The properties and distribution of molecular clouds in the outer Galaxy: bridging the gap between the Milky Way and nearby galaxies

• Applicant: Professor Dr. Frank Bigiel
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564223364

Molecular clouds are the birthplaces of stars, making their detailed characterization essential for understanding star formation. While molecular clouds in the inner Galaxy (1st and 2nd Galactic quadrants) have been extensively studied, the outer Galaxy remains relatively unexplored. It offers a unique opportunity to investigate, whether star formation proceeds differently under the distinctly different physical conditions in the “outskirts” of the Milky Way, in particular also compared to the inner Galaxy. This project will fund a PhD student to conduct a comprehensive study of molecular clouds in the outer Milky Way, leveraging two key resources: (i) new data from the Outer Galaxy High-Resolution Survey (OGHReS), a 1000 hour, large APEX project mapping over 100 square degrees of the 3rd Galactic quadrant in carbon monoxide (CO) emission lines, and (ii) advanced cloud identification and characterization techniques developed by our group. The work plan will involve identifying molecular clouds within the OGHReS dataset using a machine learning-based algorithm, cataloguing their global properties, and analysing relationships among them. This includes examining resolved cloud features, such as morphology and internal structure, and investigating how these properties connect to star formation processes. A key focus will be comparing the properties of outer Galaxy clouds to those in the inner Galaxy and comparing to those in other, nearby galaxies, where the past few years have seen an explosion of such measurements in, by now, close to 100 galaxies. This project not only fills a significant gap in our understanding of star formation in our own Galaxy, but also provides new, timely and intriguing opportunities to link large-scale Galactic structure to the small-scale processes governing the formation of stars and to bridge measurements in the Milky Way to those in other, local galaxies.

• DFG Programme: Research Grants
• International Connection: Poland, United Kingdom
• Co-Investigator: Dr. Dario Colombo
• Cooperation Partners: Dr. Ana Duarte Cabral; Dr. Agata Karska; Professor Dr. James Urquhart