Brian Koberlein, Author at Universe Today

September 23, 2024September 23, 2024 by Brian Koberlein

Those Aren't Dyson Spheres, They're HotDOGs

Imagining the Universe as a collection of stellar bubbles. Credit: NASA

If there really are advanced alien civilizations out there, you’d think they’d be easy to find. A truly powerful alien race would stride like gods among the cosmos, creating star-sized or galaxy-sized feats of engineering. So rather than analyzing exoplanet spectra or listening for faint radio messages, why not look for the remnants of celestial builds, something too large and unusual to occur naturally?

September 22, 2024September 22, 2024 by Brian Koberlein

Researchers Mimic Extracting Energy From Black Holes in the Lab

Illustration of a rapidly rotating black hole. Credit: ESO, ESA/Hubble, M. Kornmesser

When you get close to a black hole, things can get pretty intense. The tremendous gravity can squeeze gas to ionizing temperatures, and fierce magnetic fields can accelerate plasma into jets speeding at nearly the speed of light. That’s a lot of power, and wherever there is power someone will figure out how to harness it.

September 20, 2024September 20, 2024 by Brian Koberlein

Could Stars Hotter Than the Sun Still Support Life?

A comparison of typical sizes of main sequence stellar classes. Credit: NASA’s Goddard Space Flight Center

Although most potentially habitable worlds orbit red dwarf stars, we know larger and brighter stars can harbor life. One yellow dwarf star, for example is known to have a planet teaming with life, perhaps even intelligent life. But how large and bright can a star be and still have an inhabited world? That is the question addressed in a recent article in the Astrophysical Journal.

September 19, 2024September 19, 2024 by Brian Koberlein

Exoplanets Could be Hiding Their Atmospheres

Illustration of the tidally locked world TRAPPIST-1f. Credit: NASA/JPL-Caltech

Most of the exoplanets we’ve discovered orbit red dwarf stars. This isn’t because red dwarfs are somehow special, simply that they are common. About 75% of the stars in the Milky Way are red dwarfs, so you would expect red dwarf planets to be the most abundant. This also means that most habitable worlds are going to orbit these small, cool stars, and that has some significant consequences for our search for life.

September 18, 2024September 18, 2024 by Brian Koberlein

SETI Scientists Scan TRAPPIST-1 for Technosignatures

Three of the TRAPPIST-1 planets – TRAPPIST-1e, f and g – dwell in their star’s so-called “habitable zone. CreditL NASA/JPL

If you are going to look for intelligent life beyond Earth, there are few better candidates than the TRAPPIST-1 star system. It isn’t a perfect choice. Red dwarf stars like TRAPPIST-1 are notorious for emitting flares and hard X-rays in their youth, but the system is just 40 light-years away and has seven Earth-sized worlds. Three of them are in the potentially habitable zone of the star. They are clustered closely enough to experience tidal forces and thus be geologically active. If intelligent life arises easily in the cosmos, then there’s a good chance it exists in the TRAPPIST-1 system.

September 17, 2024September 17, 2024 by Brian Koberlein

Could We Find Primordial Black Holes in the Solar System?

An artistic take on primordial black holes. Credit: NASA’s Goddard Space Flight Center

Astronomers have observed three types of black holes in the Universe. Stellar-mass black holes formed from the collapse of a massive star, intermediate mass black holes found in some star clusters, and supermassive black holes that lurk in the centers of galaxies. But there is a fourth type that remains hypothetical an unobserved. Known as primordial black holes, they are thought to have formed from tiny fluctuations in the hot and dense early cosmos. Since they wouldn’t have formed from stars or mergers, they could have a much smaller mass. And with small masses, primordial black holes would be tiny. Their event horizons would be smaller than an apple, perhaps as small as a grain of sand. You can see why they would be hard to find.

May 11, 2024May 11, 2024 by Brian Koberlein

Supermassive Black Holes Got Started From Massive Cosmic Seeds

The J0148 quasar circled in red. Two insets show, on top, the central black hole, and on bottom, the stellar emission from the host galaxy. Credit: NASA

Supermassive black holes are central to the dynamics and evolution of galaxies. They play a role in galactic formation, stellar production, and possibly even the clustering of dark matter. Almost every galaxy has a supermassive black hole, which can make up a small fraction of a galaxy’s mass in nearby galaxies. While we know a great deal about these gravitational monsters, one question that has lingered is just how supermassive black holes gained mass so quickly.

May 4, 2024May 4, 2024 by Brian Koberlein

The Universe Could Be Filled With Ultralight Black Holes That Can't Die

This simulated image shows how black holes bend a starry background and capture light. Credit: NASA’s Goddard Space Flight Center

It’s that time again! Time for another model that will finally solve the mystery of dark matter. Or not, but it’s worth a shot. Until we directly detect dark matter particles, or until some model conclusively removes dark matter from our astrophysical toolkit the best we can do is continue looking for solutions. This new work takes a look at that old theoretical chestnut, primordial black holes, but it has a few interesting twists.

April 29, 2024April 29, 2024 by Brian Koberlein

A Cold Brown Dwarf is Belching Methane Into Space

This artist concept portrays the brown dwarf W1935. Credit: NASA, ESA, CSA, Leah Hustak (STScI)

Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperatures around 3,000 K and look essentially like stars.

April 13, 2024April 13, 2024 by Brian Koberlein

Neutron Stars Could be Heating Up From Dark Matter Annihilation

Artist’s impression of the magnetar in the star cluster Westerlund 1. Credit: ESO/L. Calçada

One of the big mysteries about dark matter particles is whether they interact with each other. We still don’t know the exact nature of what dark matter is. Some models argue that dark matter only interacts gravitationally, but many more posit that dark matter particles can collide with each other, clump together, and even decay into particles we can see. If that’s the case, then objects with particularly strong gravitational fields such as black holes, neutron stars, and white dwarfs might capture and concentrate dark matter. This could in turn affect how these objects appear. As a case in point, a recent study looks at the interplay between dark matter and neutron stars.