Labeled Image of 47 Tucanae
New results from Chandra and other X-ray telescopes have provided one of the most reliable determinations yet of the relation between the radius of a neutron star and its mass. Neutron stars, the ultra-dense cores left behind after massive stars collapse, contain the densest matter known in the Universe outside of a black hole. This image contains data from a long Chandra observation of 47 Tucanae, a globular cluster where one of the eight neutron stars in the study is found. Lower-energy X-rays are red, those with intermediate energies are green, and the highest-energy X-rays are shown in blue.
(Credit: NASA/CXC/Michigan State/A.Steiner et al.;)

X-ray Image of NGC 6397
Neutron stars, the ultra-dense cores left behind after massive stars collapse, contain the densest matter known in the Universe outside of a black hole . New results from Chandra and other X-ray telescopes have provided one of the most reliable determinations yet of the relation between the radius of a neutron star and its mass. These results constrain how nuclear matter - protons and neutrons, and their constituent quarks, interact under the extreme conditions found in neutron stars.
(Credit: NASA/CXC/Michigan State/A.Steiner et al.;)