Brian Koberlein, Author at Universe Today

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.

August 15, 2021August 15, 2021 by Brian Koberlein

If the First Black Holes Collapsed Directly, Could we Detect Radio Signals From Those Moments?

This artist’s impression shows a possible seed for the formation of a supermassive black hole. Credit: NASA/CXC/M. Weiss

The universe is littered with supermassive black holes. There’s one a mere 30,000 light-years away in the center of the Milky Way. Most galaxies have one, and some of them are more massive than a billion stars. We know that many supermassive black holes formed early in the universe. For example, the quasar TON 618 is powered by a 66 billion solar mass black hole. Since its light travels nearly 11 billion years to reach us, TON 618 was already huge when the universe was just a few billion years old. So how did these black holes grow so massive so quickly?

August 14, 2021August 14, 2021 by Brian Koberlein

Matter From Light. Physicists Create Matter and Antimatter by Colliding Just Photons.

An artistic view of light becoming matter. Credit: Gerd Altmann, via Pixabay

In 1905 Albert Einstein wrote four groundbreaking papers on quantum theory and relativity. It became known as Einstein’s annus mirabilis or wonderous year. One was on brownian motion, one earned him the Nobel prize in 1921, and one outlined the foundations of special relativity. But it’s Einstein’s last 1905 paper that is the most unexpected.

August 11, 2021August 11, 2021 by Brian Koberlein

Astronomers Find a Nearby Star That a Spitting Image of a Young Sun

Illustration of what the Sun may have been like 4 billion years ago. Credit: NASA's Goddard Space Flight Center/Conceptual Image Lab

Our Sun is about 4.6 billion years old. We know that from models of Sun-like stars, as well as through our observations of other stars of similar mass. We know that the Sun has grown hotter over time, and we know that in about 5 billion years it will become a red giant star before ending its life as a white dwarf. But there are many things about the Sun’s history that we don’t understand. How active was it in its youth? What properties of the young Sun allowed life to form on Earth billions of years ago?

August 7, 2021August 7, 2021 by Brian Koberlein

Good News! Red Dwarfs Blast Their Superflares out the Poles, Sparing Their Planets From Destruction

The only known life in the universe lives on a mid-size rocky planet that orbits a mid-size yellow star. That makes our planet a bit unusual. While small rocky planets are common in the galaxy, yellow stars are not. Small red dwarf stars are much more typical, making up about 75% of the stars in the Milky Way. This is why most of the potentially habitable exoplanets we’ve discovered orbit red dwarfs.

July 25, 2021July 25, 2021 by Brian Koberlein

A Gravitational Wave Observatory on the Moon Could "Hear" 70% of the Observable Universe

Concept for a Gravitational-wave Lunar Observatory for Cosmology (GLOC). Credit: Jani, et al

Gravitational-wave astronomy is set to revolutionize our understanding of the cosmos. In only a few years it has significantly enhanced our understanding of black holes, but it is still a scientific field in its youth. That means there are still serious limitations to what can be observed.