RX J1856.5 3754 Neutron star

 Neutron stars are among the most extreme objects in the Universe. They form during the explosion of a supernova, the last phase of life of a very massive star. During this process, the star’s core collapses under its own gravity, while the outer surface layers are thrown into space. The collapsed nucleus, of very high density, can form either a neutron star or a black hole depending on the initial mass of the star.

Among the neutron stars one of the closest ever observed to our planet is RX J1856.5 3754, just 400 light years from Earth, here taken in x-rays from Chandra.

At the time of its discovery in 1992, the neutron star disoriented astronomers, as it did not appear to be associated with any supernova remnants. Only subsequent joint observations between Hubble and Chandra have shed light on this mystery. The star should have formed about a million years ago and as a result the gases of the associated nebula will have diluted in space until they become invisible. Furthermore, the neutron star is moving in space at a speed of 110 km/s, making it very difficult to determine its initial position.

The same studies then showed that RX J1856.5 3754 has a diameter of about 14 km and a surface temperature of 400 thousand degrees Celsius.

Credit:  Credit: NASA/SAO/CXC/J.Drake et al.