A multiple star system in its infancy has been spotted by astronomers for the first time, according to a press release from the National Radio Astronomy Observatory.
Scientists monitored a core of gas located about 800 light-years away from Earth that contains one protostar and three dense condensations that are expected to collapse in 40,000 years - a short time, astronomically. Astronomers foresee three of the four future stars becoming a triple-star system.
"These kind of multi-star systems are quite common in the universe," said Gary Fuller, a professor at the Jodrell Bank Center for Astrophysics, The University of Manchester. "Think of Tatooine in Star Wars, where there are two 'suns' in the sky. That isn't too far away from something that could be a real formation. In fact nearly half of all stars are in this type of system."
"Seeing such a multiple star system in its early stages of formation has been a longstanding challenge, but the combination of the Very Large Array (VLA) and the Green Bank Telescope (GBT) has given us the first look at such a young system," said Jaime Pineda, of the Institute for Astronomy, ETH Zurich, in Switzerland.
The VLA and GBT were used along with the James Clerk Maxwell Telescope (JCMT) in Hawaii in the study of the gas core, called Barnard 5 (B5) in the constellation Perseus.
Radio emissions from methane in the gas cloud were mapped by the VLA, and fragmenting in B5 was uncovered. The fragments are what will become the new stars.
"We know that these stars eventually will form a multi-star system because our observations show that these gas condensations are gravitationally bound," Pineda said, according to the press release. "This is the first time we've been able to show that such a young system is gravitationally bound."
"This provides fantastic evidence that fragmentation of gas filaments is a process that can produce multiple-star systems," Pineda continued. Other proposed mechanisms include fragmentation of the main gas core, fragmentation within a disk of material orbiting a young star, and gravitational capture. "We've now convincingly added fragmentation of gas filaments to this list."
The stars in B5 are predicted to range from one-tenth to more than one-third the mass of our Sun and will have between 3,000 to 11,000 times the Earth-Sun distance between them.
"Nearly half of all stars are in multiple systems, but catching such systems at the very early stages of formation has been challenging," Pineda said, according to the press release. "Thanks to the combination of the VLA and the GBT, we now have some important new insight into how multiple systems form. Our next step will be to look at other star-forming regions using the new capabilities of the VLA and of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile."
"It seems like a simple question," said astrophysicist Stella Offner in a press release from the University of Massachusetts Amherst. "Why is our sun a single star while the nearest star to us, Alpha Centauri, happens to be a triple system? There are competing models for how multiple star systems are born, but now we know a little more than we did before."
"In terms of what this means for the formation of our sun," she added, "it suggests that its early conditions did not look like this forming system. Instead, the sun likely formed from something that was more spherical than filamentary. The distribution of the planets in our solar system also suggests that our sun was never part of a multiple system like this one."
The international research team, with additional members in Germany and Chile, reported their findings in the journal Nature.
