XMM will reveal finer X-ray spectral details

For a fine analysis of the energy of X-rays from an individual cosmic source, XMM's Reflection Grating Spectrometer (RGS) will draw off about half the X-rays from two of the three telescopes. Showing 20 times more detail than did ESA's Exosat X-ray mission in the 1980s, RGS will make emission from particular chemical elements much easier to recognise. In this example, when XMM examines the segment with a black background in the Exosat spectrum, iron (Fe) and oxygen (O) emissions that merged there will be clearly separated. The source is the star Capella and the XMM/RGS spectrum is simulated. [Image Date: 1997-10-00] [97.11.015-004]