For the first time, astronomers have discovered evidence of episodic development in young stars, witnessing these so-called growth spurts in CARMA-7—a protostar located 1,400 light years from Earth in a cluster known as Serpens South.
Adele Plunkett, a graduate of Yale University who is now working with the European Southern Observatory (ESO) in Chile, and her colleagues used the ESO’s Atacama Large Millimeter/sub-millimeter Array (ALMA) in Chile to record 22 “episodes” in which CARMA-7 experienced the gravitational push and pull characteristic of star formation.
As protostars take in raw materials, they emit other substances that are extraneous, Plunkett and her co-authors explained in a statement. This “outflow” can be detected much easier than the incoming matter, which makes it a good indicator of protostars, evolved stars, and even black holes, said co-author Héctor Arce, an astronomy professor at Yale.
Outflow found to begin early in protostar development
Outflows, he continued, “tell us that there is a central, massive object in the outflow origin, with a surrounding accretion disc.” Plunkett added that this is the first time that astronomers were able to observe individual outflows with distinct ejection events instead of just cumulative outflows.
She explained that this research was “something we could only do with ALMA,” as the telescope enabled the team to determine specific details about the star formation process. For instance, they observed how often material is either accreted or ejected, and additional observations could make it possible to observe protostars in their primary environment in even greater detail.
“This result shows that when young stars grow they do so episodically, in little growth spurts, rather than steadily,” explained Pieter van Dokkum, the Sol Goldman Professor of Astronomy, chair of Yale’s Department of Astronomy and one of the co-authors of the new study. “They’ve learned to chew their food before they swallow.”
“The data suggest that episodic, accretion-driven outflow begins in the earliest phase of protostellar evolution, and that the outflow remains intact in a very clustered environment, probably providing efficient momentum transfer for driving turbulence,” Plunkett’s team added.
The team published their findings in Nature.
—–
Feature Image: B. Saxton, NRAO/AUI/NSF; A Plunkett et al.; ALMA, NRAO/ESO/NAOJ
Comments