Most exoplanets might be 'soot factories,' scientists say: 'Like you have a natural diesel engine'

Vast clouds of soot that form in the pressure cooker of mysterious mini-Neptune exoplanets may hold the truth about these worlds' origins. "It's like you have a natural diesel engine in the deep atmosphere of a planet," lead author of a study about this research, Jeehyun Yang of the University of Chicago, said in a statement . Yang did his Ph.D. in chemical engineering, studying the exhausts of combustion engines before transitioning to study the chemistry of exoplanet atmospheres. The exhaust fumes of diesel engines are filled with black smoke made up of honeycomb-shaped particles called PAHs — polycyclic aromatic hydrocarbons. PAHs are among the most common carbon-based compounds in the cosmos, and are frequently produced whenever we burn something. (That black char on your burned toast? That's made of PAHs too.) When it comes to chemistry, some exoplanet atmospheres are more enigmatic. Take the mini- Neptunes — worlds in the size range between Earth and Neptune that are found orbiting close to their star . Despite their being the most common type of exoplanet found so far, debate continues to rage over the nature of these mid-size worlds. …