by mollwollfumble » Sun Jan 31, 2016 10:18 am
> A leading progenitor hypothesis for the square nebula ...
The red square nebula is not at all well understood. The reason for this is the physical and spectroscopic similarity to the red rectangle nebula, which is not understood at all. The spectrum of light arriving at Earth absorbed by the interstellar medium contains absorption lines from "diffuse interstellar bands". Continual research into the spectrum of diffuse interstellar bands has not reached anything like a consensus, with umpteen possibilities including modified buckyballs, unusual anthracenes and metal-organic dust grains. Searches for similar spectra elsewhere found only one match - the red rectangle. That makes the red rectangle unique, definitely not similar to other planetary nebulae. The red square also shares spectral details with the red rectangle, which makes it the second closest match to the "diffuse interstellar bands".
As a result, the red square should not be considered to be closely related to other planetary nebulae, it's too weird.
> A leading progenitor hypothesis for the square nebula ...
The red square nebula is not at all well understood. The reason for this is the physical and spectroscopic similarity to the red rectangle nebula, which is not understood at all. The spectrum of light arriving at Earth absorbed by the interstellar medium contains absorption lines from "diffuse interstellar bands". Continual research into the spectrum of diffuse interstellar bands has not reached anything like a consensus, with umpteen possibilities including modified buckyballs, unusual anthracenes and metal-organic dust grains. Searches for similar spectra elsewhere found only one match - the red rectangle. That makes the red rectangle unique, definitely not similar to other planetary nebulae. The red square also shares spectral details with the red rectangle, which makes it the second closest match to the "diffuse interstellar bands".
As a result, the red square should not be considered to be closely related to other planetary nebulae, it's too weird.