How much does stardust affect interstellar travel?

There is stardust in the earth that comes from alien suns

Formation of the solar system
Part of the material from which the earth was made was stardust from giant red stars. This is what researchers at ETH Zurich found out.
Iron meteorite that was analyzed at the Institute for Geochemistry and Petrology at ETH Zurich.

You have to know that

  • At the beginning of our solar system, a disk of gas and dust orbited the sun.
  • The planets gradually formed from this gas and dust.
  • The source material also contained exotic dust: stardust from other solar systems.

An interstellar molecular cloud collapsed around 4.5 billion years ago. The sun was created in its center and around it a disk of gas and dust, in which the earth and the other planets were formed.

Exotic dust grains were found in the well-mixed interstellar material. “Stardust that was formed around other suns,” explains Maria Schönbächler, professor at the Institute for Geochemistry and Petrology at ETH Zurich. These dust grains made up only a few percent of the total amount of dust and were unevenly distributed in the disk. "The stardust was like salt and pepper," says the geochemist, who is also a member of the National Research Center PlanetS. When the planets were formed, each got its own mix.



Even today, the researchers can detect the stardust that was present when the solar system was born in the laboratory thanks to high-precision measurement methods. They examine certain chemical elements and measure the proportion of various so-called isotopes. This means different types of atoms of an element, which have the same number of protons but different numbers of neutrons in their nucleus. "The distribution of these isotopes is like a fingerprint," says Maria Schönbächler: "Stardust has very extreme and unique fingerprints and because it was so unevenly distributed, every planet and every asteroid got its own fingerprint when it was formed."

Investigated palladium in meteorites

Researchers have been able to detect these so-called isotopic anomalies in more and more elements over the past ten years when examining rocks and meteorites. Maria Schönbächler's group now investigated meteorites that were originally part of the cores of asteroids that were destroyed a long time ago. She concentrated on the element palladium. Previously, other teams had studied neighboring elements in the periodic table, such as molybdenum and ruthenium. A prediction for the palladium results could be made from this. But the measurements contradicted the prognosis. "The meteorites contained much smaller palladium anomalies than expected," says Mattias Ek, who, among other things, carried out the laboratory measurements at ETH as a doctoral student.

With a new model, the researchers can explain these results, as they are now reporting in the journal “Nature Astronomy”. Due to its composition, the stardust must have mainly originated in red giant stars. These are aging stars that are expanding because their core has run out of fuel. The sun, too, will become a red giant in four to five billion years. In these stars, so-called slow neutron capture processes occur, in which heavier elements such as molybdenum or palladium are formed. “Palladium is somewhat more volatile than the other measured elements, so it condensed less to dust and the amount of palladium from stardust is smaller in the meteorites examined,” explains Mattias Ek.

The ETH researchers also have a plausible explanation for another mystery about stardust. On earth there is comparatively more material from red giants than on Mars or Vesta and other asteroids further out in the solar system. It is more likely that material accumulated there that originated from supernova explosions. “When the planets were formed, the temperatures closer to the sun were quite high,” explains Maria Schönbächler. Therefore, unstable dust grains that had an ice coat, for example, were evaporated. Above all, the interstellar material contained such dust that was destroyed in the vicinity of the sun, while the stardust from the red giants was less labile and therefore accumulated there. Grains from supernova explosions are also likely to evaporate more easily because they are slightly smaller. “We can therefore explain why the signal from stardust that we analyze in the laboratory today comes mainly from red giants and is the largest on earth,” summarizes Maria Schönbächler.

In this summer series on space, higgs presents content that was created as part of the research focus PlanetS. These were published for the first time on the website of the National Center of Competence in Research PlanetS. The research focus PlanetS was launched in June 2014 by the Swiss National Science Foundation. Scientists from the Universities of Bern, Geneva and Zurich, as well as the ETH Zurich and EPF Lausanne are involved.
We depend on you so that we can stay free and ad-free.