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20.08.2019 – 13:26

Technische Universität München

Stardust in the Antarctic snow provides information on the environment of the solar system

TECHNICAL UNIVERSITY OF MUNICH

Corporate Communications Center

phone: +49 89 289 10516 - email: presse@tum.de - web: www.tum.de

This text on the web: https://www.tum.de/nc/en/about-tum/news/press-releases/details/35654/

High-resolution pictures: https://mediatum.ub.tum.de/1518357

NEWS RELEASE

Stardust in the Antarctic snow

Iron-60 discovery in the Antarctic provides information on the environment of the solar system

The rare isotope iron-60 is created in massive stellar explosions. Only a very small amount of this isotope reaches the earth from distant stars. Now, a research team with significant involvement from the Technical University of Munich (TUM) has discovered iron-60 in Antarctic snow for the first time. The scientists suggest that the iron isotope comes from the interstellar neighborhood.

The quantity of cosmic dust that trickles down to Earth each year ranges between several thousand and ten thousand tons. Most of the tiny particles come from asteroids or comets within our solar system. However, a small percentage comes from distant stars. There are no natural terrestrial sources for the iron-60 isotope contained therein; it originates exclusively as a result of supernova explosions or through the reactions of cosmic radiation with cosmic dust.

Antarctic snow travels around the world

The first evidence of the occurrence of iron-60 on Earth was discovered in deep-sea deposits by a TUM research team 20 years ago. Among the scientists on the team was Dr. Gunther Korschinek, who hypothesized that traces of stellar explosions could also be found in the pure, untouched Antarctic snow. In order to verify this assumption, Dr. Sepp Kipfstuhl from the Alfred Wegener Institute collected 500 kg of snow at the Kohnen Station, a container settlement in the Antarctic, and had it transported to Munich for analysis. There, a TUM team melted the snow and separated the meltwater from the solid components, which were processed at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) using various chemical methods, so that the iron needed for the subsequent analysis was present in the milligram range, and the samples could be returned to Munich.

Korschinek and Dominik Koll from the research area Nuclear, Particle and Astrophysics at TUM found five iron-60 atoms in the samples using the accelerator laboratory in Garching near Munich. "Our analyses allowed us to rule out cosmic radiation, nuclear weapons tests or reactor accidents as sources of the iron-60," states Koll. "As there are no natural sources for this radioactive isotope on Earth, we knew that the iron-60 must have come from a supernova."

Stardust comes from the interstellar neighborhood

The research team was able to make a relatively precise determination as to when the iron-60 has been deposited on Earth: The snow layer that was analyzed was not older than 20 years. Moreover, the iron isotope that was discovered did not seem to come from particularly distant stellar explosions, as the iron-60 dust would have dissipated too much throughout the universe if this had been the case. Based on the half-life of iron-60, any atoms originating from the formation of the Earth would have completely decayed by now. Koll therefore assumes that the iron-60 in the Antarctic snow originates from the interstellar neighborhood, for example from an accumulation of gas clouds in which our solar system is currently located.

"Our solar system entered one of these clouds approximately 40,000 years ago," says Korschinek, "and will exit it in a few thousand years. If the gas cloud hypothesis is correct, then material from ice cores older than 40,000 years would not contain interstellar iron-60," adds Koll. "This would enable us to verify the transition of the solar system into the gas cloud - that would be a groundbreaking discovery for researchers working on the environment of the solar system.

Publication:

D. Koll, G. Korschinek, T. Faestermann, J. M. Gómez-Guzmán, S. Kipfstuhl, S. Merchel, J. M. Welch: Interstellar 60Fe in Antarctica. In: Physical Review Letters 123, 072701. Published 12 August 2019. DOI: 10.1103/PhysRevLett.123.072701

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.072701

High resolution images:

https://mediatum.ub.tum.de/1518357

Contact:

Dr. Gunther Korschinek

Technical University of Munich

Department of Physics

Research Group Experimental Astro-Particle Physics

phone: +49 89 (0) 89 289-14257

korschin@tum.de

Dr. Thomas Faestermann

Technical University of Munich

Department of Physics

Research Group Nuclear Astrophysics

phone: +49 89 (0) 89 289-12438

thomas.faestermann@mytum.de


The Technical University of Munich (TUM) is one of Europe's leading research
universities, with around 550 professors, 41,000 students, and 10,000 academic
and non-academic staff. Its focus areas are the engineering sciences, natural
sciences, life sciences and medicine, combined with economic and social
sciences. TUM acts as an entrepreneurial university that promotes talents and
creates value for society. In that it profits from having strong partners in
science and industry. It is represented worldwide with the TUM Asia campus in
Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, San Francisco,
and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel, Carl von
Linde, and Rudolf Mößbauer have done research at TUM. In 2006, 2012 and 2019 it
won recognition as a German "Excellence University." In international rankings,
TUM regularly places among the best universities in Germany.
More stories: Technische Universität München
More stories: Technische Universität München