Let’s Play a Game -> show me the deltas!

[WildWill]

23 hours ago, arjemma said:

It was suggested that I post the images of the delta of AR3213 that emerged on February 7 2023. This is how small they can be so it's a fairly good example.

 

I asked her to post this here as I think it really shows a classic “textbook” delta spot.  It’s very clearly a spot (albeit small) inside the penumbra of another spot of opposite polarity. 
 

It was also a really nice catch! Thank ya for sharing this with us!

Will

[Philalethes]

3 hours ago, WildWill said:

inside the penumbra of another spot of opposite polarity

Well, technically speaking it does have its own penumbra, as all spots do, but the nearby negative penumbrae encroaching so closely upon it makes it seem like it's "inside" their shared penumbra.

If you look at e.g. 3217 currently, you can see a delta where this isn't the case, i.e. where you can see the penumbra of each spot more clearly on the m-gram, but see that the spots are still inside the same penumbra as viewed on the i-gram:

You could also make the case that their penumbrae are connected to the larger spot on the bottom, but you can make out a vague line of separation there, so that's a bit more tenuous.

[WildWill]

17 hours ago, Philalethes Bythos said:

Well, technically speaking it does have its own penumbra, as all spots do, but the nearby negative penumbrae encroaching so closely upon it makes it seem like it's "inside" their shared penumbra.

If you look at e.g. 3217 currently, you can see a delta where this isn't the case, i.e. where you can see the penumbra of each spot more clearly on the m-gram, but see that the spots are still inside the same penumbra as viewed on the i-gram:

You could also make the case that their penumbrae are connected to the larger spot on the bottom, but you can make out a vague line of separation there, so that's a bit more tenuous.

Howdy PB and All Y’all! 

To me and my untrained inexperienced eyes, I see two totally different situations here. 

In 3217, at the time of your posting, I don’t see a delta. I see two spots getting pushed together. I can see very clearly that they both have their own penumbras. I can draw a nice simple line between the polarities.

I also disagree with your assertion that all spots have their own penumbra. I’ve seen lots of spots with no penumbra (not necessarily deltas). The definition I have read over and over again is “two or more spots of different polarity sharing a single penumbra”.  That’s what makes it a delta - it is inside the penumbra of another spot of different polarity. 

Whereas in the example that @arjemma posted, we see a nice round penumbra enclosing three spots, the delta is clear - at least to me.

Your “example” reminds me of AR13089, from the end of August, everyone called it a big delta- but I couldn’t see it. I went back and reviewed the first page of this thread and I still believe that AR13089 didn’t have a delta at that time. I believe it did develop deltas as it went around the limb a week later.

The overlays that you like to like to use are not quite the tool you make it out to be. Solar astronomers have been classifying delta spots for some time before the advent of colorized magnetograms and computer graphics period. I understand that the Air Force, where much of the analysis originates, still follows the same process and manual for identifying deltas and classifying spots that they did 30 years ago. Long before SOHO, SDO or serious computing power as compared to today. 

The other thing about those overlays is that the images were taken with different imaging systems for different purposes. I believe the Intensitygram (white light) is labeled “flattened”.  I would guess to reduce spherical aberration. 

The colorized magnetogram is never going to line up exactly with the Intensitygram except at center sun. The farther you move from the center of the sun, the less they are going to align exactly. Another BIG consideration with the colorized magnetogram is that it is not necessarily showing you the “same things” in terms of features. The colorized magnetogram is gonna pick up on any ionized plasma - it doesn’t necessarily have to be on the photosphere. It can be a plume or filament which is in the chromosphere. I took me a while to realize this.  I noticed arcs on magnetically active plasma and couldn’t figure out what (where) they were on the Intensitygram. Then one day staring at filaments on the sun, it hit me - those features on the magnetogram are not on the surface. 

I’ll iterate, the example posted by @arjemma appears to be a “textbook” example, albeit small, of a delta spot - according to all the textbooks/sources I’ve been able to find. 

The other thing I look at if it’s not clear to me is what the AR is doing. If it’s all quiet - then it doesn’t really matter to me whether it’s really a “delta” or not - cause it don’t matter a lick ta me if’n it ain’t doin nuthin! I would refer you to the discussion around AR13089 at the beginning of this thread again. I’ve an image three where I have drawn a “simple” line (continuous and piecewise differentiable) between the spots. Just because they are getting pushed together does not make a delta. That is one way which deltas can form according to what I’ve read, but it’s not a delta until one is absorbed by the others penumbra.

