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.

Brief CV of Dr. Riccardo Cesaroni:

His main interest is the study of galactic star formation through observations of molecular and ionized gas. In particular, the focus of his research is on young early-type stars with special attention to circumstellar disks, jets, and HII regions. As a radioastronomer, he has been intensively using both single-dish telescopes and
interferometers from centimeter to sub-millimeter wavelengths.