Tuesday, 20 August 2019

Polar Faculae & Cycle 25 Jet Streams - 17th August

The sun may on the face of it be blank at the moment, but there are plenty of subtle signs visible of where we are in relation to solar cycles.  The image above in the top half of the image shows bright polar faculae,  these are magnetic areas on the sun, not strong enough to form sunspots or pores, but strong enough to be visible in a variety of wavelengths; in white light they are visible as white spots on the photosphere, but, higher up in the chromosphere in Ha wavelengths they appear as small bright jet like features shooting upwards.  They only form in the polar regions at solar minimum as the magnetic fields are stable at this time, during solar maximum the poles are under going a magnetic field reversal and so polar faculae are unable to form.

In the bottom half of the image we can see small, dark filaments; regions of plasma held aloft by magnetic fields, however these magnetic fields are in the jet stream regions where we expect to see the tell tale signs of cycle 25.  While these magnetic fields are still quite weak, only able to support filaments, over time their field strength in gauss will increase enough for them to start developing first of all pores and then sunspots, with developed umbra and penumbra.

Taken with the 90mm Coronado SolarmaxII telescope double stacked with a Daystar Quark to increase image contrast by reducing continuum leakage into the image.