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Luca, this is specatular!

Being a relative newbie to solar observing, especially H-alpha, I have a few questions regarding what I am looking at. To my untrained eye, I can see what I interpret as the leading sunspot in 11029, and its penumbra. If this is true, then I am seeing features on the photosphere, through the chromosphere....right?

The fine spicules (sp) at upper left appears to be directly over the smaller trailing spots. Can anyone explain them? Or, the bright filamentary structure between the lead spot and the smaller trailing spots?

Thanks!

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What is being shown in H-alpha is primarily in the chromosphere. The Umbra of the sunspot is clearly visible, but it is surrounded by a network of fine radial filaments which is in the same general area as the white-light penumbra but often exists somewhat higher above the surface than the white light penumbra (a sort of "H-alpha penumbra"). These fibrils often connect to more distant elements of the chromosphere's "magnetic network" somewhat beyond the normal bounds of the photospheric penumbra, so while the two features are related, they are not necessarily identical. With broader bandwidth filters, the penumbra can sometimes be seen, but here in the above image, we are mainly looking at overlying structures which can be somewhat above the penumbra. If you directly compare a white-light and H-alpha image, you will see similarities, but there are some differences.

The bright patches over the trailing areas with the smaller sunspots are the bright elements of plage. Plage represents areas where the local magnetic field is realigning rapidly due to flux emergence (a new magnetic dipole emerging under existing fields). Plage and white-light faculae are related, but are not exactly the same thing, as their locations are often not precisely the same. You can see arch-like short filaments known as the "arch filament system" (AFS) which run between the opposite magnetic polarity regions in the plage. The AFS is an indicator of the emergence of more flux, possibly producing new sunspots. The fine fibrils and short filaments usually connect areas of opposite polarity, so you can think of them the same way you can think of the structure you might see when putting a bar magnet under a piece of paper with iron filings on the top. The fibrils and shorter filaments trace out some of the magnetic field structure found in the chromosphere. For more general information about H-alpha features, check out the following article:

OBSERVING THE SUN IN H-ALPHA

Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org

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