The formation of the most massive stars has since ever been an astrophysical puzzle, as their powerful radiation pressure should soon quench the infall of material from the parental cloud. Recent theoretical and observational studies indicate that accretion through a disk+jet system can be a viable solution of the problem. This process is unlikely to occur smoothly as a constant flow in time, but it could consist of episodic accretion events possibly detected as bursts at IR wavelengths. Indeed, recently a sudden increase of IR luminosity by a factor ~5.5 has been detected from the 20 Msun
young stellar object S255 NIRS3. This has been extensively studied by us in a number of tracers. For the first time, we have revealed a burst (and monitored the subsequent expansion) of the radio jet associated with the source, with a delay of about 1 yr after the IR outburst. JVLA and ALMA observations allowed us to derive the jet properties by modelling its evolution in space and time. Our findings strongly support the crucial role of episodic accretion+ejection events in the formation of early-type stars.

Breve CV del Dr. Riccardo Cesaroni:

Il suo principale interesse è lo studio della formazione delle stelle della nostra galassia attraverso l'osservazione di molecole e gas ionizzato. In particulare, il focus della sua ricerca è sulle giovani stelle early-type con speciale attenzione ai dischi circumstellari, getti, e regioni HII. Come radioastronomo, ha fatto uso sia di telescopi single-dish che di interferometri da lunghezze d'onda del centimetrico al sub-millimetrico.