VLBI multi-epoch water maser observations toward massive protostars

TL;DR

This paper summarizes VLBI multi-epoch water maser observations of massive protostars, revealing unexpected phenomena and providing new insights into the early stages of high-mass star formation.

Contribution

It presents new observational results that uncover phenomena like pulsed ejections and simultaneous jets and outflows in massive protostars, advancing understanding of their formation processes.

Findings

Detection of non-collimated pulsed ejections in protostars

Observation of simultaneous jet and wide-angle outflow in Cep A HW2

Identification of new star formation centers via outflow activity

Abstract

VLBI multi-epoch water maser observations are a powerful tool to study the gas very close to the central engine responsible for the phenomena associated with the early evolution of massive protostars. In this paper we present a summary of the main observational results obtained toward the massive star-forming regions of Cepheus A and W75N. These observations revealed unexpected phenomena in the earliest stages of evolution of massive objects (e.g., non-collimated "short-lived" pulsed ejections in different massive protostars), and provided new insights in the study of the dynamic scenario of the formation of high-mass stars (e.g., simul- taneous presence of a jet and wide-angle outflow in the massive object Cep A HW2, similar to what is observed in low-mass protostars). In addition, with these observations it has been possible to identify new, previously unseen centers of high-mass star formation through outflow activity.