X-rays, spectra and neutron stars

or, in other words, here's my new story:

XMM-Newton line detection provides new tool to probe extreme gravity

A long-sought-after emission line of oxygen, carrying the imprint of strong gravitational fields, has been discovered in the XMM-Newton spectrum of an exotic binary system composed of two stellar remnants, a neutron star and a white dwarf. Astronomers can use this line to probe extreme gravity effects in the region close to the surface of a neutron star. More...

Image credits: ESA