The barred spiral galaxy M 83, Southern Pinwheel. The white spot in the middle is the "beam". (Source: Anglo-Australian Observatory)
In the beam of the spiral galaxy M 83, also called "Southern Wheel of Fire", stars are born in a kind of domino effect. This concludes an international team of astronomers from spectral studies of light from the beam of M 83. The observations were made at the Gemini Observatory in Chile. "A detailed analysis is still in progress, but our initial results suggest a complex sequence of star formation, " report Robert Sharp, Ian Parry of Cambridge University and their colleagues. They believe that the rotation of gas and stars in the central beam of the galaxy dictates a particular order of star formation. The astronomers thus contradict a theory that assumes a random star formation in the center of M 83.

From the spectral lines of light one can infer the chemical elements in the stars. Each chemical element emits its own specific "fingerprint" on spectral lines or filters out spectral lines from the light spectrum. With the new spectrograph CIRPASS the astronomers searched specifically for certain lines.

In particular, they were interested in the so-called Paschen beta line of hydrogen, which is emitted by young hot stars. The electron of the hydrogen atom can assume a variety of energy states. It can be thought of as the electron can orbit around the atomic nucleus on different orbits in different "heights". When jumping onto another track, a characteristic light radiation is emitted.

By comparing it to a particular spectral line absorbed by carbon monoxide found in the cold atmospheres of ancient giant stars, astronomers were able to deduce the age structure of the stars. display

Axel Tilleman

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