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 Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland

nachricht On the shape of the 'petal' for the dissipation curve
23.04.2018 | Lobachevsky University

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: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>