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2007-01-30 [ ]

Physicist to be recognized for helping 'revolutionize astronomy'

Jan. 30, 2007 -- Studying stars has never been so easy, thanks to the tireless efforts and expertise of Ernst K. Zinner, Ph.D., research professor of physics and of earth and planetary sciences, both in Arts & Sciences, at Washington University in St. Louis.

For the past 30-plus years, Zinner has helped develop and fine-tune increasingly sophisticated instruments that allow researchers to get detailed information about circumstellar and interstellar dust — actual stardust — right in their own labs.

These precision instruments use a measurement technique called secondary ion mass spectrometry (SIMS) to determine the isotopic and elemental composition of microscopic samples, such as interplanetary dust particles and meteorite grains that come from stars.
The early versions of these ion microprobes — dating to the 1970s — can measure grains weighing as little as a millionth of a millionth of a gram. The latest SIMS — the NanoSIMS — can measure particles 10 times smaller.

To recognize Zinner's important contributions to the development of SIMS and its many applications in the earth and space sciences, the departments of Physics and of Earth & Planetary Sciences and the McDonnell Center for the Space Sciences, all in Arts & Sciences, are hosting a scientific symposium Feb. 3-4 in Crow Hall, Room 201.
More than 125 researchers worldwide who use SIMS in various disciplines like astrophysics, cosmochemistry, material science and geochemistry will participate in the symposium, titled "SIMS in the Space Sciences: The Zinner Impact."

"When I think about the symposium title — 'The Zinner Impact' — it is very satisfying to realize that I have made an impact on my former students and postdocs and colleagues who are today using SIMS in various fields with important results," said Zinner, who is considered a pioneer in the analysis of stellar dust grains found in primitive meteorites.
"While I have a small family," Zinner continued, "I have an extended scientific family. I was at a conference where a young woman from South America came up to me and identified herself as my 'scientific granddaughter' — that's because she had been a student of one of my former students. I have all kinds of 'grandchildren' out there that I'm not even aware of!"

Decoding ancient messages

The symposium, which will include invited talks and contributed posters, will pay tribute to Zinner while also highlighting the current research that has benefited from SIMS applications.
Among those presenting a talk is Donald D. Clayton, Ph.D., professor emeritus in the Department of Physics & Astronomy at Clemson University.
"Ernst developed the SIMS technology to the point that it was able to revolutionize astronomy," Clayton said. "It did so by proving that solid chunks of stars exist in the interstellar matter, some of which were incorporated into the meteorite mixing pot when the solar system formed from interstellar matter 4.6 billion years ago.
"This is the only technique available to astronomers for 'seeing' stars that ended their own lives before our earth was even born," Clayton continued. "Telescopes cannot measure isotopic ratios in long-dead stars. Each stardust grain is now seen to be an observation of an ancient star that was recorded long ago, some 5 to 9 billion years ago, and that has lain unknown for the intervening time until today. It is as if some ancient astronomer from a presolar civilization observed these ancient stars, and his measurements have just been found! It was long felt impossible to study in our laboratories — as Ernst has done — solid matter that predates the earth.
"Ernst used SIMS to decode these ancient messages of presolar nucleosynthesis and of the evolution of our Milky Way galaxy. This knowledge has revolutionized astronomy."
Using an ion microprobe — for which Zinner helped develop methods to measure proportions of specific isotopes — Zinner and his colleagues in the late 1980s and '90s identified three types of interstellar grains — silicon carbide, graphite and aluminum oxide — and two important stellar sources of the grains.

For more than 10 years, Zinner and Frank J. Stadermann, Ph.D., senior research scientist in physics, helped design and test the NanoSIMS, the latest ion microprobe on the scene that can resolve objects one thousand times smaller than the diameter of a human hair.
At a cost of $2 million, WUSTL acquired the first NanoSIMS in the world in 2000. There are now some 16 worldwide.

Zinner was part of WUSTL's Laboratory for Space Sciences team that reported in a December 2006 issue of Science finding the first stardust particle from a comet. Without the NanoSIMS, the stardust would never have been identified.
A native of Austria, Zinner earned a doctorate in high-energy physics from WUSTL in 1972. He subsequently joined the university's Laboratory for Space Physics and then became a member of the McDonnell Center for the Space Sciences after its establishment in 1975. Among his awards are the prestigious National Academy of Sciences' J. Lawrence Smith Medal and the Meteoritical Society's Leonard Medal.
In addition to the symposium, the journal Meteoritics and Planetary Science will publish a commemorative issue in May dedicated to Zinner. There is no symposium fee, but registration is required. For more details, call Christine Floss, Ph.D., research associate professor in physics and chair of the symposium's organizing committee, at 314-935-6206 or visit http://presolar.wustl.edu/events/zinner2007/.

Source: http://news-info.wustl.edu/news/page/normal/8652.html?emailID=13042

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