Letters of Intent received in 2022

LoI 2024-2169
Connecting the scales: Synthesizing populations from individual stars

Date: 5 August 2024 to 6 August 2024
Category: Focus meetings (GA)
Location: Cape Town (IAU GA 2024), South Africa
Contact: Andreas Sander (andreas.sander@uni-heidelberg.de)
Coordinating division: Division G Stars and Stellar Physics
Other divisions: Division D High Energy Phenomena and Fundamental Physics
Division H Interstellar Matter and Local Universe
Division J Galaxies and Cosmology
Co-Chairs of SOC: Stephane Charlot (Institut d'Astrophysique de Paris)
Miriam Garcia (Centro de Astrobiologia, CSIC-INTA)
Kathryn Kreckel (Universitaet Heidelberg)
Lida Oskinova (Universitaet Potsdam)
Aida Wofford (Universidad Nacional Autónoma de México (UNAM))
Chair of LOC: None (None)



* A panchromatic view on massive stars and their feedback
* Confronting stellar models with ISM diagnostics
* Massive post-interaction binaries: From predictions to observations
* The impact of binary and multiple evolution on population synthesis
* Connecting the stellar and the pc-scale with SALT and the LVM
* Tracing the multi-scale impact of massive star feedback
* The legacy of ULLYSES and XShootU and next-generation UV surveys
* Opportunities for ground-based spectroscopy of metal-poor stars with SALT, VLT and ELT
* The next steps for atmosphere and evolution models to explain young stellar populations



As the engines of the cosmic matter cycle, young stellar populations are a central pillar in our perception of the chemical and dynamical evolution of clusters, galaxies, and even our Universe as a whole. In them, massive stars dominate the radiative and mechanical input of the populations into the ISM, leaving traceable signatures also in unresolved external galaxies. The proper modeling and interpretation of these signatures will be vital in this beginning new era of instrumentation with the recently launched JWST and new flagship telescopes like the ELT and SKA on the horizon. Yet, these efforts are hampered by the often quite limited connection between the analysis of unresolved stellar populations on the one hand and our individual understanding of resolved clusters, massive star evolution, and feedback on the other hand.

The GA in South Africa is the ideal place for this meeting with the local South African astronomical community being strongly involved into both theoretical and observational aspects of stellar feedback. With the 10m-class South African Large Telescope (SALT), one of the vital facilities at optical wavelengths for making breakthroughs in explaining stars and their ionizing feedback is also located in the hosting country. Soon, the Square Kilometre Array (SKA) will provide an amazing addition at longer wavelengths. Reaching a resolution we now only have at sub-mm wavelengths due to ALMA, this new radio eye will yield unprecedented insights into various crucial stages of stellar feedback, including the strong winds from evolved massive stars and the earliest stages of young stellar stellar populations which are still heavily enshrouded, but have detectable outflows in the radio regime.

In the proposed Focus Meeting, we want to determine what is needed to obtain a more realistic insight and treatment of young stellar populations. With the availability of high-resolution and multi-epoch spectroscopy, we are now more and more able to dissect the inherent multiplicity among massive stars. New generations of stellar atmosphere and structure modeling lead us to reconsider long-standing assumptions about the properties and evolution of massive stars, in particular in the context of predicting and interpreting stellar properties and feedback after stages of mass transfer. The meeting is timely not only in its preparatory science for future telescopes, but also making use of the insights produced by the ULLYSES and XShootU legacy observations as well as the start of the SDSS-V Local Volume Mapper (LVM) spectroscopic survey, which will provide new, direct feedback measurements in the Milky Way and other Local Group galaxies.