New measurements about neutron stars size, revealed a radius between 10,4 and 11,9 km

696.340 km.. This is the medium radius of The Sun, our host star! Ok, work with your imagination and shrink it to only 11km but... with the same mass! Yes, a star with a radius of 11 km. This is what happen when a star, at the end of his cycle, becomes a neutron star 

What is a neutron star?

A neutron star is a debauched matter compact star, as the result of the end of nuclear fusion of a massive star, over 10-times more massive than the Sun. There are 2 ways in which a massive star could end, after its explosion, depending of the remaining mass: if the mass is over 3 Sun masses the explosion will generate a black hole, if it is less than 3it will be a neutron star. This kind of object has this peculiarity: 3 solar masses in a few-tens km radius!

It means that if you could take a coffee spoon of this star, it would weight billions of tons! 

The study

This incredibly precise measurements has been possible studying an event called Gw 170817, in which two neutron stars melted themselves. This event happened 120 millions of years ago (when dinosaurs still lived on Earth.... and Queen Elizabeth for sure XD) and has allowed to take enthusiast results about the size of neutron star. Astrophysics of Max Planck Institute compared all the known equations about neutron stars, derived by nuclear physics, with the data revealed by the observations of this event. This comparison of this two groups of data allowed to determinate the radius of a neutron star with extremely precision, as it never been done before. 

As told by Stephanie Brown and Collin Capano, two of the first author of this study:

"results obtained are exciting not only because we were able to greatly improve the measurements of neutron star rays, but because they show us the fate of neutron stars during binary fusion"

Infact, in the future, it will be possible establish the nature of similar event:  black holes meltdown or neutron stars meltdown?