How often do C-Class or higher flares originate from plage-only areas on the visible solar disk with no AR (no sunspots)?

Qualitatively, the answer is not often, but what is the quantitative answer, historically speaking?  For all C-class or higher flares, what percent occurred in plage-only areas on the solar disk (i.e. not including flares along the limb or slightly behind the limb where existence or nonexistence of sunspots cannot be determined)?

Who says it was spotless when the C-flare occurred? It was still behind the limb and could still have spots on the moment of the flare before vanishing and turning into view as a spotless plage.

1 hour ago, Vancanneyt Sander said:

Who says it was spotless when the C-flare occurred? It was still behind the limb and could still have spots on the moment of the flare before vanishing and turning into view as a spotless plage.

Exactly, we don't know.  That's why I was excluding limb flares from consideration (though I may not have worded it clearly).  But now that those areas are visible on the solar disk, it will be an interesting test case to see if any C-flares occur from those plages (though sunspot formation could be imminent).

Speaking from 2 solar cycles of hobbyist observation, I can't remember seeing a flare on the visible hemisphere without associated sunspot.
But as solar activity increases, small flares become less interesting and attention is drawn to the bigger spots. So my experience is certainly not a quantitative measure  

In the end, the question whether there is or was a spot associated to a flare, is also limited to the spatial and temporal resolution of the available imagery.

tldr; I'm not aware of a source which keeps track of that.

 

4 uren geleden, Drax Spacex zei:

But now that those areas are visible on the solar disk, it will be an interesting test case to see if any C-flares occur from those plages

Normally they don’t flare, unless there’s a filament attached to it 🤷‍♂️ Plages are also called a graveyard of a sunspot region so there isn’t any “life” in terms of solar flares (but who knows that a plage can cause a zombie flare 😝). Something to keep an eye on but normally it’s pretty dead ☺️

Thanks for your replies - they are appreciated.  I read a few articles which indicate the same - that a "bright spotless faculae field" may look impressive in some wavelengths in brightness and area, and may contain a few pores, but without sunspots, it's unlikely to produce significant (C or higher) flares.

Edited July 2, 20214 yr by Drax Spacex
significant (C or higher)

For this test case, the strongest flare from this large spotless plage area during its traversal from east to west across the solar disk was B7.1 on 2021-06-29 05:39 UTC.

AR2849, recently downgraded to a spotless plage area, produced a B9.8 flare on 2021-Jul-27 22:26 UT.  Round it to the nearest whole number and call it a C1.  Nothing impressive, but worth noting in the scope of this topic.

3 hours ago, Drax Spacex said:

AR2849, recently downgraded to a spotless plage area, produced a B9.8 flare on 2021-Jul-27 22:26 UT.  Round it to the nearest whole number and call it a C1.  Nothing impressive, but worth noting in the scope of this topic.

I wondered where this flare originated too! I also saw it was 2849. The solar disc is more or less spotless now. There were a lot of sigmoids detected around the Active Region so obviously there's a lot going on under the surface magnetically, it's just not producing spots. The two B5 flares were from AR2846, but something is flaring again just now!

Edited July 28, 20214 yr by Newbie

Groan!!

No sunspots, no flares, nothing around the corner, the Sun looks like a yellow pool ball or this smiley face .

On 7/30/2021 at 6:52 AM, Newbie said:

Groan!!

No sunspots, no flares, nothing around the corner, the Sun looks like a yellow pool ball or this smiley face .

Beneath the calm surface,

Explosions blossom with fire,

Tied in electron knots, 

And flung into the terrible night,

To decorate the sky. 

Edited July 31, 20214 yr by Archmonoth

On 7/28/2021 at 2:12 AM, Newbie said:

There were a lot of sigmoids detected around the Active Region

Ah, now I know the official name for those - sigmoid (not the anatomical kind).

I might have previously called them a squiggle, a snake, a serpent, a dragon, or like Malcolm McDowell, "the nexus."

Perhaps that's a reason why so many are excited about an increasingly active Sun - the nexus is almost in reach.  (Just remember it isn't real.)

I think i remember a B-Class enhancement from an area of Plage. I'm not sure tho, I think it makes more sense that it briefly reemerged, flared and died down again.

1 hour ago, Drax Spacex said:

 sigmoid (not the anatomical kind).

It conjures up pictures of an 'S' bend in my mind! The plumbing kind!

It's funny because the name given to the means of detection is 'Sigmoid Sniffer' and every time I read it, I smile!  😜

Oh I appreciate a good haiku! 😃

7 hours ago, Archmonoth said:

Beneath of the calm surface,

Explosions blossom with fire,

Tied in electron knots, 

And flung into the terrible night,

To decorate the sky. 

Archmonoth you have thrown down the challenge! 

Image courtesy of SDO/AIA! It is called the Sigmoid Sniffer module - I kid you not!

On 7/31/2021 at 3:11 AM, Archmonoth said:

Beneath the calm surface,

Explosions blossom with fire,

Tied in electron knots, 

And flung into the terrible night,

To decorate the sky. 

Writhe! wrestling serpents,

Twisted tangled coils,

Seething furnace: Sun. 

Tempered for a season,

List' the cry! "how long"?

 

Edited August 1, 20214 yr by Newbie
Really bad punctuation!

21 hours ago, Newbie said:

Writhe! wrestling serpents,

Twisted tangled coils,

Seething furnace: Sun. 

Tempered for a season,

List' the cry! "how long"?

 

 

Night and day are spotless,

When waiting for the blaze,

Forged by rotten hands,

Dawn can not erase. 

Edited August 1, 20214 yr by Archmonoth

Sleeping sun sans spots
Failing faculae field flares
Henceforth hath haiku

Edited August 2, 20214 yr by Drax Spacex
5/7/5 haiku + tongue twister

What is this arisen?

What has our Sun brought forth?

Deep in the Southern regions,

A long dead plage gives birth!

Hail! Phoenix, zombie sunspots,

Rise up to greet your day,

May you grow and prosper.

You better not decay! 

 

Courtesy SDO/HMI latest!

Edited August 1, 20214 yr by Newbie
Can't spell!

Haha - Yeah that's right on the cusp of becoming an AR - not quite as far south as AR2844 from a few weeks ago - but pretty far down there.  It's got some sizzle, let's see if it has any pop!

Why do organizations such as SILSO continue to use a network of contributing stations when SOHO exists?

Surely one perfect image unaffected by weather is all that is needed?

We use STEREO-A to see what is coming. That is only one image.

@dave
Spacecrafts can and will be unavailable at times, or they may fail entirely. For example during radiation storms, technical issues or old age. 
Furthermore, ground based observatories may be easily modified for example to host new instruments, which can't be done easily on spacecraft.
That's why it is important to maintain independent observatories.

Last week EPAM from SWPC ACE was offline for around 48 hours, there were a few posts about it.  

Good to have more than one source of data.  😃

 

Edited August 2, 20214 yr by Newbie

There seems to be sufficient redundancy (i.e. alternative, active, instrument feeds) and sufficient upgrading (new launches) in the system of space-based instrumentation that one can rely on there (almost always) being an acceptable image of the sun's disc. I really cannot remember a single occasion in the last ten years when one could not obtain detailed information (magnetograms, UV etc.) from some live feed or other (SDO, SOHO, STEREO-A...).

Almost all of the instruments for monitoring the Earth and the Sun have exceeded expectation. 

If the gentlemen of SILSO want to do things the old way, well, in a sense that is their mission, accepted by them in 1981 - to perpetuate a particular, long-lived, project of astronomers, and extend the resulting historic series into the present.