Brian Koberlein, Author at Universe Today

April 29, 2023April 29, 2023 by Brian Koberlein

These Stars are Already Merging, but Their Future Will Be Catastrophic

Artist's view of the contact binary that will eventually merge as black holes. Credit: UCL / J. daSilva

Close-orbiting binaries are a ticking time bomb. Over time they spiral ever closer to each other until they merge in a cataclysmic explosion such as a supernova. But in the middle of their story, things can get interesting. Some stars collapse into a white dwarf before merging with their partner, others edge so close to each other that their surfaces touch for a time, becoming contact binaries before finally colliding. But one newly discovered binary system will have a wild ride before its final demise.

April 28, 2023April 28, 2023 by Brian Koberlein

You Don't Want to Be Within 160 Light-Years of a Supernova

A nearby supernova desolates a nearby habitable planet. Credit: NASA/CXC/M. Weiss

Supernovae are incredibly common in the universe. Based on observations of isotopes such as aluminum-26, we know that a supernova occurs on average about every fifty years in the Milky Way alone. A supernova can outshine a galaxy, so you wouldn’t want your habitable planet to be a few light years away when it goes off. Fortunately, most supernovae have occurred very far away from Earth, so we haven’t had to concern ourselves with wearing sunscreen at night. But it does raise an interesting question. When it comes to supernovae, how close is too close? As a recent study shows, the answer depends on the type of supernova.

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April 27, 2023April 27, 2023 by Brian Koberlein

What a Mess. A Black Hole's Stellar Meal is Brighter and Longer Lasting Than Ever Seen Before

Illustration of a star being ripped apart by a black hole. Credit: NASA/CXC/U. Michigan/J. Miller et al.; Illustration: NASA/CXC/M. Weiss

It’s a tale as old as time. A cataclysmic event occurs in the universe and releases a tremendous amount of energy in a short period of time. The event then fades into the darkness and the cosmos returns to normal. These short-lived cosmic events are known as transients and include things such as supernovae and gamma-ray bursts. Transients are quite common, but some of them can challenge explanations. Take for example the transient known as ZTF20abrbeie, nicknamed Scary Barbie.

April 27, 2023April 27, 2023 by Brian Koberlein

Gravitational Waves From Pulsars Could Be Used to Probe the Interior of the Sun

A solar flare, as it appears in extreme ultra-violet light. Credit: NASA/SFC/SDO

Gravitational wave astronomy is still in its early stages. So far it has focused on the most energetic and distinct sources of gravitational waves, such as the cataclysmic mergers of black holes and neutron stars. But that will change as our gravitational telescopes improve, and it will allow astronomers to explore the universe in ways previously impossible.

April 26, 2023April 26, 2023 by Brian Koberlein

Is This a Black Hole or a New Type of Star?

A boson star as it would appear to the EHT. Credit: Olivares et al

Within general relativity, black holes are easy to define. They are objects with an event horizon. This horizon is like a line in the sand, where anything crossing it is forever trapped within the black hole. Quantum theory might allow for energy to escape through Hawking radiation, but classical black holes are a one-way trip.

February 26, 2023February 26, 2023 by Brian Koberlein

Even the Largest Structures in the Universe Have a Magnetic Field

A composite image showing the magnetic fields of the cosmic web. Credit: Vernstrom et al

The universe is filled with magnetic fields. Although the universe is electrically neutral, atoms can be ionized into positively charged nuclei and negatively charged electrons. When those charges are accelerated, they create magnetic fields. One of the most common sources of magnetic fields on large scales comes from the collisions between and within interstellar plasma. This is one of the major sources of magnetic fields for galactic-scale magnetic fields.

February 17, 2023February 17, 2023 by Brian Koberlein

When Neutron Stars Collide, the Explosion is Perfectly Spherical

This artist’s impression shows two tiny but very dense neutron stars at the point at which they merge and explode as a kilonova. Such a very rare event is expected to produce both gravitational waves and a short gamma-ray burst, both of which were observed on 17 August 2017 by LIGO–Virgo and Fermi/INTEGRAL respectively. Subsequent detailed observations with many ESO telescopes confirmed that this object, seen in the galaxy NGC 4993 about 130 million light-years from the Earth, is indeed a kilonova. Such objects are the main source of very heavy chemical elements, such as gold and platinum, in the Universe.

Kilonovae are incredibly powerful explosions. Whereas regular supernovae occur when two white dwarfs collide, or the core of a massive star collapses into a neutron star, kilonovae occur when two neutron stars collide. You would think that neutron star collisions would produce explosions with all sorts of strange shapes depending on the angle and speed of the collisions, but new research shows kilonovae are very spherical, and this has some serious implications for cosmology.

December 29, 2022December 29, 2022 by Brian Koberlein

New Measurements of Galaxy Rotation Lean Towards Modified Gravity as an Explanation for Dark Matter

Although dark matter is a central part of the standard cosmological model, it’s not without its issues. There continue to be nagging mysteries about the stuff, not the least of which is the fact that scientists have found no direct particle evidence of it. Despite numerous searches, we have yet to detect dark matter particles. So some astronomers favor an alternative, such as Modified Newtonian Dynamics (MoND) or modified gravity model. And a new study of galactic rotation seems to support them.

December 15, 2022December 15, 2022 by Brian Koberlein

Rubble Pile Asteroids Might be the Best Places to Build Space Habitats

Illustration: SpaceX Crew Dragon at ISS — An illustration shows SpaceX's Crew Dragon capsule approaching the International Space Station. (Credit: SpaceX)

The stars call to us, as Carl Sagan once said. Given the human drive to explore our world and expand our reach, it is likely only a matter of time before we begin to build our homes in the solar system. The Moon and Mars could be acceptable destinations, but nearby asteroids could also become homes, as a recent study shows.

December 14, 2022December 14, 2022 by Brian Koberlein

The Formation of the Southern Ring Nebula was Messier Than the Death of a Single Star

JWST images of the Southern Ring Nebula as seen from the telescope's NIRCam (left) and MIRI (right). Credit: NASA, ESA, CSA, and STScI

Two thousand five hundred years ago, during the height of the bronze age, an old red star died. Its outer layers expanded over time, becoming what is now known as the Southern Ring Nebula, or less romantically, NGC 3132. By the looks of it, this planetary nebula looks like many others. As Sun-like stars die, they swell to become red giants before becoming a white dwarf, and their outer layers typically become a planetary nebula. But a recent study finds that this particular nebula formed in a way quite messier than we had thought.