Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Interplanetary dust particles: reproducing GEMS-like structure in the laboratory

15.02.2006


In a coming issue, Astronomy & Astrophysics presents new laboratory results that provide some important clues to the possible origins of exotic mineral grains in interplanetary dust. Studying interplanetary grains is currently a hot topic within the framework of the NASA Stardust mission, which recently brought back some samples of these grains. They are among the most primitive material ever collected. Their study will lead to a better understanding of the formation and evolution of our Solar System.


Fig. 1. Image of a GEMS in an interplanetary dust particle. Copyright: NASA


Fig. 2. Iron grain embedded in silicate glass.



Through dedicated laboratory experiments aimed at simulating the possible evolution of cosmic materials in space, C. Davoisne and her colleagues explored the origin of the so-called GEMS (glass with embedded metal and sulphides). GEMS is a major component of the primitive interplanetary dust particles (IDPs). They are a few 100 nm in size and are composed of a silicate glass that includes small, rounded grains of iron/nickel and metal sulphide (Figure 1). A small fraction of the GEMS (less than 5%) have presolar composition and could therefore have an interstellar origin. The remainder have solar composition and may have been formed or processed in the early Solar System. The varied compositions of the GEMS make it difficult to arrive at a consensus regarding their origin and formation process.

The team first postulates that the GEMS precursors originated in the interstellar medium and were progressively heated in the protosolar nebula. To test the validity of this hypothesis a joint experimental project involving two French laboratories, the Laboratoire de Structure et Propriétés de l’Etat Solide (LSPES) in Lille and the Institut d’Astrophysique Spatiale (IAS) in Orsay, was set up. Z. Djouadi, at the IAS, heated various amorphous samples of olivine ((Mg,Fe)2SiO4) under high vacuum and at temperatures ranging from 500 to 750°C. After heating, the samples show microstructures that closely resemble those of the GEMS, with rounded iron nanograins that are seen to be embedded in a silicate glass (Figure 2).


This is the first time that a GEMS-like structure has been reproduced by laboratory experiments. There, they show that the iron oxide (FeO) component of the amorphous silicates has undergone a chemical reaction known as reduction, in which the iron gains electrons and releases its oxygen, to precipitate in a metallic form. Since the GEMS component in IDPs is usually closely associated with carbonaceous matter, the reaction FeO + C --> Fe + CO will be at the source of the metallic iron nanograins in these IDP’s. Such conditions may have been encountered in the primitive solar nebula. This reaction has been known of for centuries by metallurgists, but the originality of the LSPES/IAS approach is the application of material science concepts to extreme astrophysical environments.

In addition, the scientists found that, in the heated sample, practically no iron remains in the silicate glass, since all the iron has migrated into the metal grains. The team is thus able to explain why the dust observed around evolved stars and in comets is mainly composed of magnesium-rich silicates where iron is apparently lacking. Indeed, iron in metallic spherules becomes totally undetectable by the usual remote spectroscopic techniques. This work could therefore provide an important and new insight into the composition of interstellar grains as well.

The team shows that GEMS could form through a specific heating process that would affect grains of various origins. The process may be very common and could occur both in the Solar System and around other stars. The GEMS could thus have diverse origins. Scientists now eagerly await the analysis of grains collected by Stardust to find out for certain that some GEMS truly come from the interstellar medium.

[1] The team includes C. Davoisne, H. Leroux (from LSPES, Lille, France), Z. Djouadi, L. d’Hendecourt, A. P. Jones and D. Deboffle (from IAS, Orsay, France).

Jennifer Martin | alfa
Further information:
http://www.obspm.fr
http://www.edpsciences.org/journal/index.cfm?edpsname=aa&niv1=others&niv2=press_release&niv3=PRaa200603

More articles from Physics and Astronomy:

nachricht When helium behaves like a black hole
22.03.2017 | University of Vermont

nachricht Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
22.03.2017 | International Centre for Radio Astronomy Research

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>