The colorized magnetograms are really cool, but ya gotta sit back and also consider their limitations. I think once you move 60* from the meridian, it loses a great deal of weight in my view because of the angle. At 60*, you’re looking through a whole lot of chromosphere before you get to the “surface” (photosphere). This can cause magnetized plasma in the chromosphere to appear on the surface tens of thousands of miles from the features for the photosphere which appear right next to it… I hope that makes sense to y’all. 

I started this thread back in August, so that I could learn more about identifying deltas. The most significant thing I’ve learned since then about identifying deltas is that it is an art form.  We very seldom see the “classic textbook” delta. So, it’s not always easy nor will everyone - including seasoned experts - always agree. I’ve read and reviewed everything I could find about classifying deltas in the last six months or so. Still, it is an art form and I am an analytical kinda guy… 

We can agree to disagree, but I don’t see the delta in your image (which I think we agree upon). And as I pointed out earlier in my post, my understanding is that even seasoned “experts” do not always agree on classification. 

AND… If’n it ain’t kickin’ ‘em out, it don’t really matter to me anyway, no action, no point…

Gig’em!

Will

Edited February 11, 2023 by WildWill

[Philalethes]

9 minutes ago, WildWill said:

In 3217, at the time of your posting, I don’t see a delta. I see two spots getting pushed together.

Well, as explained earlier and previously, that's exactly what a delta is: two spots of opposite polarity being pushed together sufficiently for their penumbrae to appear as one. It's just that in the cases you think of as deltas, the smaller region is so surrounded by the opposite penumbra that you don't see its own very well. That doesn't mean the cases where you can see the different polarities of the penumbrae being joined more clearly are not deltas.

The region even got designated as being a delta too shortly after I posted that. Now it's broken apart a bit, and the penumbrae are no longer connected to the point where they appear as a single penumbra on the i-gram. And if by "kicking them out" you mean CMEs, then that's a different criterion, but 3217 has been flaring a lot, even if the activity hasn't been that eruptive (it did have some nice eruptions as it was still beyond the limb, though). It even just had a very impulsive X-flare.

Edited February 11, 2023 by Philalethes Bythos

[WildWill]

3 minutes ago, Philalethes Bythos said:

Well, as explained earlier and previously, that's exactly what a delta is: two spots of opposite polarity being pushed together sufficiently for their penumbrae to appear as one. It's just that in the cases you think of as deltas, the smaller region is so surrounded by the opposite penumbra that you don't see its own very well. That doesn't mean the cases where you can see the different polarities of the penumbrae being joined more clearly are not deltas.

The region even got designated as being a delta too shortly after I posted that. Now it's broken apart a bit, and the penumbrae are no longer connected to the point where they appear as a single penumbra on the i-gram. And if by "kicking them out" you mean CMEs, then that's a different criterion, but 3217 has been flaring a lot, even if the activity has been that eruptive (it did have some nice eruptions as it was still beyond the limb, though). It even just had a very impulsive X-flare.

I think we’ll end up having to agree to disagree on this one. 
 

According to my “textbooks”, deltas form three ways:

1 - They can pop up already formed. A pair of spots with opposite polarity pop up to the surface within a single penumbra.

2 - A spot of opposite polarity can form within the penumbra of a spot of opposite polarity.

3 - Two spots can be “pushed together” until one is absorbed into the penumbra of the other. This doesn’t mean that just because two spots are being pushed together so that their penumbras touch that you have a delta. They must be within 2* (two degrees, I’ve also seen 2 1/2 degrees used) of each other and you cannot draw a simple line between polarities - simple line as defined previously. Same definition of “simple line” as is used to distinguish a beta from beta-gamma.

You’ve asserted that number 3 above is the only way in which deltas can form. I do not agree. 

Hope this helps!

Will

PS “kickin it” refers to flaring/flux… 

PPS It is a really good, clear example that she posted in my view. I think people get too wrapped up in the colorized magnetograms. If’n ya are gonna place that much weight on them, at least download the quality data for your analysis. As @mozy learned from the SDO project team is that the images you see on the website are “not scientific quality data”. Not ready for prime time. 
 

