For more than 80 years, astrobods have a-pondered and a-peered at strange sets of dark bands that appear in the spectra of distant stars. These bands are entirely different from the absorption sepctra of specific ions, atoms and molecules which absorb light at specific, sharp frequencies. Instead these bands are broad and diffuse. And there are hundreds of ‘em.
Ain’t nobody got any idea what generates these so-called diffuse insterstellar bands. Astrobods assume that something in interstellar space is absorbing the light in these bands, perhaps dust, perhaps ice or perhaps complex oranic molecules such as polyaromatic hydrocarbons. A number of groups have tried to reproduce the absorption spectra in labs in Earth but all have failed miserably. So the origin of DIBs remains a mystery.
It seems clear, however, that a number of different things must be behind DIBs cos if one species of interstellar stuff were responsible it would have to be fiendishly complex.
So alotta interesting questions remain unanswered. Why are DIBs diffuse and not sharp like other absorption spectra? Why so many? And (obviously) what’s causing them?
All this talk of DIBs is brought on by a light and rather bland review of the topic by Bogdan “Dobs” Wszolek at the Institute of Physics in Poland. If you want a quick intro (it’s just three pages), give it a scan.
Ref: arxiv.org/abs/0712.1553: Puzzling Phenomenon of Diffuse Interstellar Bands