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What's chromospheric disk detail, and what are prominences?

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Well, there are several layers of the solar atmosphere. The lowest one is the Photosphere, which is the big bright disk we see when we look at the sun in the broad-band "white light" filters. The layer above this is a thin one called the "Chromosphere", due to its red color, and is normally only seen during a total solar eclipse when the moon completely blocks out the photosphere. At this time, the edge of the Chromosphere is visible as a red "fringe" around the edge of the sun. This fringe will have some details sticking up, such as spicules and Prominences. Prominences are emission features projecting beyond the limb of the sun,
consisting of complex clouds or streamers of gas above or in the chromosphere. They generally come in two broad classes: Active (limb flares, surges, sprays, loops), and Quiescent (Quiet Region Filaments, Active Region Filaments). This shape and forms vary, and they are quite fascinating to watch. However, with a very narrow band filter centered on the red emission line of H-alpha, the Chromosphere is visible and things like prominences can be viewed without having to have a solar eclipse. Spicules are part of the red "fringe" on the edge of the solar disk, and are very tiny jets of gas. Disk details are those details which are part of the Chromosphere and which are visible on the disk of the sun (filaments, plage, solar flares, ect.). To see prominences only on the limb requires a filter bandwidth of 1.5 Angstroms, while to clearly see the details on the disk requires something narrower (less than one Angstrom). Clear skies to you.

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David W. Knisely . . . . . . "If you aren't having fun in this hobby, you aren't doing it right."

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

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If the seeing is good enough, granulation can be seen visually in scopes larger than three inches, so it should be photographable as well. The granulation is the network of convection cells in the photosphere and is viewed in white light. In H-alpha (with a sub-angstrom filter), the granulation is generally not visible, being covered by the mass of spicules, fibrils, and other chromospheric detail known collectively as the "dark mottles". Clear skies to you.

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If the seeing is good enough, granulation can be seen visually in scopes larger than three inches, so it should be photographable as well. The granulation is the network of convection cells in the photosphere and is viewed in white light. In H-alpha (with a sub-angstrom filter), the granulation is generally not visible, being covered by the mass of spicules, fibrils, and other chromospheric detail known collectively as the "dark mottles". Clear skies to you.

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Interesting. Apart from those seen in Ha and white light, are there any particular features that can be seen by using good quality colour filters (e.g. Baader, see
www.baader-planetarium.de/download/color_Filter_e.pdf )?

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Well, some features in white light filters tend to be a bit more visible with some emphasis on one part of the spectrum. Granulation might be slightly more obvious in a green filter, and the brighter patches called "faculae" are sometimes a bit better in a filter which has a little more emphasis on the blue portion of the spectrum. Other than this slight enhancement, only narrow-band filters tend to add much detail, and this is mostly of the chromosphere. Clear skies to you.

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David W. Knisely . . . . . . "If you aren't having fun in this hobby, you aren't doing it right."

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

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