Using the Atacama Large Millimeter/submillimeter Array or ALMA and the Karl G. Jansky Very Large Array, astronomers have captured a triple-star system in the middle of its birth.

Images taken by the ALMA telescope show two young stars forming in a spiral around an older star in the center of the stellar system, confirming a theory about how multiple stars form next to each other.

The theory posits that extra stars can form within the protoplanetary disk of another star. The disks are the by-products of clouds of gas and dust that form new stars.

A massive cloud may collapse in on itself and pull in more materials, causing the core to become denser and so hot it triggers the nuclear reaction that gives birth to a star.

Earlier studies suggested that multiple star systems are likely to have companion stars either relatively close or significantly farther apart. Astronomers believe that the difference in distances is the result of different formational mechanisms.

The more widely separated are formed when the larger cloud breaks into fragments through turbulence. Closer systems, on the other hand, are thought to be the result of fragmentation of the smaller disk that surrounds a young protostar.

Study researcher John Tobin, from the Leiden Observatory in the Netherlands, said the work supports the idea that two mechanisms can produce multiple star systems.

For their study, which was published in the journal Nature on Oct. 27, Tobin's team conducted a study of the newborn triple star system dubbed L1448 IRS3B, which lies in a cloud of gas in the constellation Perseus located about 750 light-years from Earth.

The bright star at the origin is separated from its two companions by 61 and 183 times the distance between the Earth and the sun. All of these stellar objects are surrounded by a disk of material with a spiral structure, a feature that astronomers consider as sign of disk instability.

The researchers said that the most widely separated of these stars may have formed only between 10,000 and 20,000 years ago. The system provided the astronomers with direct observational proof that fragmentation in the disk can give birth to young multiple star systems early in their development.

"We demonstrate that the disk around L1448 IRS3B appears susceptible to disk fragmentation at radii between 150 and 320 astronomical units, overlapping with the location of the tertiary protostar. This is consistent with models for a protostellar disk that has recently undergone gravitational instability, spawning one or two companion stars," the researchers wrote in their study.

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