Also seen in hydrogen-alpha light, this tail is appears shorter and was found not to contain any intracluster HII regions like those seen 'downstream' from ESO 137-001.    From Wordnik.com.  [How Galaxies Lose Their Gas | Universe Today] Reference

When looking at it through a hydrogen-alpha filter, the sun glowed a deep, blood red, surrounded by a black background.    From Wordnik.com. Reference

Understanding the best way to view the sun is by segregating the hydrogen-alpha wave length at 656. 3nm and removing all types of light emitted by the sun.    From Wordnik.com.  [MyLinkVault Newest Links] Reference

(a) Image of the disc of the Sun in the light of the hydrogen-alpha spectral line a couple of minutes after the onset of the event with model magnetic field lines superimposed. (b) A zoomed-in image of the active region concerned, again with a set of model magnetic field lines superimposed. (c) As in (b), but without the model superimposed showing the detail of the event in the image.    From Wordnik.com.  [PhysOrg.com - latest science and technology news stories] Reference

At the Sun Study Center in Boulder, Sam Cottage turned the cranks which moved his solarscope into position, brought the hydrogen-alpha filter into the optics in order to obtain the most sensitive view of activity on the Sun, and waited for the great star to lose its redness so he could get a clear look at its face, and when he did so he saw that Region 419 had reached the precise spot from which it could create the maximum danger.    From Wordnik.com.  [Space]