Antonio Armeni, INAF – Osservatorio Astronomico di Capodimonte, Naples, Italy — July 6, 2026

Low-mass star formation proceeds through a sequence of evolutionary stages, from deeply embedded protostars (Class 0/I) to optically visible T Tauri stars (Class II), during which the interplay between accretion and ejection shapes both the nascent star and its surrounding disk. In this talk, I present observational results spanning this full evolutionary sequence, combining infrared and optical diagnostics to probe accretion and outflow physics across multiple scales and evolutionary stages.

Starting from the earliest protostellar phase, I discuss how rare accretion outbursts in Class 0 objects can be caught and characterized through multi-wavelength follow-up triggered by methanol maser flares, using the unique capabilities of the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA). Moving to Class I sources, I present high-angular-resolution integral field spectroscopy with the Enhanced Resolution Imager and Spectrograph (ERIS) at the Very Large Telescope (VLT) that spatially and spectrally resolves co-existing jets and disk winds, probing the magneto-centrifugal launching mechanism and the angular momentum removal from the disk. Finally, for Classical T Tauri Stars, I combine high-cadence photometry and high-resolution optical spectroscopy to study the variability of magnetospheric accretion and characterize the outflow components responsible for spinning down the central star.

Together, these results highlight the power of combining infrared and optical observations across a wide range of spatial scales to build a coherent picture of how accretion and ejection co-evolve from the earliest embedded stages through the optically visible pre-main-sequence phase.