Search

We present high-spatial resolution (0.7–1.0 arcsec) submillimeter observations of continuum and molecular lines of CH |$_{3}$| OCHO, CH |$_{3}$| OCH |$_{3}$|⁠ , and H |$_{2}$| CCO toward 11 high-mass star-forming regions using the Atacama large millimetre/submillimetre array (ALMA). A total of 19 separate cores from nine high-mass star-forming regions are found to be line-rich, including high-, intermediate-, and low-mass line-rich cores. The three molecules are detected in these line-rich cores. We map the emission of CH |$_{3}$| OCHO, CH |$_{3}$| OCH |$_{3}$|⁠ , and H |$_{2}$| CCO in nine high-mass star-forming regions. The spatial distribution of the three molecules is very similar and concentrated in the areas of intense continuum emission. We also calculate the rotation temperatures, column densities, and abundances of CH |$_{3}$| OCHO, CH |$_{3}$| OCH |$_{3}$|⁠ , and H |$_{2}$| CCO under the local thermodynamic equilibrium assumption. The abundances relative to H |$_{2}$| and CH |$_{3}$| OH, and line widths of the three molecules are significantly correlated. The abundances relative to H |$_{2}$|⁠ , temperatures, and line widths of the three molecules tend to be higher in cores with higher mass and outflows detected. The possible chemical links of the three molecules are discussed. [ABSTRACT FROM AUTHOR]

Investigating the temperature and density structures of gas in massive protoclusters is crucial for understanding the chemical properties therein. In this study, we present observations of the continuum and thioformaldehyde (H2CS) lines at 345 GHz of 11 massive protoclusters using the Atacama Large Millimeter/submillimeter Array telescope. High spatial resolution and sensitivity observations have detected 145 continuum cores from the 11 sources. H2CS line transitions are observed in 72 out of 145 cores, including line-rich cores, warm cores, and cold cores. The H2 column densities of the 72 cores are estimated from the continuum emission, which are larger than the density threshold value for star formation, suggesting that H2CS can be widely distributed in star-forming cores with different physical environments. The rotation temperature and column density of H2CS are derived using the XCLASS software. The results show that the H2CS abundances increase as temperature rises and higher gas temperatures are usually associated with higher H2CS column densities. The abundances of H2CS are positively correlated with its column density, suggesting that the H2CS abundances are enhanced from cold cores, warm cores, and line-rich cores in star-forming regions. [ABSTRACT FROM AUTHOR]