DOI

https://doi.org/10.48717/pswt-3n27

Project

RB005

Title

RB005

Abstract

The theory of massive star formation is approaching resolution of some of its major hurdles. An episodic disk-mediated accretion mechanism is now emerging as the most likely process by which massive stars acheive their final masses. However observational evidence is scarce since the proposed "bursts" phases of accretion are expected to comprise less than 2 percent of the star¿s formative years. Only two burst events have been identified to date in massive stars: S255IR and NGC6334I. G358.93-0.03 was identified as the third child in this class by maser monitoring campaigns (via the Maser Monitoring Organisation) and now faces intense observational scrutiny to at various frequencies and facilities from Radio to Infrared. Low opacity and high angular resolution grants radio VLBI a clear advantage in efforts to understand the inner workings of these deeply embedded, minute regions. As part of the ongoing M2O-VLBI project, we propose Target of Opportunity observations to map the 6.7 GHz methanol maser transition to trace the propagation of enhanced radiation field driven by the accretion burst which is happening now in real-time. The maser spectra indicate extreme, daily evolution, necessitating multi-epoch observations. However daily or even weekly VLBI observations are not a realistic demand. As such we have reached out to as many VLBI arrays as possible to contribute any available time to observe the event. Observational constraint of the G358 event will be a global effort in which the EVN can provide invaluable contribution.