Methanol and excited OH masers in HMYSOs at milliarcsecond scales

Abstract

Significant contributions to our knowledge of high-mass star formation came from interferometric observations of cosmic masers, mostly from OH, methanol and water molecules. Using the European VLBI Network, our team in Torun has been studying high-mass young stellar objects by imaging the maser lines for over 13 years. Here, we present first milliarcsecond images of G20.237$+$00.065 and G24.148$-$00.009 at the excited OH maser line at 6.035 GHz. These regions were mapped at the 6.7~GHz methanol maser transition earlier as well. Radial velocities of methanol and excited OH spectral features overlapped, as it was noticed in the single-dish spectra. This suggests that both lines arise in the same volume of gas, and VLBI data are necessary to verify this hypothesis.