Sebastian Ratzenböck
Sebastian Ratzenböck

I am an astrophysicist and data scientist at the Center for Astrophysics | Harvard & Smithsonian. I am interested in star formation, machine learning, and statistics. I work on understanding young stars, stellar clusters, and the Milky Way’s structure using a mix of data analysis and custom-built machine learning tools.

Short Bio

I am an SAO postdoctoral fellow in Catherine Zucker's group, where I am working on constructing the first self-consistent, all-sky 3D census of young stars in the solar neighborhood. This map aims to better constrain the physics of the galactic baryon cycle in a highly resolved volume of the local Milky Way and shed more light on how molecular clouds convert gas into stars, and how feedback from those stars shapes their surrounding environments and regulates subsequent star formation. I am applying modern machine learning methods to integrate data from multiple surveys to infer probabilistic ages and distances, even for stars with incomplete observations.

Formerly, I was an FFG funded postdoc at the Data Science Research Network at the University of Vienna where my goal was to provide a detailed overview of nearby young star clusters and to study the star formation history and build-up of the Scorpius-Centaurus OB association. Our catalog serves as a foundation for future research on critical astrophysical questions, such as the initial mass function, local gas star formation rate, and timescales for star and planet formation.

During my PhD at the Data Science Research Network in Vienna, I have worked with João Alves, Torsten Möller, and Immanuel Bomze to develop tailored machine-learning techniques to identify and characterize stellar clusters in nearby regions of the Milky Way.

Research Positions

Postdoctoral Fellow
2025 - present
Postdoctoral Fellow
2022 - 2025

Education

Doctor of Technology in Data Science (PhD)
2022
Master's Technical Physics (MSc)
2018
Bachelor's Technical Physics (BSc)
2015

Publications

Sebastian Ratzenböck, João Alves, Emily L. Hunt, Núria Miret-Roig, Stefan Meingast, and Torsten Möller
Efrem Maconi, João Alves, Cameren Swiggum, Sebastian Ratzenböck, Josefa E. Großschedl, Peter Köhler, Núria Miret-Roig, Stefan Meingast, Ralf Konietzka, Catherine Zucker, Alyssa Goodman, Marco Lombardi, Gregor Knorr, Gerrit Lohmann, John Forbes, Andreas Burkert, and Merav Opher
Núria Miret-Roig, João Alves, Sebastian Ratzenböck, Phillip A. B. Galli, Hervé Bouy, Francesca Figueras, Josefa Großschedl, Stefan Meingast, Laura Posch, Alena Rottensteiner, Cameren Swiggum, and Nora Wagner
Laura Posch, João Alves, Núria Miret-Roig, Sebastian Ratzenböck, Josefa Großschedl, Stefan Meingast, Cameren Swiggum, and Ralf Konietzka
Cameren Swiggum, João Alves, Robert Benjamin, Sebastian Ratzenböck, Núria Miret-Roig, Josefa Großschedl, Stefan Meingast, Alyssa Goodman, Ralf Konietzka, Catherine Zucker, Emily L Hunt, and Sabine Reffert
Núria Miret-Roig, João Alves, David Barrado, Andreas Burkert, Sebastian Ratzenböck, and Ralf Konietzka
B Bauer-Fasching, K Bernhard, Erik Brändli, H Burger, B Eisele, Stefan Hümmerich, J Neuhold, Ernst Paunzen, Martin Piecka, Sebastian Ratzenböck, and Michal Prišegen
Laura Posch, Núria Miret-Roig, João Alves, Sebastian Ratzenböck, Josefa Großschedl, Stefan Meingast, Catherine Zucker, and Andreas Burkert
Sebastian Ratzenböck, Josefa E. Großschedl, João Alves, Núria Miret-Roig, Immanuel Bomze, John Forbes, Alyssa Goodman, Álvaro Hacar, Doug Lin, Stefan Meingast, Torsten Möller, Martin Piecka, Laura Posch, Alena Rottensteiner, Cameren Swiggum, and Catherine Zucker
Sebastian Ratzenböck, Josefa E. Großschedl, Torsten Möller, João Alves, Immanuel Bomze, and Stefan Meingast
Stefan Meingast, João Alves, Hervé Bouy, Monika G Petr-Gotzens, Verena Fürnkranz, Josefa Großschedl, David Hernandez, Alena Rottensteiner, Magda Arnaboldi, Joana Ascenso, Amelia Bayo, Erik Brändli, Anthony GA Brown, Jan Forbrich, Alyssa Goodman, Álvaro Hacar, Birgit Hasenberger, Rainer Köhler, Karolina Kubiak, Michael Kuhn, Charles Lada, Kieran Leschinski, Marco Lombardi, Diego Mardones, Laura Mascetti, Núria Miret-Roig, André Moitinho, Koraljka Mužić, Martin Piecka, Laura Posch, Timo Prusti, Karla Peña Ramírez, Ronny Ramlau, Sebastian Ratzenböck, Germano Sacco, Cameren Swiggum, Paula Stella Teixeira, Vanessa Urban, Eleonora Zari, and Catherine Zucker
Sebastian Ratzenböck, Verena Obermüller, Torsten Möller, João Alves, and Immanuel Bomze
Natalie Grasser, Sebastian Ratzenböck, João Alves, Josefa E. Großschedl, Stefan Meingast, Catherine Zucker, Álvaro Hacar, Charles Lada, Alyssa Goodman, Marco Lombardi, John Forbes, Immanuel Bomze, and Torsten Möller
Sebastian Ratzenböck, Stefan Meingast João Alves, Torsten Möller, and Immanuel Bomze

Selected Talks

Toward the fabric of the Milky Way
MPIA Milky Way group meeting, invited talk, April 2025
Significance Mode Analysis for hierarchical structures: Extracting stellar populations from large-scale surveys
Significance Mode Analysis for hierarchical structures
Significance Mode Analysis for hierarchical structures
Topology and data: recovering multi-scale structures from Gaia EDR3
European Astronomical Society Annual Meeting, contributed talk, June 2021
Searching for what no one is looking for
Artificial Intelligence in Astronomy, contributed talk, July 2019
Exploring the Milky Way with Gaia

Teaching

Lecturer, University of Vienna
2023 - 2025, Teaching the Research Seminar in the Master's curriculum Data Science.
Co-teaching, University of Vienna
2019 - 2025, full list available here.
Visual Data Analysis
2021, Trainer at the Digital Entrepreneurship Innovation LAB, organized by Entrepreneurship @ Uni Vienna
Data Mining in Astronomy
2019, Lecturer at the International Summer School on Deep Learning and Data Science, organized by VSB-TU Ostrava and Data Science @ Uni Vienna

Consulting

ML advisor: Detecting drug smuggling patterns in crime data
2022 - 2023, Project with Prof. Möller and the United Nations Office on Drugs and Crime (UNODC)
Educational Consultant: Machine learning on time series data
2019, Gaiascope, Inc