Evidence of the Solar Dynamo?

[3gMike]

I could not help noticing the configuration of magnetic fields in the northern hemisphere over the last few days. Are these tilted lines of alternating polarity evidence of the solar dynamo at work?

 

[Sam Warfel]

I noticed that too, it’s really interesting looking 

[Drax Spacex]

Or the wake of a speedboat racing across (or beneath) the solar equator from east to west ... again, me and my analogies!  

Carrington Rotation Magnetogram Synoptic Map Movie:

https://gong.nso.edu/data/magmap/cr_movie.html

Edited May 5, 2022 by Drax Spacex
added cr movie link

[3gMike]

6 hours ago, Drax Spacex said:

Or the wake of a speedboat racing across (or beneath) the solar equator from east to west ... again, me and my analogies!  

Carrington Rotation Magnetogram Synoptic Map Movie:

https://gong.nso.edu/data/magmap/cr_movie.html

Nice movie!

It is quite tricky attempting to represent rotation on a 2D image. I was initially confused by the earlier time being on the right of the image, but it makes sense when you think about it.

Edited May 5, 2022 by 3gMike
Further observation

[Drax Spacex]

These tilted lines of opposite polarity could be the disintegration and dispersion of large ARs from previous rotations.

[farm24]

could also be a sensor artifact too

[WildWill]

Hi 3,

I just saw this for the first time. Interestingly enough we have those large regions, all parallel, at the same angle to the vertical. The other thing that struck me was there was heavier action down on the south - mid latitudes. That’s kinda what we had the last few days except, from the southern tropical region all the way up to the poles, it has been very quiet - on all the wavelengths they are capturing here, along with the magnetometer. If you turned the contrast down on this so that you couldn’t see the green and yellow stripes at the top, then the bottom would be a good deal dimmer, and much like it has been the last few days!  

Just an observation. I have a couple more to put down on paper after while. 

Or am I imagining things?

Cheers!

W

[David Silver]

The angles of these magnetic field reminded me of Scott McIntosh’s work:

Solar cycle overlap

[3gMike]

16 hours ago, WildWill said:

Hi 3,

I just saw this for the first time. Interestingly enough we have those large regions, all parallel, at the same angle to the vertical. The other thing that struck me was there was heavier action down on the south - mid latitudes. That’s kinda what we had the last few days except, from the southern tropical region all the way up to the poles, it has been very quiet - on all the wavelengths they are capturing here, along with the magnetometer. If you turned the contrast down on this so that you couldn’t see the green and yellow stripes at the top, then the bottom would be a good deal dimmer, and much like it has been the last few days!  

Just an observation. I have a couple more to put down on paper after while. 

Or am I imagining things?

Cheers!

W

I agree that we have seen a period where the southern hemisphere has been more active. That is likely to change in the next few days when the large active zone currently on the farside shows up.

Another way of looking at the diagonal stripes showed up particularly well on the synoptic map from 30th June

16 hours ago, David Silver said:

The angles of these magnetic field reminded me of Scott McIntosh’s work:

Solar cycle overlap

I understand why you made that connection, but the timescales are very different. Scott is referring to the shift in latitude of sunspot activity over the solar cycle, which is also demonstrated by the butterfly diagram.

I think that the diagonal stripes we are looking at are possibly related to the differential rotation rate at different latitudes.

[WildWill]

Hi 3g,

As I understand it, the sun axis of rotation is tilted about 5* from the elliptic.  The earth’s axis is tilted 26* from the elliptic. Elliptic being the plane of the solar system. While the earth’s orbit is not exactly aligned, close enough for this purpose…

When we look at the drawing above,  what does N mean “aside from the general description of North). More specifically, how would one dra the sun’s axis of rotation on this diagram, do you know?

thanks.

W

[Archmonoth]

On 5/4/2022 at 12:11 PM, 3gMike said:

I could not help noticing the configuration of magnetic fields in the northern hemisphere over the last few days. Are these tilted lines of alternating polarity evidence of the solar dynamo at work?

 

Cool picture! Yeah, looks like there is some shearing action going on. 

 

I was able to find something close to modeling the idea of a gyroscopic dynamo with a liquid medium: 

 

 

This is of course an imperfect model. 

 

Here is another video of a gyroscope being carried around, you might notice the flipping of the exterior ring, this would be perhaps akin to the magnetic polarity flipping from each solar cycle. (Starting at 40 seconds)

 

 

Edited July 3, 2022 by Archmonoth

[3gMike]

Yes, the sun's axis is tilted 7.25* from the ecliptic in a direction from Earth that means we see more of the South pole in March and more of the North Pole in September. The Earth's axis is tilted by 23.5* in a direction that means our North pole faces toward the Sun in June and away from the Sun in December.