Well, the earth weatherman was wrong again! You’d think they would’ve figured this simple system out by now… I’ve got clear skies out this morning - gotta go, gotta go!
 

Y’all have fun! I will!

[Sam Warfel]

There is some gray area and ambiguity between “merged penumbrae” shoved together, and a delta spot. I always thought a delta, or at least a strong delta, was an umbra completely surrounded by a penumbra of a different polarity, belonging to a different spot. For example, a small positive umbra is a delta spot surrounded by negative penumbra belonging to the large negative umbra spot nearby.
However, that’s just an idea I had, I am by no means an expert. Is that kind of what you were thinking, @Philalethes Bythos?

I suggest we find a professional scientist to consult on this, I bet we know some. @WildWill, can you provide the sources to your textbook definitions? Thanks!

Edited February 11, 2023 by Sam Warfel

[Philalethes]

Just now, Sam Warfel said:

I always thought a delta, or at least a strong delta, was an umbra completely surrounded by a penumbra of a different polarity, belonging to a different spot.

There are numerous textbook examples showing clearly that this is not true, and I've even outlined such examples previously. Two spots existing side-by-side, each with their own clearly visible penumbrae as viewed on any magnetogram (colorized or not, not relevant at all; the misleading assertions WildWill makes about how I'm using these makes it clear that he doesn't understand what they're used for at all in this context), can still form a delta as long as their penumbrae are close enough together to be shared, i.e. to have "merged", it's not necessary at all for one of the spots and its surrounding penumbra to completely engulf the other as WildWill seems to think must be the case.

[Sam Warfel]

1 minute ago, Philalethes Bythos said:

Two spots existing side-by-side, each with their own clearly visible penumbrae as viewed on any magnetogram (colorized or not, not relevant at all; the misleading assertions WildWill makes about how I'm using these makes it clear that he doesn't understand what they're used for at all in this context), can still form a delta as long as their penumbrae are close enough together to be shared, i.e. to have "merged"

Isn’t that Will’s definition number 3 above?

Have you read any definitions pertaining to degrees of separation, like Will is citing?

[WildWill]

3 minutes ago, Sam Warfel said:

There is some gray area and ambiguity between “merged penumbrae” shoved together, and a delta spot. I always thought a delta, or at least a strong delta, was an umbra completely surrounded by a penumbra of a different polarity, belonging to a different spot. For example, a small positive umbra is a delta spot surrounded by negative penumbra belonging to the large negative umbra spot nearby.
However, that’s just an idea I had, I am by no means an expert. Is that kind of what you were thinking, @Philalethes Bythos?

I suggest we find a professional scientist to consult on this, I bet we know some. @WildWill, can you provide the sources to your textbook definitions? Thanks!

That’s what I was thinking. I can post some other sources, but the first one is the help and FAQ on “Space Weather Live”. You will find the same definitions there and the three ways in which delays form. There is also a nice section in the help on Daystarfilters.com. Nice pictures too. 
 

Ive was hoping for a professional to consult on some of the “deltas” shown in the last six months, but I learned that even the experts don’t always agree - they may agree on paper, but when it comes to pictures, they see different things - hence, art form. 

[Philalethes]

2 minutes ago, Sam Warfel said:

Isn’t that Will’s definition number 3 above?

Those three examples he repeats over and over just refer to three different ways deltas can form. All three are indeed possible, no one is disputing that. What he proceeds to add to that third way of forming is that one of the spots has to be "absorbed" into the other; this is derived from his own imagination, and not from how deltas are actually classified.

Also, even in the cases of 1 and 2, everything I've said still applies, the type of deltas I'm talking about can form in all three ways, so that's just yet another totally misleading statement and complete mischaracterization of what I'm saying.

5 minutes ago, Sam Warfel said:

Have you read any definitions pertaining to degrees of separation, like Will is citing?

Yes, that's typically also included as a criterion, i.e. a maximal degree of separation between the spots of 2 or 2.5 degrees. That's a perfectly fine and valid criterion, but not actually relevant to what's being talked about here at all, all the spots I've mentioned are well within that range. I even pointed to the very example used on this site itself on page 1, showing two different types of deltas, one where a large spot clearly retains a significant penumbra around it even if "surrounded" or "engulfed", and another where spots are much more "side-by-side".

