Stellar Properties from NLTE Radiative Transfer

Stellar spectra encode a large amount of physical information, such as a star's mass, temperature, radius, age, distance, velocity field, and detailed elemental composition. Stellar spectroscopy is used not just to study the properties of stars, but also to learn about the history of our Milky Way galaxy, the origin of elements and cosmic nucleosynthesis, the nature of dark matter, and the properties of extrasolar planets. The most common stellar atmosphere models assume Local Thermodynamic Equilibrium (LTE). These improved - more physically-complete - NLTE models are necessary to obtain accurate chemical abundances and stellar parameters, but they are still not widely adopted, because of their computational expense and limited availability.

The goals of this workshop are to (1) advance and promote collaborations in NLTE modeling of stellar spectra, with a focus on developing a framework to make these more accurate physical models more widely available and easily accessible to community; and (2) develop new projects and collaborations for applying these methods to determine chemical abundances of metal-poor stars in the Milky Way and in dwarf galaxies (i.e., in the regime where NLTE effects are known to be important for the interpretation of chemical abundance ratios). 

This workshop of ~40 people will cover three general themes: (A) physics and numerics of NLTE radiative transfer, atomic data, and 3D atmospheres; (B) applications to metal-poor stars, dwarf galaxies, and spectroscopic surveys; and (C) pipelines and machine learning. There will be a mix of short talks and time for small discussions or working on specific activities.

Location: University of Chicago, Chicago, IL, USA

Dates: 3.5 days, morning of Tuesday, May 30, 2023 to mid-day on Friday, June 2, 2023.

Travel: University of Chicago is accessible by cab, rideshare, or public transit from O'Hare International Airport (ORD) or Midway International Airport (MDW).

Accommodations: A list of suggested nearby hotels is at this link: https://visit.uchicago.edu/accommodations/. We note the accommodations are slightly pricey at this time of year due to graduation festivities, and you may prefer to stay in Chicago downtown which is a 30-40 minute commute away on public transit.

Acknowledgments: This workshop is supported by the National Science Foundation under Grant No. OISE-1927130 (IReNA), the Kavli Institute for Cosmological Physics (KICP), and the University of Chicago Data Science Institute.

Organizers: Alex Ji (University of Chicago), Rana Ezzeddine (University of Florida), Maria Bergemann (MPIA)