We use the European VLBI Network (www.evlbi.org), whose part is the 32 m radio telescope of NCU, in order to make images of methanol maser emission at 6.7 GHz (4.5 cm) with a milliarcsecond resolution (i.e. 10-7 deg). The aim of this project is to make „invisible visible”. The environment in high-mass star-forming region is so dense that the light from a borning star cannot reach us and provide information on what is happening out there. Only indirect methods let us learn mechanisms related to the early stages of the high-mass star evolution. Using methanol masers we can see how the matter around high-mass young stars is moving around.
Spectral line observations allow us to „scan” selected region along the line-of-sight and obtain its three dimensional image. Below, we present consecutive spectral channels of a maser cloud in G22.435-00.169 (the name is after the Galactic coordinates of the target). Its size at each spectral channel map ranges from 12 AU to 40 AU (1AU = 150 000 000 km).
The spectrum and the image of the whole methanol maser emission in G22.435-00.169 are presented below. One can clearly see an elliptical distribution of maser clouds. It suggests their physical relation to a molecular torus or a circumstellar disc. The central object – a massive young star – is invisible, however, the radio emission indicates its existence nearby; either inside the ellipse locating masers in the circumstellar disc or outside indicating that the masers are realted to an outflow.
The image gallery of more targets are here: