Neutron Stars Archives

October 23, 2024October 25, 2024 by Matt Williams

Neutron Stars May be Shrouded in Extremely Light Particles Called Axions

Image from a computer simulation of the distribution of matter in the universe. Orange regions host galaxies; blue structures are gas and dark matter. Credit: TNG Collaboration

Since the 1960s, astronomers have theorized that the Universe may be filled with a mysterious mass that only interacts with “normal matter” via gravity. This mass, nicknamed Dark Matter (DM), is essential to resolving issues between astronomical observations and General Relativity. In recent years, scientists have considered that DM may be composed of axions, a class of hypothetical elementary particles with low mass within a specific range. First proposed in the 1970s to resolve problems in the Standard Model of particle physics, these particles have emerged as a leading candidate for DM.

In addition to growing evidence that this could be the case, researchers at CERN are developing a new telescope that could help the scientific community look for axions – the CERN Axion Solar Telescope (CAST). According to new research conducted by an international team of physicists, these hypothetical particles may occur in large clouds around neutron stars. These axions could be the long-awaited explanation for Dark Matter that cosmologists have spent decades searching for. What’s more, their research indicates that these axions may not be very difficult to observe from Earth.

August 7, 2024August 7, 2024 by Mark Thompson

How a Black Hole Could Eat a Neutron Star from the Inside Out

Illustration of a neutron star. Credit: ESA

Primordial black holes are thought to have formed early in the evolution of the universe. None have been discovered yet but if they do exist and they may be plentiful, drifting almost invisibly through the cosmos, then they might account for dark matter. One possible way to search for them is to see the results of their meals and a bizarre new theory suggests low mass black holes could be captured by neutron stars and become trapped inside, devouring them from within. If these strange objects existed then it would make neutron stars less common in locations where black holes would proliferate as observed around Galactic centre.

June 30, 2024June 30, 2024 by Laurence Tognetti

Neutron Stars: Why study them? What makes them so fascinating?

Artist’s rendition of a neutron star. (Credit: ESO / L. Calçada)

Over the last several months, Universe Today has explored a plethora of scientific disciplines, including impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics, cosmochemistry, meteorites, radio astronomy, extremophiles, organic chemistry, black holes, cryovolcanism, planetary protection, dark matter, and supernovae, and how each of these unique disciplines continue to teach is about the cosmos and our place throughout its vastness.

Here, Universe Today discusses the field of neutron stars with Dr. Stuart Shapiro, who is a Professor of Physics and Astronomy and NCSA Senior Research Scientist at the University of Illinois at Urbana-Champaign, regarding the importance of studying neutron stars, the benefits and challenges, the most intriguing aspect about neutron stars he’s studied throughout his career, and any advice he can offer upcoming students who wish to pursue studying neutron stars. Therefore, what is the importance of studying neutron stars?

June 28, 2024June 28, 2024 by Matt Williams

These Three Neutron Stars Shouldn't Be So Cold

Artist's impression of a neutron star, with white/blue filaments are streaming out from its polar regions, representing magnetic field lines. Credit: ESA

Neutron stars are among the densest objects in the Universe, second only to black holes. Like black holes, neutron stars are what remains after a star reaches the end of its life cycle and undergoes gravitational collapse. This produces a massive explosion (a supernova), in which a star sheds its outer layers and leaves behind a super-compressed stellar remnant. In fact, scientists speculate that matter at the center of the star is compressed to the point that even atoms collapse and electrons merge with protons to create neutrons.

Traditionally, scientists have relied on the “Equation of State” – a theoretical model that describes the state of matter under a given set of physical conditions – to understand what physical processes can occur inside a neutron star. But when a team led by scientists from the Spanish National Research Council (CSIC) examined three exceptionally young neutron stars, they noticed they were 10-100 times colder than other neutron stars of the same age. For this, the researchers concluded that these three stars are inconsistent with most of the proposed equations of state.

June 24, 2024June 24, 2024 by Matt Williams

Simulating the Last Moments Before Neutron Stars Merge

Volume rendering of density in a simulation of a binary neutron star merger. New research shows that neutrinos created in the hot interface between the merging stars can be briefly trapped and remain out of equilibrium with the cold cores of the merging stars for 2 to 3 milliseconds. Credit: David Radice/Penn State

When stars reach the end of their life cycle, they shed their outer layers in a supernova. What is left behind is a neutron star, a stellar remnant that is incredibly dense despite being relatively small and cold. When this happens in binary systems, the resulting neutron stars will eventually spiral inward and collide. When they finally merge, the process triggers the release of gravitational waves and can lead to the formation of a black hole. But what happens as the neutron stars begin merging, right down to the quantum level, is something scientists are eager to learn more about.

When the stars begin to merge, very high temperatures are generated, creating “hot neutrinos” that remain out of equilibrium with the cold cores of the merging stars. Ordinarily, these tiny, massless particles only interact with normal matter via weak nuclear forces and possibly gravity. However, according to new simulations led by Penn State University (PSU) physicists, these neutrinos can weakly interact with normal matter during this time. These findings could lead to new insights into these powerful events.

January 19, 2024January 19, 2024 by Evan Gough

Is this the Lightest Black Hole or Heaviest Neutron Star?

An international team of astronomers have found a new and unknown object in the Milky Way that is heavier than the heaviest neutron stars known and yet simultaneously lighter than the lightest black holes known. Image Credit: University of Manchester/Max Planck Institutue for Radio Astronomy

About 40,000 light-years away, a rapidly spinning object has a companion that’s confounding astronomers. It’s heavier than the heaviest neutron stars, yet at the same time, it’s lighter than the lightest black holes. Measurements place it in the so-called black hole mass gap, an observed gap in the stellar population between two to five solar masses. There appear to be no neutron stars larger than two solar masses and no black holes smaller than five solar masses.

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.

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.

February 15, 2023February 15, 2023 by Laurence Tognetti

Magnetars are Extreme in Every Way, Even Their Volcanoes

Artist rendition of a magnetar eruption. These could be source of fast radio bursts. (Credit: NASA Goddard Space Flight Center)

In a recent study published in Nature Astronomy, an international team of researchers led by NASA and The George Washington University examined data from an October 2020 detection of what’s known as a “large spin-down glitch event”, also known as an “anti-glitch”, from a type of neutron star known as a magnetar called SGR 1935+2154 and located approximately 30,000 light-years from Earth, with SGR standing for soft gamma repeaters. Such events occur when the magnetar experiences a sudden decrease in its rotation rate, which in this case was followed by three types of radio bursts known as extragalactic fast radio bursts (FRBs) and then pulsed radio emissions for one month straight after the initial rotation rate decrease.

February 2, 2023February 2, 2023 by Evan Gough

This Binary System is Destined to Become a Kilonova

This is an artist’s impression of the first confirmed detection of a star system that will one day form a kilonova — the ultra-powerful, gold-producing explosion created by merging neutron stars. Image Credit: CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani

Kilonovae are extraordinarily rare. Astronomers think there are only about 10 of them in the Milky Way. But they’re extraordinarily powerful and produce heavy elements like uranium, thorium, and gold.

Usually, astronomers spot them after they’ve merged and emitted powerful gamma-ray bursts (GRBs.) But astronomers using the SMARTS telescope say they’ve spotted a kilonova progenitor for the first time.