Kirsten Kraiberg Knudsen/Dust particle illustration
Left: ​A scanning electron microscope image of an interplanetary dust particle.​ Right: Kirsten Kraiberg Knudsen, Chalmers University of Technology. 

​On dusty roads through the Universe

Cosmic dust grains are microscopic particles that affect virtually every process in the Universe, from the formation of planets and stars to black holes and entire galaxies. But where do the dust grains come from, and how do they develop? Researchers from Chalmers University of Technology and the University of Gothenburg will try to answer this in a joint project, thanks to a large grant from the Knut and Alice Wallenberg Foundation.
– Dust is absolutely fundamental for astronomy and for us humans. Without dust, our Solar  system would not have formed, says Kirsten Kraiberg Knudsen, head of the project "The Origin and Fate of Dust in our Universe".​
The Knut and Alice Wallenberg Foundation has granted a total of SEK 541 million to 18 outstanding basic research projects in medicine, science and technology that are considered to have the opportunity to lead to future scientific breakthroughs.
Kirsten Kraiberg Knudsen is a professor of extragalactic astronomy at the Department of Space, Earth and Environment at Chalmers and she is very much looking forward to starting the project together with her colleagues.

– It feels fantastic and it is a great opportunity! We are four researchers leading the project: Susanne Aalto, Wouter Vlemmings and myself from Chalmers, together with Gunnar Nyman from the University of Gothenburg. The fact that we can combine our expertise special competencies in this project means that we can cross subject boundaries to address deal with a very fundamental question in astronomy, namely "what is the origin and fate of dust in the Universe".

For non-astronomers, dust is mostly something that gets in the way. Why is it important to study dust in the Universe?

– Dust is fundamental for astronomy and for the formation of our own planet.  Dust particles are small, and complex both in shape and composition, and they are important for most processes in the Universe. For example, dust particles are necessary for star and planet formation – without dust, our Solar system would not have formed. Dust is also important for chemical processes, because an incredible number of many molecules in space are formed on the surface of the dust particles, i e it is difficult for many molecules to form without the dust particles. And dust also affects our observations since dust grains extinct the light from the objects we want to observe, which can have major consequences for the interpretation of scientific results.

In the project you will combine new observations with theoretical models in physical chemistry. What type of objects will you focus on?

– We will focus  on three important types of objects. One of these types is the old stars, around which the seeds of the dust grains originate. Dust grains from stars will subsequently grow in space, when molecules stick to their surfaces. The step from the formation of dust grains to when they are spread throughout the galaxy can be complicated, and the dust can be destroyed by, for example, collisions or radiation.

– We will  also focus on two types of objects that have extreme conditions, galaxies in the early universe, and the regions around supermassive black holes. In the early universe, young galaxies, with lots of dust, have been discovered, while in such young galaxies, most stars have not grown to an age where they produce enough dust. Around supermassive black holes the dust grains are destroyed, reshaped and regrown as the density of the gas and radiation is more extreme than in ordinary parts of a galaxy.

How can theoretical models complement the observations?

– The theoretical models and calculations are intended to describe the dust particles at a microscopic level. Because it is difficult or impossible to perform experiments on Earth that correspond to the extreme conditions that apply found in space, theoretical calculations become extra important. They are intended to help interpret and understand the observations we make.

– One goal of the project is also to understand how the microscopic properties of dust grains affect the larger scale astronomical processes, and the other way around – how macroscopic processes affect the dust grains. An example of this is the survival of dust grains under extreme conditions. 

Is there a specific question that you are especially looking forward to the project succeeding in answering?

– This is a complex research topic with many aspects, so and there are several fascinating questions that I hope we succeed in answering. We want to answer what happens to dust grains after they have formed near dying stars and then transported through space, where the grains need to grow before they can become part of new stars and planets. Based on this, it will be interesting how this compares to galaxies in the previous early universe and in the environment around super-massive black holes.

– If we succeed in this, we will have made an important contribution to the topic. This combination of research fields, observations and theory will impact our understanding of the Universe, the origin and evolution of stars and galaxies and not least our own origins, says Kirsten Kraiberg Knudsen. 

Project: ”The Origi​​n and Fate of Dust in our Universe”

Awarded grant: 27 700 000 SEK for a five year project. 
Professor Kirsten Kraiberg Knudsen, Chalmers University of Technology, together with colleagues professors Wouter Vlemmings and Susanne Aalto, all three at the division of Astronomy and Plasma Physics, the depart ment of Space, Earth and Environment, and professor Gunnar Nyman, Department of Chemistry & Molecular Biology, The University of Gothenburg.

Out of the 18 projects receiving grants from The Knut and Alice Wallenberg Foundation, three will be conducted at Chalmers. At the Department of Physics, Associate Professor Andreas Heinz will lead a project about the creation of heavy elements in neutron-star mergers and Professor Mikael Käll will lead a project on light sources of the future

Photo cre​dits: ​

Top left: A scanning electron microscope image of an interplanetary dust particle. Credit: Donald E. Brownlee, University of Washington, Seattle, and Elmar Jessberger, Institut für Planetologie, Münster, Germany. Original photo and more information can be found here
Top right: Kirsten Kraiberg Knudsen. Credit: Markus Marcetic/Sveriges unga akademi​
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Published: Wed 30 Sep 2020.