Simulation Perfectly Matches What We See When Neutron Stars Collide

Numerical simulation of the resulting ejecta material of two merging neutron stars. Red colors refer to ejected material with a high fraction of neutrons which will appear typically redder than blue material that contains a higher fraction of protons. © I. Markin (University of Potsdam)
Numerical simulation of the resulting ejecta material of two merging neutron stars. Red colors refer to ejected material with a high fraction of neutrons which will appear typically redder than blue material that contains a higher fraction of protons. © I. Markin (University of Potsdam)

There are many mysteries in the world of astronomy and a fair number relate to the processes during the end of the life of a super massive star. Throw in the complexity of collisions and you have a real head scratching problem on your hands. In 2017 colliding neutron stars were detected and the data has allowed a new simulation to be tested with predictions beautifully matching observation.

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Spider Pulsars are Tearing Apart Stars in the Omega Cluster

Omega Centauri is the brightest globular cluster in the night sky. It holds about 10 million stars and is the most massive globular cluster in the Milky Way. It's possible that globulars and nuclear star clusters are related in some way as a galaxy evolves. Image Credit: ESO.
Omega Centauri is the brightest globular cluster in the night sky. It holds about 10 million stars and is the most massive globular cluster in the Milky Way. It's possible that globulars and nuclear star clusters are related in some way as a galaxy evolves. Image Credit: ESO.

Pulsars are extreme objects. They’re what’s left over when a massive star collapses on itself and explodes as a supernova. This creates a neutron star. Neutron stars spin, and some of them emit radiation. When they emit radiation from their poles that we can see, we call them pulsars.

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Gravitational Waves Reveal Surprising Secrets About Neutron Stars

The confirmation of gravitational waves back in 2017 continues to unlock whole new worlds of physics but also continues to elicit further questions.  The detection of each gravitational wave brings a new challenge – how to find out what caused the event.  Sometimes that is harder than it sounds.  Now a team led by Alejandro Vigna-Gomez of the University of Copenhagen thinks they found a model of star death that helps to explain some previously inexplicable findings – and points to a galaxy with many more massive neutron stars than previously thought.

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A Black Hole or Neutron Star Fell Into Another Star and Triggered a Supernova

Artist's conception of the ring of material surrounding a star shortly after engulfing a dense companion. Credit: Bill Saxton, NRAO/AUI/NSF

What happens when you slam a neutron star (or black hole, take your pick) into a companion star? A supernova, that’s what. And for the first time ever, astronomers think they’ve spotted one.

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Astronomers Think They’ve Found the Neutron Star Remnant Left Behind from Supernova 1987A

It was the brightest supernova in nearly 400 years when it lit the skies of the southern hemisphere in February 1987. Supernova 1987A – the explosion of a blue supergiant star in the nearby mini-galaxy known as the Large Magellanic Cloud – amazed the astronomical community. It offered them an unprecedented opportunity to observe an exploding star in real-time with modern instruments and telescopes. But something was missing. After the supernova faded, astronomers expected to find a neutron star (a hyper-dense, collapsed stellar core, made largely of neutrons) left-over at the heart of the explosion. They saw nothing.

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Astronomers Measure a 1-billion Tesla Magnetic Field on the Surface of a Neutron Star

Artist's impression of an Accreting X-Ray Pulsar drawing material from its companion star. - NASA

We recently observed the strongest magnetic field ever recorded in the Universe. The record-breaking field was discovered at the surface of a neutron star called GRO J1008-57 with a magnetic field strength of approximately 1 BILLION Tesla. For comparison, the Earth’s magnetic field clocks in at about 1/20,000 of a Tesla – tens of trillions of times weaker than you’d experience on this neutron star…and that is a good thing for your general health and wellbeing.

Neutron stars are the “dead cores” of once massive stars which have ended their lives as supernova. These stars exhausted their supply of hydrogen fuel in their core and a power balance between the internal energy of the star surging outward, and the star’s own massive gravity crushing inward, is cataclysmically unbalanced – gravity wins. The star collapses in on itself. The outer layers fall onto the core crushing it into the densest object we know of in the Universe – a neutron star. Even atoms are crushed. Negatively charged electrons are forced into the atomic nuclei meeting their positive proton counterparts creating more neutrons. When the core can be crushed no further, the outer remaining material of the star rebounds back into space in a massive explosion – a supernova. The resulting neutron star, made of the crushed stellar core, is so dense that a single sugar-cube-sized sampling would weigh billions of tons – as much as a mountain (though if you’re “worthy” you MIGHT able to lift it since Thor’s Hammer is made of the stuff). Neutron stars are typically about 20km in diameter and can still be a million degrees Kelvin at the surface.

But if they’re “dead,” how can neutron stars be some of the most magnetic and powerful objects in the Universe?

Composite image of the maelstrom at the heart of the Crab Nebula powered by a neutron star – Chandra X-Ray Observatory
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Astronomers Think They’ve Found the Neutron Star Remnant From Supernova 1987a

Artist's illustration of SN1987A. Credit: NRAO/AUI/NSF, B. Saxton

In 1987, astronomers witnessed a spectacular event when they spotted a titanic supernova 168,000 light-years away in the Hydra constellation. Designated 1987A (since it was the first supernova detected that year), the explosion was one of the brightest supernova seen from Earth in more than 400 years. The last time was Kepler’s Supernova, which was visible to Earth-bound observers back in 1604 (hence the designation SN 1604).

Since then, astronomers have tried in vain to find the company object they believed to be at the heart of the nebula that resulted from the explosion. Thanks to recent observations and a follow-up study by two international teams of astronomers, new evidence has been provided that support the theory that there is a neutron star at the heart of SN 1604 – which would make it the youngest neutron star known to date.

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Neutron stars of different masses can make a real mess when they collide

An artistic rendering of two neutron stars merging. Credit: NSF/LIGO/Sonoma State/A. Simonnet

When neutron stars collide, they go out with a tremendous bang, fueling an explosion up to a thousand times more powerful than a supernova. But sometimes they go out with a whimper, and a recent suite of simulations is showing why: they turn into a black hole.

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A brand new magnetar found, it’s only 240 years old

A massive flare ejected from a magnetar.

Magnetars are some of the most ridiculous objects in the universe. Composed of the densest material possible spinning faster than your kitchen blender, they generate the absolute most powerful magnetic fields the cosmos has ever seen – and astronomers have recently spotted a newborn.

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