The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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Neutron stars are the compressed cores of giant stars, left behind after the star exploded in a supernova. They are so dense that a sugar cube’s amount of neutron star material would weigh as much as all the people on Earth!
Scientists aren’t sure what happens to matter when it gets squeezed this hard. We can’t look directly inside a neutron star. Instead, scientists determine their properties by observing them from afar, and compare these to different models of what happens inside. All neutron stars must obey the same laws of physics, so only one model can be correct. Thus, the hunt is on for the one neutron star ‘equation of state’ that rules them all.
Three young neutron stars observed by ESA’s XMM-Newton and NASA’s Chandra space telescopes are much colder than most models predict. A detailed analysis by a research team at the Institute of Space Sciences (ICE-CSIC) and Institute of Space Studies of Catalonia (IEEC) concludes that the three cool oddballs must have cooled by sending out trillions and trillions of tiny particles called neutrinos. This fast-cooling mechanism is called the direct Urca process; only around a quarter of established neutron star equation of state models incorporate this mechanism. In other words, the other three quarters of models are ruled out.