Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A new X-ray spectroscopic tool for probing the interstellar medium

02.04.2009
Based on the article: “Physical properties of amorphous solid interstellar material from X-ray absorption spectroscopy of Scorpius X-1”, by C.P. de Vries and E. Costantini

Astronomy & Astrophysics is publishing the first clear detection of signatures long sought in the spectra of X-ray astronomical sources, the so-called EXAFS signatures, standing for “Extended X-ray Absorption Fine Structure”.

EXAFS is a powerful tool for studying the structure of grains in the interstellar medium (ISM). It gives a more detailed picture of the composition and structure of amorphous grains in the ISM.

Astronomy & Astrophysics is publishing the first clear detection of signatures long sought in the spectra of X-ray astronomical sources. These signatures, the so-called EXAFS standing for “Extended X-ray Absorption Fine Structure”, were observed with an X-ray spectroscopic technique that is common in materials sciences.

Up to now, EXAFS studies of astronomical sources have been unsuccessful because of the weak X-ray signals received from celestial objects. Using the Reflection Grating Spectrometer (RGS) onboard the XMM-Newton satellite, Dutch astronomers C.P. de Vries and E. Costantini have obtained high-quality X-ray spectra of Scorpius X-1, one of the brightest X-ray sources in the sky, located about 2800 parsecs from the Earth. For the first time, they have found clear evidence of an EXAFS signature coming from the dust seen toward a celestial source.

EXAFS is a powerful tool for studying the structure of grains in the interstellar medium (ISM). It is based on the phenomenon that X-ray photons can eject electrons from atoms inside solid particles, which in turn can be backscattered onto the emitting atom by atoms in their immediate neighborhood. This causes characteristic sinusoidal absorption features in the X-ray spectrum of a distant source that depend on the structure of the absorbing solid material.

Another, perhaps better known, technique of probing ISM dust, infrared spectroscopy, can also be used to study crystalline dust. However, EXAFS has a major advantage over infrared spectroscopy, in that it can probe the solid matter along the line-of-sight at the level of the atomic structure, even for irregular amorphous materials.

Infrared spectroscopy, by comparison, provides information at the mineralogical level. As a result, using EXAFS, astronomers can obtain a very detailed sampling of the composition and atomic structure of the dust along the line-of-sight. EXAFS gives a more detailed picture of the chemical composition and atomic structure of amorphous grains than is possible with infrared spectroscopy.

Dr. Jennifer Martin | EurekAlert!
Further information:
http://www.obspm.fr

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>