Μάθημα : Ενημέρωση φοιτητών κατεύθυνσης Αστροφυσικής
Κωδικός : PHYS352
Έκτακτη ομιλία Αστροφυσικής - Παρασκευή 15/05/26 - 16:00
Speaker: Lennart Böhm (ESO, Germany)
Accretion, Feedback, and Gas Dynamics Across Scales in the Massive Star-Forming Region W33 Main
Massive stars play a fundamental role in galactic evolution through their radiative, mechanical, and chemical feedback, yet how they assemble their mass remains one of the central open questions in star formation. A key issue is whether accretion can continue in the presence of strong stellar feedback, and how efficiently mass is transferred across spatial scales and gas phases. In this talk, I will present a spectroscopic, multi-wavelength study of the massive star-forming region W33 Main, where several filaments converge toward compact HII regions on scales of ~0.1 pc.
Using new high-resolution ALMA observations reaching ~100 AU scales, together with archival ALMA, VLA+GBT, and VLT/KMOS data, we trace the connection between dense molecular gas, ionized gas, and shocked material from parsec scales down to the immediate surroundings of young massive stars. The combination of molecular lines, ammonia, radio recombination lines, and near-infrared emission lines provides a unified view of the gas kinematics, excitation, and phase structure.
We identify coherent inflows from the surrounding filaments into the central hub and toward embedded sources, while tracers of ionized and shocked gas reveal how feedback interacts with the accreting material. In particular, the data show that accretion and feedback coexist over a wide range of spatial scales, including the interface with ultra- and hyper-compact HII regions and a champagne-like flow emerging from the hub.
To characterize the physical structure of the region in a uniform framework, we analyze the molecular spectral cubes with pixel-based XCLASS modeling, deriving spatially resolved temperatures, column densities, and kinematics across multiple species. Combined with radio and near-infrared spectroscopy, this allows us to connect the dynamics of the molecular, ionized, and shocked gas components and to assess how mass is redistributed between them.
These results provide observational constraints on accretion efficiency, mass loading, and the coupling between inflow and feedback during massive star formation. More broadly, W33 Main serves as a resolved benchmark for simulations that aim to capture the interplay between accretion, ionization, and outflows in forming massive stars and clusters. It also offers an important local reference for interpreting unresolved or partially resolved feedback and gas-transport signatures in extragalactic star-forming regions.