English: It's been too long since I've done an old WFPC2 image. A recent discussion led me to look up pictures of the Bubble Nebula and when I saw the version available at HubbleSite, I figured I should try it. If anything, at least get rid of that big charge bleed around the bright star at the bottom.

If you're familiar with the Bubble Nebula, you know it's actually one of those red, glowing areas of H-alpha. This image is composed of three narrowband red filters. The blue colors here are actually H-alpha (f656n) which I have blended together with the green channel so that it is a bit brighter and easier to see. The green channel is also representing [N II] (f658n). H-alpha and [N II] emission lines are only separated by 2 nanometers. They are awkwardly close. A little more separated is the [S II] filter (f673n) represented by red. The colors are not very pure but it's enough you can see for sure that those bright, clumpy pillars are a little more strongly represented by [S II]. They do glow brightly in each all three channels on their star-facing sides so they appear white on one side and pink on the other.

If that confused you then I would recommend reading the article I linked to earlier. There's wind, and gas, and atoms of various types are glowing.

Red: hst_07515_01_wfpc2_f673n_wf_sci Green: hst_07515_01_wfpc2_f658n_wf_sci + hst_07515_01_wfpc2_f656n_wf_sci Blue: hst_07515_01_wfpc2_f656n_wf_sci

North is almost up. It's 4° counter-clockwise from up.