Asteroids with organic matter form in cool places

Australian scientists have analyzed the chemical composition of samples from the Ryugu asteroid and the Murchison meteorite. They determined which isotopes are included in organic compounds called polycyclic aromatic hydrocarbons and concluded that at least some of them were formed in the interstellar medium.

Астероїди та органічні речовини в них утворилися в міжзоряному просторі
Asteroids and the organic substances in them were formed in interstellar space. Source:

Aromatic hydrocarbons in asteroids and meteorites

Researchers have proved long ago that the chemical composition of asteroids and meteorites are very similar, indicating that they have a common origin. In addition, they contain quite similar organic compounds. And recently, Australian scientists have established the conditions under which they were formed.

Scientists from the Curtin’s Center for Organic and Isotopic Geochemistry examined samples from the Ryugu asteroid and the Murchison meteorite. The former was recently brought back by the Japanese space probe Hayabusa-2. The latter fell to Earth in Australia in 1969.

Scientists are particularly interested in organic molecules called polycyclic aromatic hydrocarbons. They consist of several rings that are connected together. These substances have recently been found quite often in space. And now scientists have determined the conditions under which they are formed.

Asteroids are formed in interstellar space

In order to find out exactly where the asteroids and organic molecules in them were formed, the researchers subjected the samples to spectral and isotopic analyzes. They calculated the conditions under which certain types of atoms should have been formed, and then looked at which of them were present in the molecules.

The most remarkable thing is that even within a single sample there are strong irregularities in the composition of the stones. Some of the grains that make up the asteroids were clearly formed in cooler conditions than they are now.

And “colder” does not mean that they were farther from the Sun than the Earth at that time. It means that they were formed somewhere in interstellar space, far from any luminary. However, the rest of the molecules were clearly formed in much warmer conditions.

This is of great importance for our understanding of life in the Universe. Apparently, the formation of the simplest organic models is possible without the participation of sunlight at all, so the whole Universe is literally dotted with “bricks of life.” But in order to “mature” they need the same conditions as for the formation of Earth-like planets.

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