Brian Koberlein, Author at Universe Today

May 1, 2023May 1, 2023 by Brian Koberlein

Aliens Could Map Earth From its Mobile Phone Towers

A mobile cell tower on a clear day. Credit: Ervins Strauhmanis, via Flickr

Mobile phones are so ubiquitous that we typically don’t think about how they work. They just do, much to our benefit, and sometimes annoyance. But the key to their function is a vast array of radio transmission towers. These cell towers span a large percentage of Earth’s land surface, particularly in heavily populated areas, and they transmit microwave signals all the time. With all those cell towers emitting all those radio signals, a fun question to ask is whether those signals could be detected by an alien civilization.

April 30, 2023April 30, 2023 by Brian Koberlein

Bizarre Exoplanet Breaks All the Orbital Rules

Artist's view of WASP-39b, a hot gas planet similar to WASP-131b. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

In our solar system, the planetary orbits all have a similar orientation. Their orbital planes vary by a few degrees, but roughly the planets all orbit in the same direction. This invariable plane as it’s known also has an orientation within a few degrees of the Sun’s rotational plane. Most planetary systems have a similar arrangement, where planetary orbits and stellar rotation are roughly aligned, but a few exoplanets defy this trend, and we aren’t entirely sure why.

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.

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. Some stars emit superflares similar to this, but many times brighter and stronger than those from the Sun. 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.