[Sam Warfel]

6 minutes ago, WildWill said:

That’s what I was thinking. I can post some other sources, but the first one is the help and FAQ on “Space Weather Live”. You will find the same definitions there and the three ways in which delays form. There is also a nice section in the help on Daystarfilters.com. Nice pictures too. 
 

Ive was hoping for a professional to consult on some of the “deltas” shown in the last six months, but I learned that even the experts don’t always agree - they may agree on paper, but when it comes to pictures, they see different things - hence, art form. 

If even the scientists don’t have a one-size-fits-all definition, I doubt we’ll be able to come up with one either. 

The sun can be pretty messy sometimes, and resists our efforts to classify things into neat little boxes! A recurring problem throughout the history of science. 

[WildWill]

4 minutes ago, Philalethes Bythos said:

There are numerous textbook examples showing clearly that this is not true, and I've even outlined such examples previously. Two spots existing side-by-side, each with their own clearly visible penumbrae as viewed on any magnetogram (colorized or not, not relevant at all; the misleading assertions WildWill makes about how I'm using these makes it clear that he doesn't understand what they're used for at all in this context), can still form a delta as long as their penumbrae are close enough together to be shared, i.e. to have "merged", it's not necessary at all for one of the spots and its surrounding penumbra to completely engulf the other as WildWill seems to think must be the case.

I must not have communicated my thoughts properly. Because it’s obvious that you didn’t understand my assertions. You did get one right - it’s not a delta unless they have merged to where a spot and it’s penumbra have enclosed, engulfed, surrounded, whatever synonym ya like here…, another spot of opposite polarity and the center of the spots must be within 2 degrees of each other.
 

Im gonna leave it there as we are not going to agree on this. That’s ok, if everyone agreed, it would be awfully boring around here. But, at some point ya gotta say - we ain’t gonna agree and that’s it! I don’t see much point in beating a dead horse - it ain’t gonna get the field plowed…

Im there! Have ya a great day (and I mean that… have ya a great day). I’m done. 
 

Will

[Sam Warfel]

1 minute ago, Philalethes Bythos said:

Those three examples he repeats over and over just refer to three different ways deltas can form. All three are indeed possible, no one is disputing that. What he proceeds to add to that third way of forming is that one of the spots has to be "absorbed" into the other; this is derived from his own imagination, and not from how deltas are actually classified.

Also, even in the cases of 1 and 2, everything I've said still applies, the type of deltas I'm talking about can form in all three ways, so that's just yet another totally misleading statement and complete mischaracterization of what I'm saying.

Yes, that's typically also included as a criterion, i.e. a maximal degree of separation between the spots of 2 or 2.5 degrees. That's a perfectly fine and valid criterion, but not actually relevant to what's being talked about here at all, all the spots I've mentioned are well within that range. I even pointed to the very example used on this site itself on page 1, showing two different types of deltas, one where a large spot clearly retains a significant penumbra around it even if "surrounded" or "engulfed", and another where spots are much more "side-by-side".

I wonder if the differences are because it’s really more about the proximity of the umbrae (and thus the magnetic shear) than it is about the shapes and positions of the penumbral areas. That seems like it could be logical. Just brainstorming. 

[Philalethes]

Just now, WildWill said:

I must not have communicated my thoughts properly. Because it’s obvious that you didn’t understand my assertions. You did get one right - it’s not a delta unless they have merged to where a spot and it’s penumbra have enclosed, engulfed, surrounded, whatever synonym ya like here…, another spot of opposite polarity and the center of the spots must be within 2 degrees of each other.
 

Im gonna leave it there as we are not going to agree on this. That’s ok, if everyone agreed, it would be awfully boring around here. But, at some point ya gotta say - we ain’t gonna agree and that’s it! I don’t see much point in beating a dead horse - it ain’t gonna get the field plowed…

You're communicating your thoughts abundantly clear; it's just that some of those thoughts are clearly incorrect. For example, what you just repeated about how a spot has to be "enclosed"/"engulfed"/"surrounded"; this is at the core of your wrong claims. That's not necessary for an area to be classified as a delta at all.

That really has nothing to do with "agreeing" or "disagreeing", it's just a misconception on your part that you seem to can't let go of.

