Flares Without Sunspots

[Solsearcher]

From all indications, the sun appears to be emerging from an Epic-Grand Solar Minimum due to the hyperbolic approach of UNPRECEDENTED Comet C/2017 K2 (Panstarrs). A possible explanation for the anomalous (UNPRECEDENTED) solar flaring without sunspots may be that Comet K2 is disturbing the sun's equilibrium externally, as opposed to internally. Normal solar flaring does indeed begin with the appearance of an aperture in the photosphere (sunspot). Bear in mind that current solar dynamic theory remains just that....theory, and is therefore by definition of terms...not absolute. Reality, in the end, is the domain of the perspicuous and not the dogmatic.  Comet Panstarrs K2 – Research and Mission Control Center (comet-k2.com)

Sit down before fact as a little child, be prepared to give up every preconceived  notion, follow humbly wherever and to whatever abyss nature leads, or you shall learn nothing.

Thomas Huxley

[Isatsuki San]

7 hours ago, Solsearcher said:

From all indications, the sun appears to be emerging from an Epic-Grand Solar Minimum due to the hyperbolic approach of UNPRECEDENTED Comet C/2017 K2 (Panstarrs). A possible explanation for the anomalous (UNPRECEDENTED) solar flaring without sunspots may be that Comet K2 is disturbing the sun's equilibrium externally, as opposed to internally. Normal solar flaring does indeed begin with the appearance of an aperture in the photosphere (sunspot). Bear in mind that current solar dynamic theory remains just that....theory, and is therefore by definition of terms...not absolute. Reality, in the end, is the domain of the perspicuous and not the dogmatic.  Comet Panstarrs K2 – Research and Mission Control Center (comet-k2.com)

Sit down before fact as a little child, be prepared to give up every preconceived  notion, follow humbly wherever and to whatever abyss nature leads, or you shall learn nothing.

Thomas Huxley

hey Solsearcher, there is no great solar minimum, the sun continues to advance its activity as we approach solar maximum, there were even 6 sunspots in front of the earth the other week, so the comet 2017 k2, had nothing to do

[helios]

@Solsearcher
It was a typical/normal solar minimum. Which "anomalous" flare do you refer to? There was no "UNPRECEDENTED" flare.
C/2017 K2 has certainly nothing to do with current solar activity.

 

[Newbie]

Solsearcher: a few observations.

The minor flares that have occurred recently where there doesn't appear to be a sunspot, are nothing out of the ordinary. Certain activity in the photosphere can produce erupting filaments: arcs of plasma, or sigmoids, where it is proposed that ropes of electric current twist and break and reconnect. Both events are capable of producing minor flares in the absence of 'observable' sunspots.

Solar dynamic theory may be a theory but it is a good fit for many, many scientific observations. 

To attribute this minor solar activity to a Comet? Really?

Newbie

 

Edited August 4, 2021 by Newbie

[Drax Spacex]

Revisiting the question posed in the first post:  "For all C-class or higher flares, what percent occurred in plage-only areas on the solar disk?".

We have seen 1 C flare in a plage-only out of a total of 30 C or higher flares since June 24, 2021.  The current running average then estimates that 3.3% of all C-class or higher flares occur in plage-only areas (noting the 1 C flare occurred from a plage area containing a sigmoid).

[helios]

@Drax Spacex 

I assume you mean the B9.8 flare on 2021-Jul-27 22:26 UT. I had a closer look and I see small spots during the flare. Although the region counted as plage.

https://streamable.com/4tz1z9

This is an overlay of AIA94 and HMI continuum. Small spots can be seen top right and bottom left of the flare. Those spots are very short-lived

[Drax Spacex]

Yes - that's the one - a nice video merge.  I do see those spots, but are they sunspots or pores?  I do not know the size threshold above which a pore is considered a sunspot.  There was no active region defined here on July 27.  But as you say, they may have briefly qualified to be sunspots just before the flare but not in the quantized observation periods when the synoptic maps were made.

[helios]

Yes they might have been pores. It is the maximum available resolution of the imagery, zooming in doesn't make it better.
I've added a magnetogram layer:
https://streamable.com/zxu9jp
It seems that the flare is occurring between a group of negative and a group of positive pores.

Edit:
"Sunspots and pores are distinguished simply by the presence of a penumbra: Sunspots have a penumbra while pores do not." (Source)
So the resolution does not allow to distinguish whether they are pores or spots .

The larger ones seem to be having a diameter of ~2.4 Mm

So likely a pore.

Edited August 5, 2021 by helios

[Newbie]

Drax Spacex: A zombie flare -  B5.4, from zombie plage - 2850, so close to the limb as well.

Newbie

[helios]

Looks like the B5.4 happened behind the limb, so it could have been a C-flare.

https://streamable.com/b7o3qt

But it's not determinable if the region had spots.

