A multi-wavelength high-resolution study of the S255 star-forming region: general structure and kinematics

Abstract

We present observational data for two main components (S255IR and S255N) of the S255 high mass star-forming region in continuum and molecular lines obtained at 1.3 mm and 1.1 mm with the Submillimeter Array (SMA), at 1.3 cm with the Very Large Array, and at 23 and 50 cm with the Giant Metrewave Radio Telescope. The angular resolution was from ~2" to ~5" for all instruments. With the SMA we detected a total of about 50 spectral lines of 20 different molecules (including isotopologues). About half of the lines and half of the species (in particular N₂H⁺, SiO, C³⁴S, DCN, DNC, DCO⁺, HC₃N, H₂CO, H₂CS, SO₂) have not been previously reported in S255IR and partly in S255N at high angular resolution. Our data reveal several new clumps in the S255IR and S255N areas through their millimeter wave continuum emission. Masses of these clumps are estimated at a few solar masses. The line widths greatly exceed expected thermal widths. These clumps have practically no association with NIR or radio continuum sources, implying a very early stage of evolution. At the same time, our SiO data indicate the presence of high-velocity outflows related to some of these clumps. In some cases, strong molecular emission at velocities of the quiescent gas has no detectable counterpart in the continuum. We discuss the main features of the distribution of NH₃, N₂H⁺, and deuterated molecules. We estimate properties of decimeter wave radio continuum sources and their relationship with the molecular material.