22nd March 2020 Polar faculae

[Montana]

Finally some progress today. Here is my data for 22nd March, I have only concentrated on the South pole although I do have data for the North pole but as it has taken me 2 days to do the south I am a restless and want to get out in the garden.

Seeing was terrible so images are not great quality, orientation was a nightmare still for Hydrogen alpha even with great care setting up the camera.

Equipment: All set to 100mm aperture + 2x Barlow - TEC140, Baader Herschel Wedge + Continuum filter, Lunt CaK wedge, Solarscope DSF100. Camera ASI174 throughout.

South Polar faculae 2020-03-22 quadrants by Alexandra Hart, on Flickr

South Polar faculae 2020-03-22 cropped figure by Alexandra Hart, on Flickr

Hydrogen alpha full disc 2020-03-22 f colour by Alexandra Hart, on Flickr

Hydrogen alpha full disc 2020-03-22 tilting Sun a by Alexandra Hart, on Flickr

Calcium K full disc 2020-03-22 f colour by Alexandra Hart, on Flickr

Calcium K full disc 2020-03-22 tilting Sun by Alexandra Hart, on Flickr

White Light full disc 2020-03-22 a by Alexandra Hart, on Flickr

White Light full disc 2020-03-22 tilting Sun by Alexandra Hart, on Flickr

Alexandra

[pedro]

Very interesting stuff Alexandra

The images are great in spite of the faie seeing

Be healthy, be safe, be well

[marktownley]

Looks like you had a productive run there with some excellent images. It's nice we have the sun shining for a change.

[JochenM]

Looks like you had a really fun and productive session there.

Nice results.

[DeepSolar64]

Excellent results Alexandra. Concentrating on the polar faculae is an interesting study. Your Tilting Sun overlays look good too and take out any question of the sun's orientation.

In Ha wouldn't they be known as " polar plages "? I know plages in the chromosphere usually overlay the faculae seen on the photosphere. It's probably easier to label them all as the same feature in this case because they are all connected. What causes them? I know they are a feature of solar minimum.

James

[Montana]

You are absolutely correct James, I am studying the polar faculae (white light) and seeing if any features are visible in the chromosphere. In the chromosphere (both CaK and Halpha) they are called plage.

Faculae are magnetically weak regions whereas sunspots are magnetically intense. They are about 100K hotter than the surrounding photosphere). There is much argument as to why we see a bright area but the old fashioned theory is that the weaker magnetic field produces a weak Wilson effect (think of a strong magnetic field which results in a sun spot). This small depression means that at the poles (the edge of the disc) we are looking more horizontally across and seeing light emerging through the side walls of the depression (100K hotter) and so we see veins of light. Plage on the other hand is a result of underlying flux tubes emerging and reconnection, but this is all part of the field line structure. Some of the faculae correspond with bright plage in the Halpha but some correspond with dark spicule bushes, so obviously there seems to be two events going on in the chromosphere where we see only one feature in the photosphere.

Polar faculae are most numerous on the rising phase of the new cycle, then vanish altogether during maximum, then they suddenly reappear again at the top. A bit like the sunspots start at 50 degrees and migrate south to the equator during maximum, I expect the polar faculae start at the pole and migrate south and because you can't see faculae apart from at the limb this is why they gradually disappear while the field lines migrate south during the maximum.

Hope this helps a bit.
Alexandra

[DeepSolar64]

Thank you Alexandra. I have read some on this but your explanations clarify it a bit.

Do you think I could pick them up in a DSLR image? If I could get a sharp enough image that is exposed correctly and edit it in GIMP to reveal them? White light of course.

James

[ffellah]

What an incredible amount of diligent work you did, Alexandra. Well done !

Franco