Clustered star formation at early evolutionary stages. Physical and chemical analysis of the young star-forming regions ISOSS J22478+6357 and ISOSS J23053+5953

TL;DR

This study characterizes the physical and chemical properties of early-stage star-forming cores in two regions, revealing molecular emission patterns, outflows, and shock regions, and estimating chemical timescales to understand early star formation processes.

Contribution

It provides a detailed physical-chemical analysis of very young star-forming regions using multi-wavelength data and modeling, highlighting early chemical timescales and molecular emission correlations.

Findings

Detection of bipolar outflows indicating protostellar activity

Identification of shock regions with specific molecular emissions

Chemical timescales of cores are around 20,000 years, shorter than more evolved sources

Abstract

We aim to characterize the physical and chemical properties of fragmented cores during the earliest evolutionary stages in the very young star-forming regions ISOSS J22478+6357 and ISOSS J23053+5953. NOEMA 1.3 mm data are used in combination with archival mid- and far-infrared observations to construct and fit the SEDs of individual fragmented cores. The radial density profiles are inferred from the 1.3 mm continuum visibility profiles and the radial temperature profiles are estimated from H2CO rotation temperature maps. Molecular column densities are derived with the line fitting tool XCLASS. The physical and chemical properties are combined by applying the physical-chemical model MUSCLE in order to constrain the chemical timescales of a few line-rich cores. The morphology and spatial correlations of the molecular emission are analyzed using the HOG method. The mid-infrared data show that both regions contain a cluster of young stellar objects. Bipolar molecular outflows are observed in the CO 2-1 transition toward the strong mm cores indicating protostellar activity. We find strong molecular emission of SO, SiO, H2CO, and CH3OH in locations which are not associated with the mm cores. These shocked knots can be either associated with the bipolar outflows or, in the case of ISOSS J23053+5953, with a colliding flow that creates a large shocked region between the mm cores. The mean chemical timescale of the cores is lower (20 000 yr) compared to that of the sources of the more evolved CORE sample (60 000 yr). With the HOG method, we find that the spatial emission of species tracing the extended emission and of shock-tracing molecules are well correlated within transitions of these groups.