Enlarge / If a star (red trail) wanders too close to a black hole (left), it can be shredded, or spaghettified, by the intense gravity. Some of the star’s matter swirls around the black hole, like water down a drain, emitting copious X-rays (blue). (credit: NASA/CXC/M. Weiss)

When astronomers first observed a star that was shredded, or “spaghetified,” after approaching too close to a massive black hole in 2019, they determined that much of the star’s matter was launched outward in a powerful wind from the optical light emitted from the blast. Now, astronomers from the University of California, Berkeley (UCB) have analyzed the polarization of that light to determine that the cloud was likely spherically symmetric, adding further evidence for the presence of that powerful wind.

“This is the first time anyone has deduced the shape of the gas cloud around a tidally spaghetiffied star,” said co-author Alex Filippenko , a UCB astronomer. The latest findings appeared in a recent paper published in the Monthly Notices of the Royal Astronomical Society.

As we've reported previously , an object that passes beyond the event horizon of a black hole—including light—is swallowed up and can't escape, although black holes are also messy eaters. That means that part of an object's matter is actually ejected out in a powerful jet. If that object is a star, the process of being shredded (or "spaghetified") by the powerful gravitational forces of a black hole occurs outside the event horizon, and part of the star's original mass is ejected violently outward. This can form a rotating ring of matter (aka an accretion disk ) around the black hole that emits powerful X-rays and visible light. The jets are one way astronomers can indirectly infer the presence of a black hole.

Produced and directed by Corey Eisenstein. Click here for transcript . (video link)

Ars' Edge of Knowledge series looks at important aspects of our Universe that we still understand poorly, like dark matter and the origin of life. This week, our host Paul Sutter bravely ventures into the area we probably understand the least: dark energy. Dark energy accounts for about 75 percent of the stuff in the Universe, but we still don't have even the slightest idea what it is and are a bit stumped as to how to even go about finding out.

Paul goes into how we accidentally discovered that the Universe's expansion is accelerating when astronomers looked for an indication that the expansion was slowing down. Dark energy is simply the term we're using for the big unknown here: What's driving that acceleration?

Black holes feeding on companion stars can go through cycles where they emit high-energy outbursts. MIT astronomers are using X-ray echoes from those cycles to map out the environment around these exotic objects, similar to how bats map out their environment via echolocation. The astronomers hope to use this new data to learn more about the evolution of these kinds of black hole systems, and by extension, the formation of galaxies, according to a new paper published in the Astrophysical Journal.

“The role of black holes in galaxy evolution is an outstanding question in modern astrophysics,” said co-author Erin Kara of MIT. “These black hole binaries appear to be ‘mini’ supermassive black holes, and so by understanding the outbursts in these small, nearby systems, we can understand how similar outbursts in supermassive black holes affect the galaxies in which they reside.”

As we've reported previously , it's a popular misconception that black holes behave like cosmic vacuum cleaners , ravenously sucking up any matter in their surroundings. In reality, only stuff that passes beyond the event horizon—including light—is swallowed up and can't escape, although black holes are also messy eaters. That means that part of an object's matter is ejected in a powerful jet.