A trespassing star flies past a growing young stellar pair

A trespassing star has been caught in the act of flying past a growing young stellar pair, in a detection made by ALMA (the Atacama Large Millimeter/submillimeter Array). Such stellar flybys have often been seen in computer simulations, but happen so quickly that no one has witnessed one taking place until now.

The flyby occurred in the Z Canis Majoris (Z CMa) binary star system, a young system only a few hundred thousand years old, which is still surrounded by its protostellar disc of dust. When the star flew past it pulled the debris disc out of shape, creating a chaotic stream of dust and gas. By analysing this pattern, the team were able to determine the intruder was an unrelated star, and not part of the same group as Z CMa.

“What we now know with this new research is that flyby events do occur in nature and that they have major impacts on the gaseous circumstellar discs surrounding baby stars, which are the birth cradles of planets,” says Nicolás Cuello from the Université Grenoble Alpes, who helped with the study. https://public.nrao.edu