For the first time, astronomers have witnessed the birth of a multiple-star system and the observations could provide ground-breaking information about how these stellar systems form.
Scientists from a whole host of universities, including Manchester and Liverpool John Moores, have produced stunning images showing huge clouds of gas that are in the process of turning into stars.
The scientists focused on a cloud of gas roughly 800 light years from Earth. A particular section of the cloud already contains one young protostar, as well as three dense pockets of matter that are expected to collapse in on themselves within the next 40,000 years, forming stars. The team are optimistic that three of the eventual four stars may form a triple-star system.
Although the Sun has no stellar companions in our solar system, not all stars are found on their own. If two or more form from the same gas cloud, they will be bound by gravitational attraction and it is possible for them to orbit each other.
Binary pairs, which involve two stars, are the most common, although it is believed that systems containing as many as seven stars exist.
It is even possible for multiple-star systems to have planets orbiting them, although it is significantly more difficult for these to form. In 2012, two amateur astronomers discovered a Neptune-sized planet within the quadruple star system Kepler-64, the first of its kind to be observed.
The concept of planetary systems involving more than one star was perhaps best visualised in the Star Wars films, in which the planet Tatooine orbits a binary pair. One of the most iconic images from the series showed Luke Skywalker looking out at a double sunset.
Although many of the concepts illustrated in Star Wars are a tad unrealistic–I can’t imagine that there are many Death Stars floating around–multiple-star systems are actually remarkably common throughout the Universe.
While plenty of these systems have been observed, this recent discovery marks the first time that the creation of one has been witnessed.
Professor Gary Fuller of the University of Manchester’s Jodrell Bank Centre for Astrophysics said, “These kind of multi-star systems are quite common in the Universe. 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.”
The scientists used the VLA and GBT to observe a small area within the constellation Perseus. The zone in question was a dense core of gas called Barnard 5 (B5). It was already known that this area contained a young forming star.
Upon mapping radio emission from ammonia molecules in the cloud, the team realised that gas filaments in B5 are in the process of fragmenting. Some of these fragments are contracting to form new stars that may eventually join the current protostar in a multiple-star system.
The project leader, Dr Jaime Pineda of the Institute for Astronomy, ETH Zurich, said, “We know that these stars eventually will form a multi-star system because our observations show that these gas condensations are gravitationally bound.
“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.”
Several other mechanisms have been proposed for the creation of multiple-star systems, including gravitational capture, fragmentation of the main gas core and fragmentation within a disk of material orbiting a young star.
Dr Pineda concluded, “We’ve now convincingly added fragmentation of gas filaments to this list.”
The stars that are expected to form in B5 will range from roughly one-tenth to more than one-third the mass of the Sun. Their separations will be between 3,000 and 11,000 times the distance between the Earth and the Sun.
By analysing the dynamics of the condensations, the astronomers believe that when they collapse and form stars, a stable system of an inner binary pair will be produced. The other two stars are expected to be ejected from the system.
Don’t feel too sorry for them though. I’m sure Palpatine will find a use for them.
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