New X-Ray Tool to Help Study Outer Space

EXAFS, standing for Extended X-ray Absorption Fine Structures, are signatures in the spectra of X-ray astronomical sources that astrophysicists have been looking to identify for a very long time. Thus far, noticing and recording these signatures has been a very painstaking job, which has almost never ended in success. Now, with the help of a new tool, the Reflection Grating Spectrometer (RGS) aboard the XMM-Newton satellite, astronomers from Holland have managed to identify the elusive radiation for the first time and to conduct a series of scientific measurements on it.

Because the objects that supposedly emit this type of X-ray radiation never send out strong bursts, it has been very difficult for existing equipments to detect such faint signals. Now, astronomers C.P. de Vries and E. Costantini have succeeded in obtaining high-quality X-ray spectra of Scorpius X-1, one of the brightest X-ray sources in the known Universe, which is located roughly 2,800 parsecs (9,128 light-years or 89,600 trillion kilometers / 53,200 trillion miles) away from Earth.

What makes this achievement all the more exciting is the fact that the EXAFS signature comes from a region of space that is filled with dust, which means that visible light observatories cannot see through. In these cases, only radio and X-ray wavelengths, and sometimes infra-red, can manage to do that and hint at the objects that lie behind the “curtain.” But EXAFS actually offer scientists a very powerful instrument for studying grains that can be found in the interstellar medium (ISM), the matter that exists between the stars within a galaxy, or the gas, and dust that exists in the interstellar space.

Other techniques of studying stellar dust, including infra-red spectroscopy (IS), are limited, on account of the fact that they can only “see” dust with crystalline structures, while all other types remain hidden from view. A major advantage that EXAFS has over its infra-red counterpart is the fact that it can look at the matter in its line of sight and see its atomic composition, whereas IS can only distinguish the mineralogical composition of its targets.