The gold that comprises the ring in your ring, the jewellery, and the uranium used as fuel in nuclear power plants is believed to return from the violent conditions created when two ultradense dead stars called neutron stars collide.
This collision between neutron stars also generates ripples in spacetime called gravitational waves, blasts of high-energy radiation called gamma-ray bursts, and a flash of sunshine called a kilonova that could be detected here on Earth. Signatures from just such an event were detected on 17 August 2017.
Now, a team of scientists, including researchers from the Max Planck Institute for Gravitational Physics and the University of Potsdam, have used a complicated software tool to research the signatures of this kilonova explosion, adding in data from radio and X-ray observations of other neutron stars, nuclear physics calculations and findings from collision experiments conducted in particle accelerators here on Earth.
The hassle could help higher understand the exotic and turbulent environments generated when ultra-dense dead stars smash together to create the one sites scientists know of that may forge elements heavier than iron.
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“Our latest method will help to research the properties of matter at extreme densities. It can also allow us to raised understand the expansion of the universe and to what extent heavy elements are formed during neutron star mergers,” team member and Max Planck Institute for Gravitational Physics scientist Tim Dietrich said in an announcement.
Neutron star smash-ups as extreme cosmic laboratories
Neutron stars are born when massive stars reach the tip of their fuel for nuclear fusion at their cores. This causes that core to collapse rapidly while the outer layers of the star are slewed away, abandoning a body with a mass of between one and two times that of the sun squashed right into a width akin to a city here on Earth, about 12 miles (20 kilometers).
Because of this, the fabric that comprises a neutron star is so dense that a mere sugar cube-sized lump of it, when delivered to Earth, would weigh as much as 3,000 Empire State Buildings or the whole human race. This dead star matter can be extraordinary since it is wealthy in neutrons, particles normally locked up in atomic nuclei with protons.
When neutron stars collide, sprays of this neutron-rich matter are launched into space. This creates an environment full of free neutrons that could be quickly snapped up by other atoms, creating very heavy elements beyond the bounds of the periodic table—something scientists called the “rapid capture process” or “r-process.”
These elements are unstable and decay into stable heavy elements like gold and uranium. This decay is accompanied by the emission of electromagnetic radiation—the sunshine that forms the kilonova flash.
Which means studying the kilonova occurring after a neutron star merger is the unique path to studying the physical processes that forge elements beyond iron, which may’t be created within the fiery hearts of even essentially the most massive stars.
Up to now, just one merger of neutron stars in a contracting binary system has been recorded in its gravitational waves and electromagnetic emissions.
The event, designated GW170817, emerged from colliding neutron stars positioned 130 million light-years from Earth, which swirled together and merged, creating signals spotted here on Earth in 2017.
The team used their software to create a model of this event comprised of gravitational waves from the previous few spirals of those neutron stars around one another before they collided, the gamma-ray burst launched because the collision occurred, and the kilonova emission emitted by the environment across the merger between days and years after it occurred.
“By analyzing the information coherently and concurrently, we get more precise results,” team member and Utrecht University scientist Peter T. H. Pang said.
This allowed the team to exactly detail what happened during this neutron star merger that occurred over 130 million years ago and would have enriched its surroundings with gold, uranium, and other heavy elements.
The model that was developed by the team needs to be suitable to be used in detailing the events that transpire when other neutron stars collide.
This investigation might be bolstered because the U.S-based Laser Interferometer Gravitational-Wave Observatory (LIGO), the Italy-based Virgo, and Japan-based Kamioka Gravitational Wave Detector (KAGRA) gravitational wave detectors receive upgrades ahead of future observing runs that may “hear” much more ripples in spacetime launched by neutron star collisions.