ALMA observations of the IRDC clump G34.43+00.24 MM3: DNC/HNC ratio

Journal Article · Mon Apr 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/803/2/70· OSTI ID:22882557

Sakai, Takeshi ^[1]; Sakai, Nami; Yamamoto, Satoshi ^[2]; Furuya, Kenji ^[3]; Aikawa, Yuri ^[4]; Hirota, Tomoya; Sanhueza, Patricio ^[5]; Foster, Jonathan B. ^[6]; Jackson, James M. ^[7]

---

1. Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan)
2. Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033 (Japan)
3. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
4. Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan)
5. National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)
6. Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520 (United States)
7. Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States)

We have observed the clump G34.43+00.24 MM3 associated with an infrared dark cloud in DNC J = 3–2, HN{sup 13}C J = 3–2, and N{sub 2}H{sup +} J = 3–2 with the Atacama Large Millimeter/submillimeter Array (ALMA). The N{sub 2}H{sup +} 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 HN{sup 13}C emission is compact and mostly emanates from the hot core, whereas the DNC emission is extended around the hot core. Thus, the DNC and HN{sup 13}C emission traces warm regions near the protostar differently. The DNC emission is stronger than the HN{sup 13}C emission toward most parts of this clump. The DNC/HNC abundance ratio averaged within a 15{sup ′′} × 15{sup ′′} 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 HN{sup 13}C J = 1–0 (∼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.

• OSTI ID: 22882557
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 803; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
COSMIC GASES
DEUTERIUM COMPOUNDS
DISTRIBUTION
ELEMENT ABUNDANCE
EMISSION
HYDROGEN CYANIDES
INFRARED RADIATION
MASS
MOLECULES
NITROGEN 13
PROTOSTARS
STAR EVOLUTION
STARS
TELESCOPES