ALMA OBSERVATIONS OF THE IRDC CLUMP G34.43+00.24 MM3: DNC/HNC RATIO

作者：Sakai Takeshi^*; Sakai Nami; Furuya Kenji; Aikawa Yuri; Hirota Tomoya; Foster Jonathan B; Sanhueza Patricio; Jackson James M; Yamamoto Satoshi

来源：Astrophysical Journal, 2015, 803(2): 70.

DOI：10.1088/0004-637X/803/2/70

• ISM: clouds
• ISM: molecules
• stars: formation

We have observed the clump G34.43+00.24 MM3 associated with an infrared dark cloud in DNC J = 3-2, (HNC)-C-13 J = 3-2, and N2H+ J = 3-2 with the Atacama Large Millimeter/submillimeter Array (ALMA). The N2H+ emission is found to be relatively weak near the hot core and the outflows, and its distribution is clearly anti-correlated with the CS emission. This result indicates that a young outflow is interacting with cold ambient gas. The (HNC)-C-13 emission is compact and mostly emanates from the hot core, whereas the DNC emission is extended around the hot core. Thus, the DNC and (HNC)-C-13 emission traces warm regions near the protostar differently. The DNC emission is stronger than the (HNC)-C-13 emission toward most parts of this clump. The DNC/HNC abundance ratio averaged within a 15 '' x15 '' area around the phase center is higher than 0.06. This ratio is much higher than the value obtained by the previous single-dish observations of DNC and (HNC)-C-13 J = 1-0 (similar to 0.003). It seems likely that the DNC and HNC emission observed with the single-dish telescope traces lower density envelopes, while that observed with ALMA traces higher density and highly deuterated regions. We have compared the observational results with chemical-model results in order to investigate the behavior of DNC and HNC in the dense cores. Taking these results into account, we suggest that the low DNC/HNC ratio in the high-mass sources obtained by the single-dish observations are at least partly due to the low filling factor of the high density regions.

• 出版日期2015-4-20
• 单位中国科学院国家天文台