Astronomers discover an empty cavity carved into space by a violent explosion


A supernova explosion could have created a hole in the universe.

ESO / SpaceEngine / L. Street

There is a monstrous hole in the universe. A long time ago a star exploded with extreme force, obliterating everything in its path. It even swept tiny particles of space dust out of the way – but in a surprising twist, that space dust gathered, collapsed, and eventually gave birth to a bunch of baby stars.

As the saying goes, it is the cycle of life.

“That was suspected in theory and seen in numerical simulations, but now we believe we are seeing it for the first time in observations,” said lead author Shmuel Bialy, an astrophysicist at the Harvard Smithsonian Center for Astrophysics Institute of Theory and Computers.

The story begins with a million-year-old, 500 light-year wide spherical void lurking in space. To be clear, this completely empty cavity is absolutely huge. A light year is roughly 9 trillion kilometers, which means the void could hold 150,000 versions of our solar system in it.

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Mysterious, seemingly abrupt cavities like this one are sometimes discovered in the cosmos. They are just sudden holes in empty space. But since astronomers usually study space in two dimensions – using spectral data or even photos – three-dimensional structures can be difficult to find. Even when astronomers pinpoint them, understanding what is going on can be quite difficult.

“There’s a lot of confusion along the line of sight,” said Bialy. “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 have recreated a mini version of the gigantic space cavity as well as the material that surrounds it. Then they played with their model in real time to unlock the secrets of the elusive void. A QR code for the masterpiece is included in their article published in The Astrophysical Journal Letters on Wednesday. There is also a demo on YouTube.

Basically, you can download your reconstructed piece of space onto your phone and feel like it’s in your room. “It’s almost like the movies where you have a hologram,” said Bialy.

While examining their digital sculpture for research purposes – as opposed to the frivolous fun I had while rotating the projection on my coffee table – the team saw an unusual “shell” of material around a symmetrical, deserted area: the huge cavity.

They concluded that a stellar explosion nearly 10 million years old – or several stellar explosions over time – pushed away particles nearby, creating a capsule of space dust that surrounds an uninhabited region of space.

“Imagine … you have a lot of dust on the floor,” Bialy explained. “You have a large space and only sweep some of the dust into a region – now you have in that region … a much higher density of dust.”

When space dust clumps together, it has been known to collapse and compact itself more easily. But perhaps the most surprising discovery is that in this cover of dust live two famous clouds, Perseus and Taurus, which, like a star factory, produce baby stars.

“Traditionally, it was thought they were just two independent clouds,” said Bialy. “With this three-dimensional view and the discovery of this cavity, we now understand that they were likely formed together by the action of a supernova explosion that preceded them.”

This means that star explosions could set off a chain reaction that ultimately leads to the creation of its own offspring.

“I wouldn’t say this is the only way to create clouds that will form stars, but it is a workable way,” Bialy said.

milky way-zoom-in.png

An enlarged view of the cavity (left) shows the Perseus and Taurus molecular clouds in blue and red, respectively.

Alyssa Goodman / Center for Astrophysics | Harvard & Smithsonian.

Bialy’s entire project initially began solely with the study of the Perseus molecular cloud. The researchers tried to understand star formation and gaps within small space in 2D. When looking at the pictures, they noticed small “shells” in Perseus.

So they started zooming out … then again … and again.

“We have enlarged the map,” explained Bialy. “We started to see bigger and bigger clams, until finally this huge clam.”

Bialy says the team is not only encouraging the public to see the magic for themselves by scanning the QR code and examining the model, but also making all of their numerical data available to the public. This ensures transparency so that everyone can try to draw the same conclusions the team came to, but from scratch, if they so choose.

Aside from the remarkable insights into how stars and star clouds could be created, Bialy emphasizes that the use of new perspectives and methods in astrophysics could pave the way for the future of the subject.

“I used to just do science,” said Bialy. “All of a sudden, I’m working with this augmented reality company and an animator and different people.”

In particular, AR promises a much richer library of academic literature. Instead of a long set of encyclopedias, we would turn to digital holograms that can be accessed at will.


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