Investigation of H2O and OH Masers in the Region of Formation of a Young High-Mass Stellar Object (S255 NIRS 3)

Abstract

The results of research of a star formation region S255 IR, where a young high-mass star is forming (\(20{\kern 1pt} {{M}_{ \odot }}\)) are presented. Observations in H₂O were carried out with RT-22 in Pushchino, and in the OH lines with the Large Radio Telescope in Nance (France). We used observations in the H₂O line at 1.35 cm for the time interval from 2017 to 2023. Our observations in H₂O showed the presence of strong flares, especially in 2023. A drift of the source emission along the radial velocity was also observed for most spectral features and predominantly with a tendency to decrease the radial velocity. In OH lines at 18 cm in 2008 no emission was detected. We observed OH emission in the main lines at 1665 and 1667 MHz in 2015, 2023, and 2024. Structures of spectra, degrees of circular and linear polarizations varied greatly during these epochs. However, the longitudinal magnetic field vectors had predominantly two directions \( \sim {\kern 1pt} \pm {\kern 1pt} (30^\circ {-} 40^\circ )\) relative to the vertical, i.e. almost perpendicular to the jet or along it. Zeeman splitting was detected only in the 1667 MHz line for one pair of features: 2.26 and 2.37 km/s. The splitting value of 0.11 km/s corresponds to a longitudinal magnetic field value of 0.31 mGs; the field is directed towards the observer. It is assumed that the appearance of OH maser emission in 2015 associated with an accretion flares. Significant structure changes of OH spectra, their degrees of polarization and very strong flares of H₂O maser in 2023 may be associated with a new possible accretion flares in S255 IR.