Researchers at the University of Illinois Urbana-Champaign have spotlighted another distant cosmic event that could threaten life on Earth: a kilonova, which results from the collision of two neutron stars. The findings appear in a recent issue of a leading astrophysics publication.
Based on their calculations, the collision of neutron stars about 36 light-years away from Earth could release intense radiation. This radiation might drive particle streams toward our planet, posing a potential, albeit unlikely, route to a mass extinction scenario.
Team leader Hale Perkins explained that neutron stars can form binary pairs, and when they merge, a rare and spectacular explosion unfolds.
Astronomers have shown that a kilonova produces narrow jets of gamma rays that shoot out from the merger in opposite directions. These jets can burn anything in their path for up to roughly 279 light-years. Yet, the chance that Earth sits directly in the jet’s path remains very small.
Surrounding the jets is intense gamma radiation. If a jet would pass within about 13 light-years of Earth, the gamma radiation could impact the planet as it travels through interstellar gas and dust, triggering the production of powerful X-rays. This X-ray emission tends to last longer than the gamma rays and has the potential to ionize Earth’s ozone layer.
The most dangerous effect involves high-energy charged particles, or cosmic rays. These particles travel outward in all directions, like a spreading bubble. If Earth were enveloped by such a cosmic ray sphere, the ozone layer could be stripped away, dramatically increasing surface UV exposure for thousands of years.
Scientists stress that this apocalyptic outcome would require an exceptionally close neutron-star merger by cosmic standards, making it a highly improbable event. In any case, researchers note that other natural hazards such as asteroids and solar flares present ongoing risks to humanity and living systems on the planet.
Earlier work by other scientists has helped solve lingering questions about mysterious radiation pulses from space, advancing our understanding of these extreme cosmic phenomena.