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difference between "active region" and sunspot?

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#1 gnowellsct

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Posted 17 July 2018 - 10:52 PM

I hate to sound like a total solar viewing noob but....since I only have one or two dozen hours experience, I think I am.

 

Last Thursday (12 July 2018) I had the Daystar quark + 102 mm refractor out and caught some nice prominence activity.  I am referring to visual observation, not photography.  Working with my variable polarizing filter, I was able to "tune the view" more for solar surface features and less for the prominences.  The prominences were distracting, to be sure, but I wanted to see what else was going on.  

 

I saw feathery thin gray lines curving (mostly in parallel) towards spot-like regions on the sun.  The spot like regions had no faculae or gray lines of their own.  (Which is not to say that such details might not emerge in imaging; I'm just saying what I saw)

 

Although I have seen sunspots in h-alpha I deceived myself into thinking that maybe they *were* sunspots--either sunspots that were emerging, or sunspots that were fading.  To double check I slapped on my Baader white light solar filter and saw....nothing.  Plain white disk.  I was half expecting to see real sunspots there.  

 

So, anyhow, reading the posts here, I'm assuming I saw two "active regions."  They were pretty close together. I'm inquiring whether that is true and what, if any, relation there is between a sunspot and an active region.  

 

Thanks for your help,

Greg N


Edited by gnowellsct, 17 July 2018 - 10:53 PM.

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#2 overnight

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Posted 17 July 2018 - 11:24 PM

Sunspots reside in active regions. They're places where the magnetic field lines inhibit convection and cool the area, causing the familiar dark spots.

 

Active regions are just regions characterized by high activity and stronger magnetic field lines, which can have a whole assortment of features like plages (bright patches), sunspots, and active region filaments.


Edited by overnight, 17 July 2018 - 11:24 PM.

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#3 MalVeauX

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Posted 18 July 2018 - 04:59 AM

As overnight pointed out, an active is just that, active. But it doesn't mean a spot (which will generally ultimately appear as a pair due to polarity) is present. But, it's more likely to have one, since it's more active. Activity being the magnetic field upwelling. In different wavelengths, you'll see different features. You can see the activity in hydrogen alpha fairly well, but it's a lot harder in white light (green light, 540nm, etc). In true Calcium light, you might see the faculae at least, if there's enough magnetic activity. Part of the fun is comparing views of the photosphere and chromosphere.

 

Very best,


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#4 gnowellsct

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Posted 18 July 2018 - 06:19 AM

Thank you both.

So active region filaments would be the gray lines I saw? I have seen similar lines around sunspots.

Edited by gnowellsct, 18 July 2018 - 06:19 AM.


#5 MalVeauX

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Posted 18 July 2018 - 11:08 AM

Thank you both.

So active region filaments would be the gray lines I saw? I have seen similar lines around sunspots.

Spicules and faculae lines. Filaments would appear darker as they're a prominence being seen from "above."

 

Very best,


Edited by MalVeauX, 18 July 2018 - 11:08 AM.

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#6 gnowellsct

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Posted 18 July 2018 - 02:20 PM

Well all right....what are the curved lines leading into the sunspots in this picture (on the left).  I don't think they're spicules, filaments, or faculae (which are like honeycombs).  

 

I think that's what I was seeing...curving lines in parallel, but no sunspot as terminus.  And I'm afraid not as dramatic.  But you could see they were there in polarized h-alpha.  They actually were visible without the polarizing filter, the polarizing filter just sharpened it up.

 

thanks for your help,

Greg N


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#7 MalVeauX

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Posted 18 July 2018 - 02:30 PM

Ahh ok, those are filaments in the penumbra. But, the word "filament" is being used to describe different things based on the wavelength of light we're studying. Filaments in hydrogen alpha for example are quite different than the filaments of a penumbra in photospheric wavelengths.

 

Very best,


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#8 gnowellsct

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Posted 18 July 2018 - 02:54 PM

Ahh ok, those are filaments in the penumbra. But, the word "filament" is being used to describe different things based on the wavelength of light we're studying. Filaments in hydrogen alpha for example are quite different than the filaments of a penumbra in photospheric wavelengths.

