Many massive stars were once part of binary systems, but their exciting past is often lost – at least it was so far. A new study at the Max Planck Institute for Astrophysics and the University of Bonn has now found a new method to identify stars that once gained mass from a companion – stars that now appear as single objects but carry the chemical scars of their binary youth. Using a unique “chemical fingerprint” – independent of specific evolutionary models – they were able to reconstruct the binary histories of massive stars. The method has already reclassified the well-studied star γ Columbae as a former mass gainer – challenging long-held assumptions about its origin– and offered new insight into the supernova SN 1987A’s progenitor. more

Juma Kamulali is the first astrophysics PhD graduate from Kyambogo University in Uganda. In collaboration with the partner group of the Max Planck Institute for Astrophysics (MPA), he conducted ground-breaking research that introduces a powerful new machine-learning tool, MAISTEP, which enables the precise determination of stellar properties from basic observational data. Applying this method to thousands of exoplanet-host stars, Kamulali discovered a clearer, deeper 'radius valley' between super-Earths and sub-Neptunes, shedding new light on planetary evolution and atmospheric loss. more

In addition to the spectacular black hole systems that produce high-energy transients, there should exist a much larger hidden population of black holes that remain silent and can be detected only through their gravitational influence on companion stars. So far, the ESA Gaia mission has identified three such quiescent black hole binaries, with many more potentially to be released in December this year. However, two of these systems pose a major challenge to our understanding of binary evolution because of their unexpectedly wide orbits and extreme mass ratios. A new study by the Max Planck Institute for Astrophysics proposes a solution: if most of the mass transferred from the massive star escapes the system without carrying away a significant fraction of the orbital angular momentum, the binary can survive without its orbit shrinking or the stars merging. These findings suggest that low-angular-momentum mass loss may also play an important role in other types of systems, with significant implications for our understanding of how binary systems evolve. more

On 8 July, the Max-Planck-Institut für Astrophysik (MPA) honoure two outstanding early-career researchers, Teresa Braun and Aniket Bhagwat, with the Kippenhahn Prize for groundbreaking papers that have significantly advanced our understanding of the Sun and the early universe. The prize, which was established to promote excellence in scientific writing and original thinking, recognizes not only the depth of their discoveries but also the clarity and rigor of their presentation.
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Although dark matter makes up most of the matter in the universe, what it is made of remains one of the biggest open questions in physics. One indirect clue to its particle nature is how clumpy it is on small scales, such as in dwarf galaxies and smaller. The smallest of these clumps are associated with few or no stars and cannot be seen directly; however, their gravity can perturb stellar streams, thin trails of stars that act as sensitive probes. MPA scientists have now demonstrated that analysing both the location and the movement of stellar stream's stars can pinpoint the scale at which dark matter stops clumping several times more precisely, achieving a level of sensitivity comparable to the most advanced methods currently available. more

The IAU has announced the winners of its annual PhD prizes, including MPA postdoc Claude Cournoyer-Cloutier, who was recognised for her thesis on the 'Dynamics and Feedback of Massive Binaries in Young Massive Star Clusters'.
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Today, the European Research Council (ERC) announced that two researchers at the Max Planck Institute for Astrophysics will receive an Advanced Grant to pursue ambitious projects. MPA director Eiichiro Komatsu will investigate New Physics from the Polarized Light of the Cosmic Microwave Background (NewPhysCMB), while Sherry Suyu, who is also a professor at the Technical University Munich, will be constraining the Hubble constant, Supernova Ia progenitors, and emissions of tidally disrupted stars near black holes (LENS-ON-FIRE). In total, 319 leading researchers across Europe were selected to receive funding worth €838 million in the framework of the EU’s Horizon Europe programme. more