Neutron Stars Archives

January 21, 2021January 21, 2021 by Brian Koberlein

Strange Green Star is the Result of a Merger Between two White Dwarfs

Artist view of a binary white dwarf. Credit: University of Sheffield

A white dwarf isn’t your typical kind of star. While main sequence stars such as our Sun fuse nuclear material in their cores to keep themselves from collapsing under their own weight, white dwarfs use an effect known as quantum degeneracy. The quantum nature of electrons means that no two electrons can have the same quantum state. When you try to squeeze electrons into the same state, they exert a degeneracy pressure that keeps the white dwarf from collapsing.

December 22, 2020December 22, 2020 by Brian Koberlein

If Axions Explain Dark Matter, it Could be Possible to Detect Them Nearby Neutron Stars

The Robert C. Byrd Green Bank Telescope. Credit: Green Bank Observatory/NRAO

As we continue to search for dark matter particles, one thing is very clear: they cannot be any of the elementary particles we’ve discovered so far. The particles would need to have mass, but interact with light only weakly. Of the known particles, neutrinos fit that description, but neutrinos have a tiny mass, and aren’t nearly enough to explain dark matter. Some other kind of particle must make up the majority of dark matter.

November 17, 2020November 17, 2020 by Evan Gough

Merging Black Holes and Neutron Stars. All the Gravitational Wave Events Seen So Far in One Picture

The mergers of compact objects discovered so far by LIGO and Virgo (in O1, O2 and O3a). The diagram shows black holes (blue), neutron stars (orange) and compact objects of unknown nature (grey), which were detected by their gravitational-wave emission. Each merger of a binary system corresponds to three compact objects shown: the two merging objects and the result of the merger. A selection of black holes (violet) and neutron stars (yellow) discovered by electromagnetic observations is shown for comparison. Image Credit: LIGO Virgo Collaboration / Frank Elavsky, Aaron Geller / Northwestern

The Theory of Relativity predicted the existence of black holes and neutron stars. Einstein gets the credit for the theory because of his paper published in 1915, even though other scientists’ work helped it along. But regardless of the minds behind it, the theory predicted black holes, neutron stars, and the gravitational waves from their mergers.

It took about one hundred years, but scientists finally observed these mergers and their gravitational waves in 2015. Since then, the LIGO/Virgo collaboration has detected many of them. The collaboration has released a new catalogue of discoveries, along with a new infographic. The new infographic displays the black holes, neutron stars, mergers, and the other uncertain compact objects behind some of them.

November 13, 2020November 13, 2020 by Brian Koberlein

Do neutron star collisions produce black holes?

neutron star merger and gamma ray burst — Artistic representation of two merging neutron stars. Credit: Dana Berry, SkyWorks Digital, Inc.

In principle, creating a stellar-mass black hole is easy. Simply wait for a large star to reach the end of its life, and watch its core collapse under its own weight. If the core has more mass than 2 – 3 Suns, then it will become a black hole. Smaller than about 2.2 solar masses and it will become a neutron star. Smaller than 1.4 solar masses and it becomes a white dwarf.

October 29, 2020October 29, 2020 by Evan Gough

New Simulation Shows Exactly What’s Happening as Neutron Stars Merge

gamma-ray burst from neutron star merger — Artist rendering of colliding neutron stars. Credit: Robin Dienel/Carnegie Institution for Science

Neutron stars are the remnants of massive stars that explode as supernovae at the end of their fusion lives. They’re super-dense cores where all of the protons and electrons are crushed into neutrons by the overpowering gravity of the dead star. They’re the smallest and densest stellar objects, except for black holes, and possibly other arcane, hypothetical objects like quark stars.

When two neutron stars merge, we can detect the resulting gravitational waves. But some aspects of these mergers are poorly-understood. One question surrounds short-lived gamma-ray bursts from these mergers. Previous studies have shown that these bursts may come from the decay of heavy elements produced in a neutron star merger.

A new study strengthens our understanding of these complex mergers and introduces a model that explains the gamma rays.

September 10, 2020September 10, 2020 by Brian Koberlein

Could There Be a Form of Life Inside Stars?

This dramatic infrared image shows the nearby star formation region Monoceros R2, located some 2700 light-years away in the constellation of Monoceros (the Unicorn). The picture was created from exposures in the near infrared bands Y, J and Ks taken by the VISTA survey telescope at ESO’s Paranal Observatory. Monoceros R2 is an association of massive hot young stars illuminating a beautiful collection of reflection nebulae, embedded in a large molecular cloud. This image is available as a mounted image in the ESOshop.

Are we alone in the universe?

It is one of the most profound questions posed in modern astronomy. But although our understanding of the cosmos has grown significantly, the question remains unanswered. We know that Earth-like planets are common, as are the building blocks necessary for terrestrial life, and yet we still haven’t found definitive evidence for life beyond Earth. Perhaps part of our problem is that we are mostly looking for life similar to our own. It is possible that alien life is so radically different from that of Earth it goes unnoticed.

June 17, 2020June 17, 2020 by Evan Gough

Why Pulsars Are So Bright

Pulsars are fast-spinning neutron stars that emit narrow, sweeping beams of radio waves. A new study identifies the origin of those radio waves. NASA’s Goddard Space Flight Center

When pulsars were first discovered in 1967, their rhythmic radio-wave pulsations were a mystery. Some thought their radio beams must be of extraterrestrial origin.

We’ve learned a lot since then. We know that pulsars are magnetized, rotating neutrons stars. We know that they rotate very rapidly, with their magnetic poles sending sweeping beams of radio waves out into space. And if they’re aimed the right way, we can “see” them as pulses of radio waves, even though the radio waves are steady. They’re kind of like lighthouses.

But the exact mechanism that creates all of that electromagnetic radiation has remained a mystery.

May 7, 2020May 7, 2020 by Brian Koberlein

A Fast Radio Burst Has Been Detected From Inside The Milky Way

An illustration fast radio bursts in the night sky. Credit: James Josephides/Mike Dalley

Now and then there are bright flashes of radio light in the sky, and they are bothering astronomers. They are called Fast Radio Bursts (FRBs), and they’re like the chirp of a smoke alarm that needs its battery changed. They last for such a short time that it’s difficult to track down the source. They have become a nagging mystery in astronomy.

March 11, 2020March 11, 2020 by Nancy Atkinson

Neutron Star Measures Just 22 Kilometers Across

A typical neutron star with a radius of eleven kilometres is about as large as a medium-sized city. Credit: NASA's Goddard Space Flight Center

How big is a neutron star? These extreme, ultra-dense collapsed stars are fairly small, as far as stellar objects are concerned. Even though they pack the mass of a full-sized star, their size is often compared to the width of a medium-to-large-sized city. For years, astronomers have pegged neutron stars at somewhere between 19-27 km (12 to 17 miles) across. This is quite actually quite precise, given the distances and characteristics of neutrons stars. But astronomers have been working to narrow that down to an even more precise measurement.

An international team of researchers has now done just that. Using data from several different telescopes and observatories, members of the Max Planck Institute for Gravitational Physics, theAlbert Einstein Institute (AEI) have narrowed the size estimates for neutron stars by a factor of two.

January 30, 2020January 30, 2020 by Brian Koberlein

Astronomers See Space Twist Around A White Dwarf 12,000 Light Years Away

A white dwarf and pulsar orbit each other as Parkes observatory watches. Credit: Mark Myers/ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav)

The theory of general relativity is packed with strange predictions about how space and time are affected by massive bodies. Everything from gravitational waves to the lensing of light by dark matter. But one of the oddest predictions is an effect known as frame-dragging. The effect is so subtle it was first measured just a decade ago. Now astronomers have measured the effect around a white dwarf, and it tells us how some supernovae occur.