 

Very best,

Well h-alpha and white light are all I got so I guess I'm going to have to do a sketch or something if I see this again (and I didn't see these details in white light).  I haven't had much luck getting a surface view with a hand held smart phone so my options are limited.   Unless I can find something on the net.  I'll go rummage around.

 

Greg N



#9 gnowellsct

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Posted 18 July 2018 - 03:13 PM

Well this is a fundamentally similar picture with the same sunspot-related filaments and it says it's in h-alpha.  I actually don't know what filter is used for "photospheric wavelengths." 

 

I found this on S&T web site (h-alpha story):

 

"Much more obvious when looking at the H-alpha Sun for the first time are the bright, patchy plages (PLAH-jez) that mark the sites of active regions or sunspot groups. Don't be surprised if you see plage where no spot group is visible in white light. These are emerging flux regions (ERFs) where a magnetic flux tube is just breaching the surface on its way to producing a bipolar sunspot group.

 

"As for sunspots, their dark cores or umbrae look similar to what you see in white light, but the penumbrae branch out into impressive whirls of fibrils and spicules. When the seeing is excellent, you'll see an overwhelming amount of fibril/filament and plage detail in large sunspot groups. I used to attempt to draw them but with only one life to live, soon settled on sketching just the basic outlines."

 

I would have to say I was seeing "impressive whirls of fibrils" but there was no associated sunspot.  There was a kind depression or no-faculae zone (no fibrils either) where one might *think* a sunspot would be, but not there. 

 

I am not completely sure how a plage manifests in the combo quark.  Still this was a major feature.  I'm sure people here were imaging it.  The passage quoted above, "Don't be surprised if you see plage where no spot group is visible in white light," does get my attention since that's exactly the situation.  If I was observing a pair of plages then I suppose the "whirls of fibrils" can be part of the deal.  But these plages did not show as the kinds of bright bursts one sees in images.  They were, I suppose, brighter, in that you didn't see the lines of the faculae which tend to dim the solar surface a bit.  To me they just looked like clear zones of red.  I'm wondering if I fine-tuned the quark if I would get a different impression.

 

 

Greg N



#10 overnight

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Posted 18 July 2018 - 03:50 PM

They mislabeled it, the description clearly describes its white light and what was used. They used a 807nm IR pass.



#11 sushi1128

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Posted 18 July 2018 - 09:41 PM

Well all right....what are the curved lines leading into the sunspots in this picture (on the left).  I don't think they're spicules, filaments, or faculae (which are like honeycombs).  

 

I think that's what I was seeing...curving lines in parallel, but no sunspot as terminus.  And I'm afraid not as dramatic.  But you could see they were there in polarized h-alpha.  They actually were visible without the polarizing filter, the polarizing filter just sharpened it up.

 

thanks for your help,

Greg N

penumbral filaments



#12 gnowellsct

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Posted 19 July 2018 - 11:30 PM

so these pics look even more similar to what I saw...minus the sunspots.  The questions are in the pic.

 

sunspot questions.jpg



#13 ch-viladrich

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Posted 22 July 2018 - 01:57 PM

The "swichy lines" are called "fibrils". They are part of the chromosphere.

 

Spicules are also visible on this image.


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#14 gnowellsct

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Posted 22 July 2018 - 02:36 PM

The "swichy lines" are called "fibrils". They are part of the chromosphere.

Spicules are also visible on this image.


Thank you!
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#15 44ye

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Posted 23 July 2018 - 11:41 AM

gnowellsct

You might find this book a good reference 

Observing the Sun: A Pocket Field Guide
By Jamey L. Jenkins

 

Don


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#16 gnowellsct

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Posted 23 July 2018 - 05:02 PM

gnowellsct

You might find this book a good reference 

Observing the Sun: A Pocket Field Guide
By Jamey L. Jenkins

 

Don

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