What Causes certain sunspots to rapidly evolve?

[Reesepuff]

After watching sunspots for the last year or so and digging into a whole bunch of archives I've noticed something. What I noticed is any sunspot that has given off an X-flare has been a rapidly evolving sunspot. Basically more than doubling in size in 24 hrs. A perfect example of this is AR13354

https://www.spaceweatherlive.com/en/solar-activity/region/13354.html
 

this sunspot may not have given off an X-flare but it rapidly evolved.

 

another better example is in 2017 AR12673 rapidly evolved into a Beta-Delta-Gamma sun spot giving off quite a few X-flares in the 8.0 area.

https://www.spaceweatherlive.com/en/solar-activity/region/12673.html

 

 

what causes these sunspots to develop so fast and what makes them correlate to strong solar flares?

Edited July 4, 2023 by Reesepuff
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[Newbie]

@Reesepuff
Sunspots are dark, cooler areas on the surface of the Sun that are associated with intense magnetic activity. While sunspots can vary in size and growth rate, their rapid growth is primarily influenced by two main factors: magnetic field strength and convective processes.

Magnetic Field Strength: Sunspots are formed when intense magnetic fields emerge from the Sun's interior and break through the surface. The growth of sunspots is closely related to the strength and complexity of these magnetic fields. When the emerging magnetic fields are strong and concentrated, they can inhibit the convective motions of the surrounding plasma, leading to a localized cooling effect and the formation of a sunspot. If the magnetic field strength increases rapidly, the sunspot can grow quickly as more magnetic flux is added to the region.

Convective Processes: The convective motions within the Sun play a role in the growth of sunspots. Convective cells transport heat from the solar interior to the surface, and they can interact with the emerging magnetic fields. When the convective motions encounter strong magnetic fields, they can be suppressed, reducing the heat transport in that region. This suppression leads to a cooler area, which appears as a sunspot. If the convective processes are hampered or disrupted by the magnetic fields, the sunspot can expand rapidly.

The exact mechanisms behind sunspot growth are still not fully understood. Scientists continue to study sunspots to improve understanding of the Sun's magnetic activity and its impact on space weather.

N.

Delta spots are specific types of sunspots characterized by a distinct penumbra structure and a complex magnetic field configuration. They are known to exhibit rapid growth and are often associated with intense solar activity, including solar flares and coronal mass ejections (CMEs). Several factors contribute to the rapid growth of delta spots in sunspots:

Magnetic Flux Emergence: Delta spots form when new magnetic flux emerges from the solar interior and interacts with the existing magnetic field on the surface. This emergence of magnetic flux can occur through various processes, such as the buoyant rise of twisted magnetic structures known as flux ropes.

Magnetic Shear and Reconnection: The emergence of new magnetic flux can lead to the formation of magnetic shear, which refers to a significant change in the direction or strength of the magnetic field. Shear can induce magnetic reconnection, a process where the magnetic field lines rearrange and release a tremendous amount of energy. The reconnection process fuels the rapid growth of the delta spot by allowing the magnetic field to expand and intensify.

Sunspot Umbra-Penumbra Formation: Delta spots have a characteristic penumbra structure surrounding their central umbra. The penumbra is an area of the sunspot where the magnetic field is more inclined, and it is associated with strong convective flows. These convective motions help transport heat and energy from the solar interior to the sunspot, further fueling its growth.

Sunspot Interactions: Delta spots often form in regions where multiple sunspots or active regions converge. The interaction between different sunspots can trigger an amplification of magnetic fields and lead to the rapid growth of the delta spot.

Energy Release and Flares: Delta spots are frequently associated with solar flares, which are sudden and violent releases of energy in the form of electromagnetic radiation, particles, and plasma. The intense magnetic field configuration and rapid growth of delta spots make them prone to such explosive events. Solar flares can further enhance the growth and complexity of the delta spot by releasing additional energy and disrupting the surrounding magnetic field.

N.

Edited July 6, 2023 by Newbie
Delta formation

[Philalethes]

On 7/5/2023 at 1:16 AM, Reesepuff said:

After watching sunspots for the last year or so and digging into a whole bunch of archives I've noticed something. What I noticed is any sunspot that has given off an X-flare has been a rapidly evolving sunspot. Basically more than doubling in size in 24 hrs. A perfect example of this is AR13354

https://www.spaceweatherlive.com/en/solar-activity/region/13354.html
 

this sunspot may not have given off an X-flare but it rapidly evolved.

 

another better example is in 2017 AR12673 rapidly evolved into a Beta-Delta-Gamma sun spot giving off quite a few X-flares in the 8.0 area.

https://www.spaceweatherlive.com/en/solar-activity/region/12673.html

 

what causes these sunspots to develop so fast and what makes them correlate to strong solar flares?

If you check out the first part of this post, I provided the most commonly accepted hypothesis of the underlying reason for why sunspots form in the first place; in short it has to do with the fact that highly conductive fluids and the magnetic fields embedded in them will tend to move together within certain constraints (Alfvén's theorem). Thus due to the differential motion of the Solar surface (rotating faster near the equator, and differently at various depths too) the magnetic fields get stretched out and twisted as illustrated in the diagram there.

So put in as simple terms as I'm able to, based on my understanding of it, this in turn causes irregularities in the structure of the magnetic field, and given that the plasma and the magnetic field wants to move together, this can essentially lead to situations where the plasma wants to move but the magnetic field is unable to stretch or twist further to accommodate the movement; essentially you get a "traffic jam" to use a simple analogy, and if the magnetic tension is strong enough you get a full-on "collision" where the stretched and twisted irregularities of the magnetic field are pushed up above the Solar surface. As Newbie mentions above, this part of the field emerging from the surface is hypothesized to further prevent convection and thus leading to the cooler area we recognize as sunspots.

Given this analogy, the reason for the spots growing so rapidly in some cases would be that there must already be a lot of magnetic field tension that has built up over time due to the stretching and twisting of the field, and thus that when the "collision" happens more magnetic flux will get pushed up above the surface, and typically in more complex configurations too.

The reason for why this in turn would be associated with more and stronger flares and eruptions is that those events are hypothesized to occur due to magnetic reconnection (as also mentioned briefly in the post referenced above), which are relatively discontinuous events where magnetic fields under high tension rapidly reorganize themselves to more stable configurations, converting a lot of that built-up magnetic energy into kinetic energy in a very short period of time, identifiable to us as flares due to how this kinetic energy excites particles in the corona to highly energetic states from which they drop down and emit correspondingly highly energetic photons, and as coronal mass ejections if the magnetic field configuration is conducive to enough magnetic reconnection for some of the corona to be ejected out into interplanetary space.

There are probably a lot of inaccuracies in that picture, and many of these processes are definitely not well understood yet at all, but it's the best I can do based on a combination of what I know to be the leading hypotheses about the origins of Solar activity and my own understanding of the subject. Hopefully it's of some help, if only to point in the direction of what to investigate on your own.

Edited July 6, 2023 by Philalethes
typo & grammar