Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers discover carriers of astronomical 2175 extinction line in presolar grains

14.01.2005


Turn out the light!

A collaborative team of researchers has discovered what turns the lights out from space. Using sophisticated features on a transmission electron microscope, John P. Bradley, Ph.D., Director of the Institute for Geophysics and Planetary Physics at Lawrence Livermore National Laboratory, has discovered that organic carbon and amorphous silicates in interstellar grains embedded within interplanetary dust particles (IDPs) are the carriers of the astronomical 2175 Å extinction line.

Discovered by astronomers more than 40 years ago, the astronomical extinction line occurs at a wavelength of 2175 Angstroms, blocking light from stars from reaching the Earth due to the absorption of light by dust in the interstellar medium. One Angstrom (Å ) is one one-hundred millionth of a centimeter.



Bradley analyzed interstellar grains from the Laboratory for Space Sciences at Washington University in St. Louis to make the discovery.

Last year, Frank Stadermann, Ph.D., Washington University senior research scientist in physics, and Christine Floss, Ph.D., Washington University senior research scientist in earth and planetary sciences and physics, both in Arts & Sciences, reported that some grains within IDPs are presolar in origin. They used a unique instrument called the NanoSIMS – a type of secondary ion mass spectrometer – to measure the isotopic composition of the grains to determine these findings.

The NanoSIMS enables researchers to analyze particles at much higher spatial resolution than before, allowing them to find the small presolar grains within the dust particles. Until recently, ion microprobes could only analyze dozens of such sub-grains at one time and so were able to deduce only the average properties of a sample.

The findings were reported in the Jan. 14, 2005 issue of Science.

Collaborators on the discovery include researchers from the University of California at Davis, Lawrence Berkeley National Laboratory and NASA-Ames Research Center "Interstellar dust for some reason absorbs light at this frequency, and it has been difficult to pinpoint what the source of the absorption is," said Stadermann.

"The strange thing about this feature is that it was observed in different dust clouds and the peak width of the feature was variable, but the center of the peak was always exactly at 2175 Å. People tried to reproduce this in the laboratory on graphite, for example, and they couldn’t get exactly the right absorption peak. It was difficult to find the material responsible for this absorption. Now, for the first time, it can be said we have it."

Livermore’s Bradley used a state-of-the-art transmission electron microscope equipped with a monochromator and a high-resolution electron energy-loss spectrometer, allowing him to analyze in the 2175 Å range, to get exactly the same type of absorption feature in these dust particles.

"The interesting thing is that Bradley and his colleagues found the absorption feature in exactly those places in the IDPs that we have identified as presolar in origin," Stadermann said. "That is a good indication that what the astronomers have been seeing for the last 40 years is the same thing we now observe in these IDPs."

Floss said that Bradley’s discovery is significant because organic carbon and amorphous silicates are abundant in interstellar dust clouds and abundant carriers are needed to account for the fact that the 2175 Å feature is so commonly observed by astronomers. The Washington University contribution is important because the NanoSIMS measurements prove that these grains in the IDPs are actually presolar. This shows that this material has a direct connection to interstellar dust clouds and is not just something from the solar system that coincidentally shows the same extinction feature.

"We originally sent the IDPs to Bradley so that he could identify the presolar phases that we had found, "Floss said. "With this new technique he then made more measurements and made this discovery."

In 2000, with help from NASA and the National Science Foundation, Washington University bought the first commercially available NanoSIMS. Made by Cameca in Paris, the NanoSIMS ion microprobe can resolve particles as small as 100 nanometers in diameter. A million such particles side-by-side would make a centimeter. The presolar grains in IDPs range from 100 nanometers to 500 nanometers.

Christine Floss | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Physics and Astronomy:

nachricht Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>