The three star system, with two young stars closer together and one further out.
[credit: B. Saxton (NRAO/AUI/NSF)]
ScienceDaily reports an unusual (to date) set-up involving three stars with a clear relationship in their average distances from each other. Quote: ‘The most central of the young stars is separated from the other two by 61 and 183 times the Earth-Sun distance’. The ratio of 61:183 is 1:3
For the first time, astronomers have seen a dusty disk of material around a young star fragmenting into a multiple-star system.
Scientists had suspected such a process, caused by gravitational instability, was at work, but new observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA) revealed the process in action.
“This new work directly supports the conclusion that there are two mechanisms that produce multiple star systems — fragmentation of circumstellar disks, such as we see here, and fragmentation of the larger cloud of gas and dust from which young stars are formed,” said John Tobin, of the University of Oklahoma and Leiden Observatory in the Netherlands.
Tobin, Kaitlin Kratter of the University of Arizona, and their colleagues used ALMA and the VLA to study a young triple-star system called L1448 IRS3B, located in a cloud of gas in the constellation Perseus, some 750 light-years from Earth.
The most central of the young stars is separated from the other two by 61 and 183 times the Earth-Sun distance. All three are surrounded by a disk of material that ALMA revealed to have spiral structure, a feature that, the astronomers said, indicates instability in the disk.
“This whole system probably is less than 150,000 years old.” Kratter said. “Our analysis indicates that the disk is unstable, and the most widely separated of the three protostars may have formed only in the past 10,000 to 20,000 years,” she added.
The L1448 IRS3B system, the astronomers conclude, provides direct observational evidence that fragmentation in the disk can produce young multiple-star systems very early in their development.
“We now expect to find other examples of this process and hope to learn just how much it contributes to the population of multiple stars,” Tobin said.
The scientists presented their findings in the October 27 edition of the journal Nature.
Full report: Young stellar system caught in act of forming close multiples — ScienceDaily
Talkshop note: Another question dating back to the so-called ‘Titius-Bode law‘ is whether distance ratios could play any part between other bodies of solar systems e.g. planets.