been remarkable, especially in their total ignorance of CME formation (except for SOL2014-10-14). To what extent do the CMEless flares like this resemble the standard model, most recently discussed in Nugget No. 226? Figure 3 shows an overlay of the flare ribbons from SOL2014-10-24 on an HMI magnetogram. The ribbons and other elements of the flare morphology look normal, with the only obvious distinction being the absence of the eruption and the CME.
Most of the features of such a model - current sheet, cusp, plasmoid eruption, opening magnetic fields, fast and slow shock waves, above-the-loop-top sources, downflows, magnetic reconnection in a detectable large-scale current sheet - simply don't appear here even though the flare has GOES magnitude X3.1. This hints strongly that most of these features can arise from a different global model. We note also that this region, at the time of writing, had produced not only the one, but at least five other X-class flares, none of which involved CMEs or SEPs.
Conclusions
This Nugget reports a hot topic, and at the time of publication the events are still developing. Active region 2192 has already set new standards, though: the biggest spot group since RHESSI was launched (and a nice coincidence of a naked-eye group and a partial eclipse observable from the Bay Area), and a record-setting major CMEless flare. We think that this occurrence seriously challenges standard flare models and expect that the phenomena introduced here will elicit lots of research activity.
References
[1] "A catalog of white light coronal mass ejections observed by the SOHO spacecraft"
RHESSI Nugget Date | 27 October 2014 + |
RHESSI Nugget First Author | Sam Freeland + |
RHESSI Nugget Index | 239 + |
RHESSI Nugget Second Author | Greg Slater + |