Researchers have long assumed that massive stars are born as twins, triplets or even higher multiple systems. Now, for the first time, this has been confirmed by systematic observations. The study, in which our research group was involved in the interpretation of the data obtained, was published in Nature Astronomy.

More information (in German) at: https://www.uni-due.de/2015-01-15-massereiche-sterne-entstehen-als-mehrlinge

The scientific article: https://www.nature.com/articles/s41550-023-02181-9

A remarkable discovery: Together with a team of international scientists, we have discovered a disk around a young star in the Large Magellanic Cloud, a neighboring galaxy to Earth. It is the first time that such a disk has been found outside our galaxy. The new observations show a massive young star that is growing, absorbing matter from its surroundings and forming a rotating disk. The discovery was made with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.

More information: https://www.eso.org/public/news/eso2318/

The scientific article: https://www.nature.com/articles/s41 

This cover page of Nature Astronomy from September 2022 highlights one of our numerical projects on magnetically-driven jets ejected from massive proto-stars.

In this article, our complementary radiation-magneto-hydrodynamic simulations are visually and quantitatively compared to an observed spiralling flow of plasma. This flow structure is expected for a helical magnetic field geometry forming during cloud collapse, star and circumstellar disk formation. 

The observational data is obtained from high-spatial-resolution observations of water masers around the young massive proto-star IRAS21078+5211. To reach this kind of breakthrough spatial resolution, we made use of all telescopes available in the Very Large Baseline Interferometer network (VLBI). The VLBI array combines 26 radio-telescopes distributed across Europe, Asia and the USA.

Red dots are the observed maser spot locations, the bright white circle denotes the expected position of the massive proto-star. Blue-to-white background color resembles the gas mass density obtained from numerical simulations and shows the circumstellar disk forming from infalling material from larger scales. Blue lines present the spiraling streamlines of the gas flow obtained from the numerical simulation.

See Moscadelli et al. (2022)  for further details.

The research topics of our group spans from the interaction physics of dust grains with high-velocity gas flows and radiation to planet formation, star formation, and black hole formation. Besides formation/accretion phenomena, we are also interested in ejection and feedback phenomena in space. In the following, we briefly present some of these topics.

Planet Formation

How does a rocky planetary embrio accrete its primordial gaseous atmosphere from the natal circumstellar disk? What is the final mass, temperature and angular momentum of the gas bound to the rocky core? Under which conditions does the proto-planet evolve into a gas giant? 

We investigate these questions and associated issues in modern planet formation theory by direct numerical simulations of the accretion process (see sketch "Moldenhauer, Kuiper et al. (2021)"). Making use of high-performance computing resources, we embed a gravitationally acting rocky planetary core into a gaseous circumstellar disk and follow the hydrodynamic and thermodynamic evolution of the system in time.

Star Formation and High-Mass Stellar Feedback

How much mass can a star gain by classical gas accretion? How does its intrinsic feedback mechanisms such as proto-stellar jets, radiation pressure, photoionization feedback and H II regions impede its further growth? How do these feedback effects impact the natal environment of the forming massive star?

We investigate these questions and associated issues in modern star formation theory by direct numerical simulations of the star formation process including the various forms of feedback. Most of the feedback effects can be investigated self-consistently, i.e. they are included in the formation scenario via solving for their underlying physical origin such as the magneto-hydrodynamics of jet launching, acceleration, collimation, and propagation.

Besides the feedback mechanisms, we are interested in the details of circumstellar disk formation and evolution, determining the  accretion efficiency of the forming host star. What is the impact of the large-scale environment on specific disk properties? How does disk formation and evolution differ across the stellar mass range?

Link to group leader's publication lists (automatically created):

Rolf Kuiper @ NASA/ADS

Rolf Kuiper @ ORCiD

Rolf Kuiper @ Google Scholar

Over the years, our research projects have been supported by a variety of grant funding schemes. We gratefully acknowledge financial support by the following institutions and programmes: