Astronomers Discover A "One-In-10-Billion" Kilonova-In-Waiting For First Time

The observation of neutron stars merging, known as a kilonova, changed astronomy forever, but this is the first time we’ve spotted one before the explosion.

STEPHEN LUNTZ
Freelance Writer

Feb 2, 2023 5:48 AM



Artist's impression of a star system that will one day spread gold and other heavy elements across the galaxy.Image Credit: CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine/M. Zamani


A neutron star 11.400 light-years away is doomed to eventually collide with its giant companion. By the time it does, the giant will also be a neutron star, setting off an explosion that will seed the galaxy for thousands of light-years around with precious metals, known as a kilonova.

The makeup of the universe depends on extremely rare events. Supernovas, which occur roughly once a century in galaxies as large as the Milky Way create and disperse metals that go on to form the basis of future planets. Some of the rarer metals require something even more exotic, the collision of two neutron stars, first observed in 2017 when gravitational waves alerted us to one of the most important events in astronomical history.

Neutron stars are the result of supernovas of stars with masses 10-25 times the mass of the Sun. Although thousands of them exist in the Milky Way, two seldom orbit each other so the discovery of a future such pair by the SMARTS 1.5-meter Telescope in Chile, announced in Nature, is a stunning achievement. Even some neutron stars in mutual orbits will never form a kilonova if the distance between them is too great. Consequently, the discovery that the system known as CPD-29 2176 is tight enough to eventually collapse turns a big discovery into something truly epic.

NASA’s Neil Gehrels Swift Observatory first raised the possibility there was something interesting about CPD-29 2176 when it observed a magnetar-like burst in 2019. Follow-up observations using SMARTS revealed a neutron star orbiting a massive main-sequence star.

More:
https://www.iflscience.com/astronomers-discover-a-one-in-10-billion-kilonova-in-waiting-for-first-time-67360