A Multi-Wavelength High Resolution Study of the S255 Star Forming Region. General structure and kinematics

TL;DR

This study provides a detailed multi-wavelength high-resolution analysis of the S255 star-forming region, revealing new molecular lines, clumps, and outflows, and offering insights into the early stages of high-mass star formation.

Contribution

It presents new high-resolution molecular line data and continuum observations of S255, identifying previously unreported molecules and clumps, and analyzing their physical and kinematic properties.

Findings

Discovered about 50 spectral lines of 20 molecules, including new detections.

Identified new clumps with masses of a few solar masses, mostly in early evolutionary stages.

Detected high-velocity outflows and molecular emission without continuum counterparts.

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 SMA, at 1.3 cm with the VLA and at 23 and 50 cm with the GMRT. 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 by 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.