There's a monstrous hole in the universe. Long ago, a star blew up with extreme force and obliterated everything in its path. It even swept minuscule particles of space dust out of its way -- but in a surprising turn of events, that space dust collected, collapsed and eventually gave birth to a bunch of baby stars.
As the saying goes, it's the circle of life.
"That is something that has been suggested in theory, and also seen in numerical simulations, but now we think we see it for the first time in observations," said lead author Shmuel Bialy, an astrophysicist at the Institute for Theory and Computation at the Harvard Smithsonian Center for Astrophysics.
The story starts with a many-million-years-old, 500-light-year-wide spherical void lurking in outer space. To be clear, this completely vacant cavity is absolutely huge. One light-year is about 6 trillion miles (9 trillion kilometers), which means the void could fit 150,000 versions of our solar system within it.
Mysterious, seemingly abrupt cavities like this one are sometimes detected in the cosmos. They're just sudden holes of empty space. But because astronomers typically study space in two dimensions -- with spectrum data, or even photographs -- three-dimensional structures can be tricky to find. Even when astronomers do locate them, it can be rather difficult to understand what's going on.
"There's a lot of confusion along the line of sight," Bialy said. "You don't know the distance, so sometimes we see different structures and they just look like one structure -- or the opposite."
Bialy's team solved the problem by harnessing a new power: augmented reality.
They re-created a mini-version of the gigantic space-borne cavity, as well as the stuff that surrounds it. Then they toyed with their model in real time to unlock the elusive void's secrets. A QR code to the masterpiece is included in their paper, published Wednesday in The Astrophysical Journal Letters. There's also a demo on YouTube.
Basically, you can download their reconstructed piece of space onto your phone and feel as though it's in your room. "It's almost like in the movies where you have a hologram," Bialy said.
While surveying their digital sculpture for research purposes -- as opposed to the frivolous fun I had while spinning the projection around on my coffee table -- the team saw an unusual "shell" of material around a symmetrical, abandoned area: the giant cavity.
They concluded that a nearly 10-million-year-old star explosion -- or multiple star explosions over the timespan -- pushed away particles in the vicinity, thus making a capsule of space dust encircling an uninhabited region of space.
"Imagine … you have lots of dust from the floor," Bialy explained. "You have a big room, and you just sweep up some of the dust into one region -- now, in this region … you have a much higher density of dust."
When space dust clumps together, it's known to collapse and compact itself more easily. But perhaps the most surprising discovery is that two famous clouds, Perseus and Taurus, which pop out baby stars like a stellar factory, live in that shell of dust.
"They were traditionally thought to be just two independent clouds," Bialy said. "Now with this three-dimensional view and the discovery of this cavity, we understand that they probably formed together by the action of a supernova explosion that preceded them."
That means star explosions might be setting off a chain reaction that ultimately leads to the creation of their own descendants.
"I wouldn't say this is the only way to form clouds that form stars, but this is a viable way," Bialy said.
Bialy's entire project initially began as an examination of the Perseus molecular cloud alone. The researchers were trying to understand star formation and gaps within the small region of space in 2D. While looking at the images, they started noticing little "shells" within Perseus.
So, they started zooming out… then again… and again.
"We enlarged the map," Bialy explained. "We started seeing larger and larger shells until, finally, this huge shell."
On top of encouraging the public to see the magic for themselves, by scanning the QR code and exploring the model, Bialy says, the team also released their numerical data in its entirety to the public. That ensures transparency so anyone can attempt to draw the same conclusions the team arrived at, but from scratch, if they so desire.
Beyond the remarkable findings about how stars, and star clouds, could be produced, Bialy stresses that the use of new perspectives and methodologies in astrophysics could be paving the way for the subject's future.
"I used to just do the science," Bialy said. "Suddenly, I'm working with this augmented reality company and an animator and different people."
AR, specifically, promises a much richer library of scientific literature. Instead of a thick set of encyclopedias, we'd turn to digital holograms that can be called on at will.