[Newbie]

40 minutes ago, helios said:

Looks like the B5.4 happened behind the limb, so it could have been a C-flare.

https://streamable.com/b7o3qt

But it's not determinable if the region had spots.

Quite impressive flare actually from that pic.   I checked its Location: S28, W86 degrees, so close to the limb! It was attributed to AR2850 which had been downgraded to plage. There may have been some pores

We'll never know 😄

Actually, the table you posted giving parameters for sunspots and pores was interesting. In addition, sunspots have well defined edges whereas pores have indistinct edges.

[helios]

SDOs resolution is not high enough to clearly determine the shape of the pores in the case of the B9.8 flare.
But from the size and their short life, I assume they were pores.

I found this image of unknown source, where pores can have a relatively well defined border:

 

Today at midnight UTC there was a C1.4 flare. At that time, the region only had a small pore or spot. But it seems to be rapidly developing since.
Unfortunately there is a problem with SDO/HMI data on jhelioviewer, but here's the available AIA-94 and HMI-overlay at this time:
https://streamable.com/u9ylp1

[Newbie]

Hi Helios: Good diagram! Some of those pores could be spots because they exhibit the faintest penumbra when sufficiently enlarged. Yeah that's the problem with the resolution of SDO images, pores show up on SDO as ill-defined brown freckles (for want of a better word) whereas spots have those well defined dark cores.

I was surprised to see that C1.4 flare erupt from the region around 2853, I thought it was another zombie plage area. Looking at that video though It looks like it flared then produced a sunspot in the aftermath. Interesting stuff. 

There may be a determinant, a threshold to cross, before a pore grows into a fully fledged sunspot, while other pores stay pores until they fade away. 

Newbie

Edited August 9, 2021 by Newbie

[Drax Spacex]

There has been some historical disagreement around the physical distinctions and even semantics of "pore" and "sunspot".  Such as, is a pore a type of sunspot, or is a pore not a sunspot?

From the pdf presentation with link below, there are 3 slides starting at page 33 (of course) that review various definitions and distinctions between pores and sunspots, with examples.

From this, they minimally agree in semantics that a pore is not a sunspot, and regarding diameter size in arcseconds a pore<3" while a sunspot>3".

https://www.swpc.noaa.gov/sites/default/files/images/u33/Clette_SSNreview_1.pdf

[Newbie]

Emerging magnetic flux (movement of a magnetic field through an area) is the forerunner to active regions developing in the photosphere. Sunspot development is dependent on the strength of the magnetic flux. Active regions can produce sunspots which develop very quickly when the magnetic flux is high. When active regions decay the sunspots disappear leaving faculae, plages, and possibly pores. Sometimes there are regions of lower magnetic flux that might appear active yet don't produce any sunspots. They are usually called plages and may have pores. Filaments and sigmoids that occur around active regions at times can be responsible for minor flares.

Major flares occur when magnetic flux is high from spotted active regions.

Drax Spacex: I see your point about semantics and minimally agreeing. Not all pores and sunspots are created equal. In my humble opinion I don't think it matters if agreement can't be reached on a definition of each. If I see a dark speck on the Suns surface I call it a sunspot, if I see a brown freckle it's a pore.

All fun stuff!

Newbie

Edited August 9, 2021 by Newbie
Spelling of course

[helios]

So, what criteria shall we use as a definition of sunspot in flares without sunspots?

I would suggest "no visible darkening of the photosphere"

[Newbie]

Helios: Looking again at that pic you posted I would say those smaller dark spots were areas of emerging flux and I think SWPC would include them in the sunspot number for that active region. What do you think?

I can't usually see all the sunspots that SWPC numbers for AR's anyway. I'm always surprised how many they come up with.

Another aspect of what determines a sunspot is addressed in the article that Drax Spacex posted. A sunspot, or group of sunspots has to be visible for a certain length of time before it is numbered.

Yeah the answer to the question Drax Spacex posed: Flares without Sunspots! I think we can call them zombies!

What is a sunspot? For me, it's an area on the photosphere that has a dark core surrounded by a lighter penumbra. It's darker because it is of a lower temperature than its surroundings.

What is a zombie sunspot?  No visible darkening of the photosphere, but can produce minor flares. I like it. 

[Drax Spacex]

9 hours ago, helios said:

So, what criteria shall we use as a definition of sunspot in flares without sunspots?

I would suggest "no visible darkening of the photosphere"

Well that's a good point.  The simple method I presumed to use is:  For each C flare or higher, was there an AR defined at that location in the most recent Synoptic map?  If not, then it is a "flare without sunspots."

A better method would be to do what you have been doing.  For each C flare or higher in a location without an AR defined, review the HMI imagery at the start of the flare to check for any sunspots (using some consistent manual or even automated method for determining what is a sunspot).