That, and the fact that sunspots track the lines of latitude, suggests that the plot is Sun-centric and therefore rotation is the same as the E-W axis.

[Archmonoth]

1 hour ago, 3gMike said:

Yes, the sun's axis is tilted 7.25* from the ecliptic in a direction from Earth that means we see more of the South pole in March and more of the North Pole in September. The Earth's axis is tilted by 23.5* in a direction that means our North pole faces toward the Sun in June and away from the Sun in December.

That, and the fact that sunspots track the lines of latitude, suggests that the plot is Sun-centric and therefore rotation is the same as the E-W axis.

To me this suggest that the E-W rotation is like gimbal lock in the gyroscope analogy above. (i.e., part of the dynamo is locked to the rotation of the other bodies in the system). 

Edited July 3, 2022 by Archmonoth

[3gMike]

7 minutes ago, Archmonoth said:

To me this suggest that the E-W rotation is like gimbal lock in the gyroscope analogy above. (i.e., part of the dynamo is locked to the rotation of the other bodes in the system). 

I will need some time to get my head around that. 

I've been reading an interesting article in an attempt to understand better what is happening at different levels in the sun. https://nap.nationalacademies.org/download/10993

(You may have to sign up to gain access - no cost involved)

[Drax Spacex]

On 5/4/2022 at 3:11 PM, 3gMike said:

I could not help noticing the configuration of magnetic fields in the northern hemisphere over the last few days. Are these tilted lines of alternating polarity evidence of the solar dynamo at work?

 

The tilt of these polarity lines of magnetic field have a negative slope in the northern hemisphere; positive slope in the southern hemisphere.  For the whole disk, it often looks like a larger greater-than symbol ">" .

I would hazard a guess that the slope is due to the differential rotation speed of the Sun as a function of latitude.  Features at higher latitudes lag behind those closer to the equator.

[Sam Warfel]

4 hours ago, Drax Spacex said:

I would hazard a guess that the slope is due to the differential rotation speed of the Sun as a function of latitude.  Features at higher latitudes lag behind those closer to the equator.

If the lower latitudes rotate faster, than the discrepancy between the lower and high must therefore be increasing, which means the sun is (slowly or not-so-slowly, I don't know the speed proportions) twisting itself up, so to speak.  Does the sun ever "snap" when the twisting gets to a certain point and low latitudes jump ahead, or is the sun fluid enough that the twisting is continually released by "slipping"? Another way to put my question is whether the sun twists like a twisted dishcloth (eventually, something must snap) or a whirlpool, where material is always swirling along at different speeds than its neighbors, creating turbulence?

[Dr. I]

Wow, I think the radial distance is more important here than the latitude. But very cool questions.

 

[Archmonoth]

3 hours ago, Orneno said:

If the lower latitudes rotate faster, than the discrepancy between the lower and high must therefore be increasing, which means the sun is (slowly or not-so-slowly, I don't know the speed proportions) twisting itself up, so to speak.  Does the sun ever "snap" when the twisting gets to a certain point and low latitudes jump ahead, or is the sun fluid enough that the twisting is continually released by "slipping"? Another way to put my question is whether the sun twists like a twisted dishcloth (eventually, something must snap) or a whirlpool, where material is always swirling along at different speeds than its neighbors, creating turbulence?

My guess is that since it is magnetized plasma, the flows might be pinching. Pinch (plasma physics) - Wikipedia 

[3gMike]

9 hours ago, Drax Spacex said:

I would hazard a guess that the slope is due to the differential rotation speed of the Sun as a function of latitude.  Features at higher latitudes lag behind those closer to the equator.

Yes, that is my feeling too, but it does require the original Active region to span quite a large range of latitudes. There is a hint of something like that in the original image posted May 4th. Looking at the Sothern Hemisphere, close to the West limb you see some almost vertical bands. It will be interesting to see if they have spread in subsequent rotations.

Given that there are a couple of days difference in rotational rate between 30 (26 days) and 60 (28 days) degrees latitude, means it would take something in excess of 6  rotations to produce the effect seen in the image.

[Drax Spacex]

Yes, that long-term view would be telling, if the magnetic field lines persist and do not dissipate completely across rotations.

For clarity, the usage of the term "high latitude" in Sun-speak means high numbers for either North latitude or South latitude (e.g. N80° and S80° are both "high latitude").

I like the gyroscope videos.  The analogy does seem to apply that there is a driving rotational force (a ring?) somewhere below the Sun's surface near the equator.  That is the apparent resultant force at least.  Who knows what really lies beneath.