Astronomers discover for the first time a special variety of neutron star outside of the Milky Way galaxy using ground-based and space telescopes.

What Are Neutron Stars?

Neutron stars are the collapsed, burnt-out cores of dead stars. When large stars reach the end of their lives and explode in a violent supernova, their outer layers are blown off, leaving behind a neutron star.

A neutron star typically has a mass that is half a million times the mass of planet Earth despite measuring just about the size of London. These exotic objects are also usually extremely hot, highly radioactive, and have intense magnetic fields.

Rare Neutron Star

The newly discovered neutron star belongs to a rare variety that has low magnetic field and no stellar companion. It was found within the remains of the supernova called E0102 in the Small Magellanic Cloud about 200,000 light-years away.

Oxygen-rich supernova remnants such as the E0102 offers scientists an opportunity to better understand how massive star fuse lighter elements into heavier ones before they explode.

Astronomers made the discovery using the Multi Unit Spectroscopic Explorer instrument on ESO's Very Large Telescope in Chile, and NASA's Chandra X-ray Observatory.

The lack of extended radio emission or pulsed X-ray radiation suggests that the object is an isolated neutron star with a low magnetic field.

"The energy distribution of the source indicates that this object is an isolated neutron star: a Central Compact Object akin to those present in the Cas A and Puppis A supernova remnants, and the first of its kind to be identified outside of our Galaxy," researchers led by Frédéric Vogt, an ESO fellow, reported in their study.

First One To Be Spotted Beyond Milky Way Galaxy

New data revealed that E0102 has a ring of gas centered on an X-ray source. Data from Chandra and VLT's MUSE instrument suggest that this particular source is an isolated neutron star, which was created in a supernova explosion that occurred about 2,000 years ago.

A total of 10 other similar objects have been found in the Milky Way, but this is the first one that was spotted outside of the galaxy.

"This is the first object of its kind to be confirmed beyond the Milky Way, made possible using MUSE as a guidance tool. We think that this could open up new channels of discovery and study for these elusive stellar remains," said study researcher Liz Bartlett, an ESO fellow.

The findings were published in the journal Nature Astronomy.