neutron star Archives

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.

June 12, 2024June 12, 2024 by Evan Gough

Astronomers Find the Slowest-Spinning Neutron Star Ever

This artist's illustration shows CSIRO’s ASKAP radio telescope with two versions of the puzzling, newly-discovered celestial object: neutron star and white dwarf. Image Credit: Carl Knox, OzGrav

Most neutron stars spin rapidly, completing a rotation in seconds or even a fraction of a second. But astronomers have found one that takes its time, completing a rotation in 54 minutes. What compels this odd object to spin so slowly?

April 26, 2024April 26, 2024 by Mark Thompson

Astronomers Will Get Gravitational Wave Alerts Within 30 Seconds

Astronomers and astrophysicists could use these alerts and information to understand how neutron stars behave and study nuclear interactions between neutron stars and black holes colliding.

Any event in the cosmos generates gravitational waves, the bigger the event, the more disturbance. Events where black holes and neutron stars collide can send out waves detectable here on Earth. It is possible that there can be an event in visible light when neutron stars collide so to take advantage of every opportunity an early warning is essential. The teams at LIGO-Virgo-KAGRA observatories are working on an alert system that will alert astronomers within 30 seconds fo a gravity wave event. If warning is early enough it may be possible to identify the source and watch the after glow.

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.

April 9, 2024April 9, 2024 by Mark Thompson

A Neutron Star Merged with a Surprisingly Light Black Hole

Artwork of a neutron star–black hole merger. Credit: Carl Knox, OzGrav-Swinburne University.

Galactic collisions, meteor impacts and even stellar mergers are not uncommon events. neutron stars colliding with black holes however are a little more rare, in fact, until now, we have never observed one. The fourth LIGO-Virgo-KAGRA observing detected gravitational waves from a collision between a black hole and neutron star 650 million light years away. The black hole was tiny though with a mass between 2.5 to 4.5 times that of the Sun.

March 31, 2024March 31, 2024 by Mark Thompson

It Takes a Supercomputer to Properly Simulate a Neutron Star’s Surface

Neutron stars, the remains of massive stars that have imploded and gone supernova at the end of their life, can still create massive flares. These incredible bursts of energy release X-rays that propagate through space. It is a complex process to simulate but astronomers have turned to a supercomputer to help. Modelling the twisting magnetic fields, the interaction with gas and dust, the surface of flaring neutron stars has been revealed in incredible 3D.

March 29, 2024March 29, 2024 by Mark Thompson

Neutron Stars are Jetting Material Away at 40% the Speed of Light

It’s a well known fact that black holes absorb anything that falls into them. Often before material ‘vanishes’ inside it forms into an accretion disk around them. Like the progenitor stars, the black holes have powerful magnetic fields and these can generate jets that blast away from the black hole. A similar process occurs in neutron stars that are orbiting other stars and recent observations holes have shown that some material in the jets travel at speeds 35-40% the speed of light.

March 15, 2024March 15, 2024 by Carolyn Collins Petersen

The Maximum Mass of a Neutron Star is 2.25 Solar Masses

An outbursting, magnetically strong neutron star called a magnetar is seen here in an artist's illustration. Courtesy: NASA.

When stars grow old and die, their mass determines their ultimate fate. Many supermassive stars have futures as neutron stars. But, the question is, how massive can their neutron stars get? That’s one that Professor Fan Yizhong and his team at Purple Mountain Observatory in China set out to answer.

February 15, 2024February 15, 2024 by Brian Koberlein

Another Clue Into the True Nature of Fast Radio Bursts

Artist's concept of a magnetar. Credit: NASA/JPL-Caltech

Fast radio bursts (FRBs) are strange events. They can last only milliseconds, but during that time can outshine a galaxy. Some FRBs are repeaters, meaning that they can occur more than once from the same location, while others seem to occur just once. We still aren’t entirely sure what causes them, or even if the two types have the same cause. But thanks to a collaboration of observations from ground-based radio telescopes and space-based X-ray observatories, we are starting to figure FRBs out.