Star systems form in dense, cold regions within giant molecular clouds, vast reservoirs of hydrogen and assorted elements and molecules. There are many complex processes going on in these clouds and for the first time, astronomers have observed a literal conveyor belt of gas moving from the mother cloud on the outskirts of a dense star-forming region to a pair of baby stars.
Reported in Nature Astronomy, the researchers tracked the gas “streamer” (as it is called) from near the two stars all the way out to about a light-day away, roughly 10,500 times the Earth-Sun distance. The findings suggest that gas from the cloud flows all the way down to the disk of material that surrounds these infant stars.
The observed streamer is around a system called Per-emb-2 (IRAS 03292+3039) in the Perseus molecular cloud, roughly 1,000 light-years away.
The observations of both location and speed of the gas streamer match well with theoretical models that suggest this material is simply in free-fall towards the densest regions where stars are born. The researchers were also surprised by its size, somewhere between 0.1 to 1 times the mass of the Sun. By comparison, the densest part of these clouds is about three times the mass of the Sun.
“The streamer must indeed bring in chemically fresh material from the outer regions on a relatively short timescale,” lead author Dr Jaime Pineda, from the Max Planck Institute for Extraterrestrial Physics (MPE), said in a statement. “The clear identification of such a large reservoir of fresh material in almost free-fall is remarkable.”
To observe the motion of this material researchers tracked several different molecules including some carbon-rich ones. The arrival of such a large amount of material so chemically rich will have a major impact on the system in more ways than one.
“The chemical composition of the growing and evolving protoplanetary disks will also be affected by this new phenomenon,” explained Dr Paola Caselli, director at MPE and part of the team. “The molecule which allowed us to discover the streamer has three carbon atoms (HCCCN), which will then be available to enrich organic chemistry (on its way toward pre-biotic compounds) during the phase of planet assembly.”
The observations provide important insights on how planetary systems might form, but many more observations are necessary to have a complete picture.
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