Part of the planetary nebula NGC 2899 has the rough shape of a butterfly. The oxygen ion emission line in UV enables its presentation with the false color of blue.
When protons capture electrons the result is either Lyman or Ballmer series emission lines, depending on the orbital the electron takes.
The red fringe can come from the hydrogen Ballmer-alpha emission line which is truly in red.
Lyman-alpha emission line is in ultraviolet.
Ballmer-beta line is aqua while Ballmer-gamma is blue.
story with false colored image
Caption for the image:
This highly detailed image of the fantastic NGC 2899 planetary nebula was captured using the FORS instrument on ESO’s Very Large Telescope in northern Chile. This object has never before been imaged in such striking detail, with even the faint outer edges of the planetary nebula glowing over the background stars.
Excerpt from the story:
This particular nebula is at a very high temperature, with the hot gas glowing to create the visual effect.
“NGC 2899’s vast swathes of gas extend up to a maximum of two light-years from its center, glowing brightly in front of the stars of the Milky Way as the gas reaches temperatures upwards of 10,000 degrees [Celsius],” ESO scientists explained in a statement. “The high temperatures are due to the large amount of radiation from the nebula’s parent star, which causes the hydrogen gas in the nebula to glow in a reddish halo around the oxygen gas, in blue.”
Astronomers believe that the nebula developed its unusual shape because it has two central stars, which push out and illuminate gas in a symmetrical way. This type of nebula is called bipolar, and only around 10% to 20% of nebulae are of this type.
The image was captured using the FORS instrument on the VLT, standing for FOcal Reducer and low dispersion Spectrograph, which images in the visual and near-ultraviolet light wavelengths.
There is no glowing at ridiculous temperatures from distant stars.
The red on the fringes comes from protons capturing electrons. The UV from the oxygen is from their capture of electrons. Just because the atoms are ions does NOT mean these ions are at the ridiculous temperature.
There are no stars "which [can] push out and illuminate gas in a symmetrical way."
There is no wind in space.
The sharp edge on the nebula cannot be just gas and dust. Any edge cannot be anything other than a liquid or solid. Loose particles cannot form and maintain an edge until bonded.
A likely possibility is the internal edges of the nebular are condensed matter, or metallic hydrogen (just protons and electrons) which can be liquid when not compressed to a solid.
The diffused glow near the edge suggests electrical acivity like in the solar corona.
This image from APOD reveals this entire nebula consists of plasma filaments.
Here tthe "buttrerfly" is slightly below and right of center and is without the false blue color.
Unlike the other image, APOD shows red and other colors everywhere else but in the butterfly.
Artists make these celestial objects more interesting.
Its caption mentions the ridiculous temperature:
Can stars, like caterpillars, transform themselves into butterflies? No, but in the case of the Butterfly Nebula -- it sure looks like it. Though its wingspan covers over 3 light-years and its estimated surface temperature exceeds 200,000 degrees, C, the dying central star of NGC 6302, the featured planetary nebula, has become exceptionally hot, shining brightly in visible and ultraviolet light but hidden from direct view by a dense torus of dust. This sharp close-up was recorded by the Hubble Space Telescope and is reprocessed here to show off the remarkable details of the complex planetary nebula, highlighting in particular light emitted by iron, shown in red. NGC 6302 lies about 4,000 light-years away in the constellation of the Scorpion. Planetary nebulas evolve from outer atmospheres of stars like our Sun, but usually fade in about 20,000 years.
The iIron emission line is not red so this is a false color from what an eye will see.
" Planetary nebulas [do not] evolve from outer atmospheres of stars like our Sun."
The complex filamentary structure in the nebula was definitely not a slow evolution from just any star.
Another image from NASA offers different detail:
NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the dying central star of this particular planetary nebula has become exceptionally hot, shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust. This sharp close-up of the dying star's nebula was recorded by the Hubble Space Telescope and is presented here in reprocessed colors. Cutting across a bright cavity of ionized gas, the dust torus surrounding the central star is near the center of this view, almost edge-on to the line-of-sight. Molecular hydrogen has been detected in the hot star's dusty cosmic shroud. NGC 6302 lies about 4,000 light-years away.
The hottest star type is O-type with a surface temperature of 30,000 to 60,000 K.
The central star's temperature is literally "off the chart" but no spectrum is provided to check how the extreme temperature was measured. It is odd this "dying star" overheats without exploding.
Everything in the butterfly nebula is plasma, with ions and protons capturing electrons to emit radiation at particular wave lengths.