Astronomers have witnessed a completely new type of supernova explosion that they have called an “ultra-stripped supernova,” according to a new study from Caltech.

Supernova explosions occur when stars have finally relinquished the last of their nuclear fuel, which causes the cores of these stars to break down completely right before they begin expanding. While most of the material left in these stars is shuffled away from the onslaught of the supernova explosion, astronomers noted that when they studied the explosion known as “iPTF 14gqr,” just a tiny fraction of its matter ended up being ejected, according to Newsweek.

Mansi Kasliwal, one of the authors of the new study from Caltech, explained. “We saw this massive star’s core collapse, but we saw remarkably little mass ejected. We call this an ultra-stripped envelope supernova and it has long been predicted that they exist. This is the first time we have convincingly seen the core collapse of a massive star that is so devoid of matter.”

Astronomers have determined that the star they witnessed probably had a close companion which may have been a neutron star. Neutron stars are what are left over after large stars eject the majority of their layers following a supernova explosion, and it has been surmised that in the case of iPTF 14gqr this last supernova explosion may have happened so close to another neutron star that it ended up creating a binary neutron star system. While astronomers do know about such systems already, this would mark the first occasion that they have actually seen one being created.

Astronomers have witnessed a never-before-seen type of supernova https://t.co/NDq613lsgQ pic.twitter.com/HSCwbJz2XP — Newsweek (@Newsweek) October 12, 2018

iPTF 14gqr was observed for the first time in San Diego at the Palomar Observatory after astronomers performed a nightly study of the skies, searching for an event like a supernova. They were certainly in luck on the night in question after detecting this ultra-stripped supernova, which was determined to be one billion light-years away.

According to Caltech graduate student Kishalay De, after their observations astronomers sought the help of four other telescopes scattered around the world to confirm what they had witnessed. “As soon as the Sun rises you can’t take spectra anymore. We made sure we got a continuous sequence of spectra at these early times. We finally have evidence of the explosion that actually creates double neutron star systems.”

After studying Caltech’s work, Thomas Tauris, from the Aarhus Institute of Advanced Studies in Denmark, stated that he believes the astronomers were correct in determining that they had witnessed an ultra-stripped supernova.

“The authors succeeded with plenty of multi-wavelength observations shortly after the explosion, and the empirical evidence matches very nicely with theoretical expectations for such supernovae.”

The new study on the ultra-stripped supernova was published in Science.