Complex molecules in W51 North region

Abstract

We present Submillimeter Array (SMA) molecular line observations in two 2 GHz-wide bands centered at 217.5 and 227.5 GHz, toward the massive star forming region W51 North. We identified 84 molecular line transitions from 17 species and their isotopologues. The molecular gas distribution of these lines mainly peaks in the continuum position of W51 North, and has a small tail extending to the west, probably associated with W51 d2. In addition to the commonly detected nitrogen and oxygen-bearing species, we detected a large amount of transitions of the Acetone (CH${}_3$COCH${}_3$) and Methyl Formate (CH${}_3$OCHO), which may suggest that these molecules are present in an early evolutionary stage of the massive stars. We also found that W51 North is an ethanol-rich source. There is no obvious difference in the molecular gas distributions between the oxygen-bearing and nitrogen-bearing molecules. Under the assumption of Local Thermodynamic Equilibrium (LTE), with the XCLASS tool, the molecular column densities, and rotation temperatures are estimated. We found that the oxygen-bearing molecules have considerable higher column densities and fractional abundances than the nitrogen-bearing molecules. The rotation temperatures range from 100 to 200 K, suggesting that the molecular emission could be originated from a warm environment. Finally, based on the gas distributions, fractional abundances and the rotation temperatures, we conclude that CH${}_3$OH, C${}_2$H${}_5$OH, CH${}_3$COCH${}_3$ and CH${}_3$CH${}_2$CN might be synthesized on the grain surface, while gas phase chemistry is responsible for the production of CH${}_3$OCH${}_3$, CH${}_3$OCHO and CH${}_2$CHCN.

accepted to MNRAS

References in corpus (11)

• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• Herschel observations of EXtraordinary Sources: Analysis of the full Herschel/HIFI molecular line survey of Sagittarius B2(N)
• A new study of an old sink of sulfur in hot molecular cores: the sulfur residue
• H-atom bombardment of CO2, HCOOH and CH3CHO containing ices
• SMA millimeter observations of Hot Molecular Cores
• Comparative study of complex N- and O-bearing molecules in hot molecular cores
• Forming an Early O-type Star Through Gas Accretion?
• S-bearing molecules in Massive Dense Cores
• ALMA reveals a candidate hot and compact disk around the O-type protostar IRAS 16547$-$4247
• High Resolution $\lambda$=1mm CARMA Observations of Large Molecules in Orion-KL
• SMA Observations of W3(OH) Complex: Physical and Chemical Differentiation between W3(H${}_2$O) and W3(OH)

Cited by in corpus (5)

• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C${}_2$H${}_5$CN, CH${}_3$OCHO and CH${}_3$OH lines
• Mapping Observations of complex organic molecules around Sagittarius B2 with ARO 12m telescope
• Low-temperature chemistry induced by cosmic rays: positive and negative ions desorption from nitrile-bearing astrophysical ice analogues
• Organic Acid Chemistry in ISM: Detection of Formic Acid and its Prebiotic Chemistry in Hot Core G358.93$-$0.03 MM1
• Sub-arcsecond Imaging of the Complex Organic Chemistry in Massive Star-forming Region G10.6-0.4