Brian Koberlein, Author at Universe Today

September 25, 2021September 25, 2021 by Brian Koberlein

Astronomers Find a Giant Cavity in Space, Hollowed out by an Ancient Supernova

A cavity of empty space was likely caused by a supernova. Credit: Alyssa Goodman/Center for Astrophysics | Harvard & Smithsonian

Star formation is a topic astronomers are still trying to fully understand. We know, for example, that stars don’t form individually, but rather are born within vast interstellar molecular clouds. These stellar nurseries contain gas dense enough for gravity to trigger the formation of stars. In spiral galaxies, these molecular clouds are most commonly found within spiral arms, which is why stars are most often born in spiral arms.

September 18, 2021September 18, 2021 by Brian Koberlein

Finally an Answer to why Gamma Rays are Coming From Seemingly Empty Space

The cosmic glow of the gamma ray background. Credit: NASA/DOE/Fermi LAT Collaboration

Gamma rays strike Earth from all directions of the sky. Our planet is bathed in a diffuse glow of high-energy photons. It doesn’t affect us much, and we don’t really notice it, because our atmosphere is very good at absorbing gamma rays. It’s so good that we didn’t notice cosmic gamma rays until the 1960s when gamma-ray detectors were launched into space to look for signs of atomic weapons tests. Even then, what we noticed were intense flashes of gamma rays known as gamma ray bursts.

September 14, 2021September 14, 2021 by Brian Koberlein

We Knew Black Holes Have a Temperature. It Turns out They Also Have a Pressure

Artist view of an active supermassive black hole. Credit: ESO/L. Calçada

In the classical theory of general relativity, black holes are relatively simple objects. They can be described by just three properties: mass, charge, and rotation. But we know that general relativity is an incomplete theory. Quantum mechanics is most apparent in the behavior of tiny objects, but it also plays a role in large objects such as black holes. To describe black holes at a quantum level, we need a theory of quantum gravity. We don’t have a complete theory yet, but what know so far is that quantum mechanics makes black holes more complex, giving them properties such as temperature and perhaps even pressure.

September 12, 2021September 12, 2021 by Brian Koberlein

Researchers Generate an Entire Virtual Universe and Make it Available for Download (if you Have 100 Terabytes of Free Hard Drive Space)

The distribution of dark matter in the Uchuu simulation. Credit: Tomoaki Ishiyama

Astronomy is a bit different from many sciences because you only have a sample size of 1. The cosmos contains everything we can observe, so astronomers can’t study multiple universes to see how our universe ticks. But they can create computer simulations of our universe. By tweaking different aspects of their simulation, astronomers can see how things such as dark matter and dark energy play a role in our universe. Now, if you are willing to spring for a fancy hard drive, you can keep one of these simulations in your pocket.

September 4, 2021September 4, 2021 by Brian Koberlein

Heavier Stars Might not Explode as Supernovae, Just Quietly Implode Into Black Holes

An artist view of how a star can collapse directly into a black hole. Credit: NASA, ESA, and P. Jeffries (STScI)

A supernova is a brilliant end to a giant star. For a brief moment of cosmic time, a star makes one last effort to keep shining, only to fade and collapse on itself. The end result is either a neutron star or a stellar-mass black hole. We’ve generally thought that all stars above about ten solar masses will end as a supernova, but a new study suggests that isn’t the case.

September 1, 2021July 12, 2022 by Brian Koberlein

Brown Dwarfs are Probably Much More Common in the Milky Way Than Previously Believed

Brown dwarfs are too big to be planets, but not quite massive enough to be stars. Credit: NASA/JPL-Caltech

Brown dwarfs are strange things. They are in the middle ground between planets and stars. A star is defined as an object massive enough for hydrogen to fuse into helium into its core, while a planet is too small for core fusion to occur. It seems a simple distinction until you learn about fusion. Anything with a mass below about 13 Jupiters is too small for fusion to occur, and is thus a planet. If your mass is about about 80 Jupiters, then you can fuse helium and are therefore a star. But if your mass is between 13 and 80 Jupiters, things get interesting. You can’t fuse hydrogen to shine brightly, but you can fuse lithium into other elements. This is known as lithium burning. It doesn’t provide lots of energy, but it is technically nuclear fusion.

August 28, 2021August 28, 2021 by Brian Koberlein

If Planet 9 is out There, Here's Where to Look

Illustration of the hypothetical Planet 9. Credit: R. Hurt/IPAC, Caltech

There are eight known planets in the solar system (ever since Pluto was booted from the club), but for a while, there has been some evidence that there might be one more. A hypothetical Planet 9 lurking on the outer edge of our solar system. So far this world has eluded discovery, but a new study has pinned down where it should be.

August 26, 2021August 26, 2021 by Brian Koberlein

Interstellar Objects Might Outnumber Solar System Objects in the Oort Cloud

Artist’s impression of the interstellar object, `Oumuamua, experiencing outgassing as it leaves our Solar System. Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

Our solar system is filled with everything from planets to rocky asteroids to small icy bodies beyond Pluto, but surrounding all of it is a diffuse halo of objects known as the Oort cloud. We haven’t directly observed the Oort cloud, but we’re pretty sure it’s there by observing the distribution of comet in our solar system. They can appear from any direction in the sky rather than just along the common plane of known solar system bodies.

August 21, 2021August 21, 2021 by Brian Koberlein

The Milky Way Broke one of its Arms

A contingent of stars and star-forming clouds was found jutting out from the Milky Way's Sagittarius Arm. Credit: NASA/JPL-Caltech

The Milky Way galaxy is our home, and yet in some ways, it is the least understood galaxy. One of the biggest challenges astronomers have is in understanding its large-scale structure. Because we’re in the midst of it all, mapping our galaxy is a bit like trying to map the size and shape of a wooded park while standing in the middle of it.

August 18, 2021August 18, 2021 by Brian Koberlein

You can Tell how big a Black Hole is by how it Eats

An artist’s impression of an accretion disk rotating around an unseen supermassive black hole. Credit: Mark A. Garlick/Simons Foundation

Black holes don’t emit light, which makes them difficult to study. Fortunately, many black holes are loud eaters. As they consume nearby matter, surrounding material is superheated. As a result, the material can glow intensely, or be thrown away from the black hole as relativistic jets. By studying the light from this material we can study black holes. And as a recent study shows, we can even determine their size.