[Marcel de Bont]

I'm reopening this topic after deliberation with the mod team. This is a fun topic with a lot of potential for people to learn from. Delta sunspots are an important feature in complex sunspot region and it is valuable to be able to recognize them. However, debates can easily form on whether a sunspot region has a delta structure or not as it is not always very clear to see. Should such debates occur in the future in this topic please keep it civil and if you cant find a common ground, just agree to disagree and move on. Try to keep it friendly or actions will be taken by the mod team. Thanks for understanding and have fun posting!

[Philalethes]

On 2/11/2023 at 6:05 PM, Sam Warfel said:

degrees of separation

To expand a bit on this in addition to what I mentioned above, I've made a transparent grid that anyone who wants to can use as an overlay to more easily see roughly how many degrees of separation there are between spots:

On this grid each line is separated by exactly 1 degree, making it relatively easy to check if two spots are separated by 2 or 2.5 degrees depending on the definition used.

Here you can see what it looks like overlaid on the regular (not flattened) i-gram:

And here I've zoomed in on 3242, where a delta has formed for the time being:

As can readily be seen using the grid and looking inside the red rectangle I've marked, the separation between the bottom right negative spot and the top right positive spot is less than 1 degree, well within the bounds of what is defined as a delta.

Also noteworthy is the bottom left negative spot (also inside the red rectangle), as this was the first spot to form near the top positive one, but as you can see there's still quite a bit of visible separation between its surrounding penumbra and the shared penumbra of the two other spots. However, just to see how many degrees of separation there are between it and the positive spot in case the area strengthens or in similar cases, we see that the spots are roughly separated by the diagonal of a single square; as basic geometry tells us, this means a separation of roughly the square root of 2 degrees, which is ~1.414 degrees, and also well within the bounds of a delta.

Hope this is helpful for anyone who is looking for deltas, but are wondering if the two spots in question are too far apart to be counted as such. From virtually all the spots I've seen so far that part of the definition is rarely relevant, as spots of opposite polarity with shared penumbrae almost always are close enough, but I'm guessing it's more relevant for larger and highly active regions.

[Ester89]

The delta in this region seems quite obvious to me, but since I'm learning and I'm often wrong, I'm encouraged to ask... is this a delta?

[mozy]

2 hours ago, Ester89 said:

The delta in this region seems quite obvious to me, but since I'm learning and I'm often wrong, I'm encouraged to ask... is this a delta?

I want to say yes, but since they're still a bit separated from each other in the penumbral area I'd feel more safe to not say anything yet.

[Ester89]

38 minutes ago, mozy said:

Quiero decir que sí, pero dado que todavía están un poco separados entre sí en el área de penumbra, me sentiría más seguro si no dijera nada todavía.

Understand. Nothing about the sun is easy, not even what seems obvious. @mozy thanks for your patience and taking the time to reply.

[Sam Warfel]

Anyone want to have a go at circling all the deltas in this monster AR? I'm curious.
https://www.spaceweatherlive.com/en/solar-activity/sunspot-regions.html#3615

 

[mozy]

6 minutes ago, Sam Warfel said:

Anyone want to have a go at circling all the deltas in this monster AR? I'm curious.
https://www.spaceweatherlive.com/en/solar-activity/sunspot-regions.html#3615

 

But some are kinda vague to the displacement/separation of the penumbrae lately.

Edited March 24 by mozy

[hamateur 1953]

Just a public notice for those unaware.  Wild Will was definitely a personal friend and passed away last year after a protracted illness.  That’s about all I feel comfortable sayin here. Mike/ Hagrid. 

What I never noticed until just now is that @arjemma solved it to her credit.   I will never forget her finding that nanodelta in a mess of catbarf in a Northern Hemisphere region!!

[Sam Warfel]

26 minutes ago, hamateur 1953 said:

Just a public notice for those unaware.  Wild Will was definitely a personal friend and passed away last year after a protracted illness.  That’s about all I feel comfortable sayin here. Mike/ Hagrid. 

I think we had a public notice of such last year?  He is missed.

[hamateur 1953]

Yep. We did Sam. 

[Philalethes]

7 hours ago, Sam Warfel said:

Anyone want to have a go at circling all the deltas in this monster AR? I'm curious.

As of the latest imagery these are the clearest deltas I can see:

There are a couple more possible ones around the lower left part, but in those cases either of the umbrae are a bit too slight for them to really be called spots.