Thanks to the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have been able to witness an adolescent star (protostar) undergoing several quick growth spurts. The team has observed a pair of intermittent polar jets, indicating the protostar has been gaining material at regular intervals.
The latest observation shows 22 distinct jet emissions from the protostar, which have regularly happened about every 100 years. The outflows have traveled for a quarter of a light-year (2.46 trillion kilometers, 1.53 trillion miles), and they are now interacting with the jets of other protostars and the interstellar clouds.
The young star is called CARMA-7, and it was first discovered by the Combined Array for Research in Millimeter-wave Astronomy (CARMA) telescope. It is part of the Serpens South star cluster, which is a close-knit group of 35 protostars and 15 full-grown stars. It is located over 1,350 light-years from Earth in the constellation of the snake (Serpens).
"This young protostar is undergoing periods of rapid growth separated by periods of relative calm," said Adele Plunkett, lead author of the research, in a statement. "This punctuated stellar formation provides important insights into the chaotic interplay within this tightly packed cluster of young stars."
Stars form in large clouds of gas and dust. These clouds tend to break down into smaller and smaller interacting pieces until the fragments become small and dense enough to collapse into stars. A protostar forms from these fragments. As the spinning star evolves, it squishes material from the cloud into a disk, which continues to accrete onto the nascent star.
When protostars eat material from the disk, some of it is shot out from the poles of the star due to the star's strong magnetic fields and other dynamical effects. The ejected mass is of the order of one to 20 Earth-masses, a minuscule amount compared to the mass of the protostar, and it moves at several hundred kilometers per second.
A paper describing the results in detail has been published in Nature.