[Newbie]

 

On 8/10/2021 at 7:07 AM, Drax Spacex said:

For each C flare or higher, was there an AR defined at that location in the most recent Synoptic map?  

I know this topic began after a B9.8 flare erupted from a plage area a month or so ago. How often has the spotless Sun produced M or X flares though? Yet the chance of a C, M or X flare occuring when the Sun has no AR's is never 0%. SWPC always attribute a 1% chance that the Sun will produce one such flare.

There was a beta-gamma-delta group a few weeks ago, which produced only minor flares yet we've seen impulsive M and X flares that weren't expected from the AR's that produced them.

The Sun is unpredictable....

......so we continue to pore over (excuse the pun) the HMI imagery looking for the source of that unexpected flare, because that is what we do.

Edited August 11, 2021 by Newbie
Punctuation of course

[MinYoongi]

 

 

Saw this today on https://www.spaceweather.com/ 🥰 Thought about this Thread immediatly!

[Drax Spacex]

C1.5 impulsive flare today from plage area (2853).  That makes 2 C flares from this area in the past week while no AR was defined for it.

Perhaps its time to consider assigning flare probabilities to plage areas.  Or, less formally, to account for them with a discretionary marginal increase in the whole solar disk flare probabilities.

Edited August 13, 2021 by Drax Spacex
probabilities

[Newbie]

 

 

 

 

3 hours ago, Drax Spacex said:

C1.5 impulsive flare today from plage area (2853).  That makes 2 C flares from this area in the past week while no AR was defined for it.

Perhaps its time to consider assigning flare probabilities to plage areas.  Or, less formally, to account for them with a discretionary marginal increase in the whole solar disk flare probabilities.

 

Hi Drax Spacex: There is obviously still a lot of activity around this plage area.  

The last four flares detected were from areas close to old AR2853, (according to SolarSoft). B1.2, A7.9, A8.2 and C1.4.

There was also sigmoid activity at numerous times. 

At the moment the probability for a C flare is listed at 5%, perhaps this is allowing for AR2855 which has almost decayed.

It would be really hard to predict flaring from a plage area; how low do you go? 0.5%? Less?

A low C flare is most often a low class flare with high background Solar Flux. When I looked at the HMI imagery of AR2853 this morning there seemed to be more magnetic loops coming from that area.

By the way, I didn't bother looking at solar stuff to begin with as there has been so little activity lately, then I saw your post about the C flare. Thanks for that. 😃

[helios]

11 hours ago, Drax Spacex said:

C1.5 impulsive flare today from plage area (2853). 

The part of the region where the flare happened seems to be also mostly pore-free. Or perhaps very small ones.
https://streamable.com/aquzjy

[Drax Spacex]

On 8/13/2021 at 8:22 PM, Newbie said:

It would be really hard to predict flaring from a plage area; how low do you go? 0.5%? Less?

A low C flare is most often a low class flare with high background Solar Flux. When I looked at the HMI imagery of AR2853 this morning there seemed to be more magnetic loops coming from that area.

 😃

We've seen 3 C flares in 52 days from plage areas, so I'd say 5% or 5/1/1/1.  Could be higher or lower based on analyst discretion accounting for plage size, activity, magnetic configuration, presence of sigmoid, etc.

In a few years time when the background solar flux frequently approaches or exceeds C level, these low level C flares could be lost in the noise, at least in the X-Ray flux graph - though they may still be visible in imagery.

I'd imagine you could get a large number of hysteresis-induced C-flares tagged in the data when the background flux is vacillating about the minimim C level without an additional signal-to-noise threshold to distinguish between a flare and just fluctuating flux.

[Newbie]

13 hours ago, Drax Spacex said:

We've seen 3 C flares in 52 days from plage areas, so I'd say 5% or 

I'd imagine you could get a large number of hysteresis-induced C-flares tagged in the data when the background flux is vacillating about the minimim C level without an additional signal-to-noise threshold to distinguish between a flare and just fluctuating flux.

Yes I agree. it's probably only when we have such low solar activity, such as is the case now, that we observe 'C' flares coming out of nowhere, so to speak. When background flux is C level, there are usually a number of AR's flaring regularly so the contribution of plage areas would mostly go unnoticed. 

Consider AR 2853. Although it has been mostly spotless in its traverse across the sun it has been the cause of higher background Solar Flux. In HMI imagery it is still very bright, with many magnetic loops. Much brighter than the output from 2857 which has a few, albeit tiny, spots. 

I read today where there was an eruption on the far side of the Sun (of course it's on the far side!), with a big CME released, not earth directed obviously. Hopefully we might see some action by the end of the week.

Three C flares in 52 days from virtually plage areas - not bad!