DEUTERIUM FRACTIONATION AS AN EVOLUTIONARY PROBE IN THE INFRARED DARK CLOUD G28.34+0.06
- Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)
- Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China)
We have observed the J = 3 - 2 transition of N{sub 2}H{sup +} and N{sub 2}D{sup +} to investigate the trend of deuterium fractionation with evolutionary stage in three selected regions in the infrared dark cloud (IRDC) G28.34+0.06 with the Submillimeter Telescope and the Submillimeter Array. A comprehensible enhancement of roughly 3 orders of magnitude in deuterium fractionation over the local interstellar D/H ratio is observed in all sources. In particular, our sample of massive star-forming cores in G28.34+0.06 shows a moderate decreasing trend over a factor of 3 in the N(N{sub 2}D{sup +})/N(N{sub 2}H{sup +}) ratio with evolutionary stage, a behavior resembling that previously found in low-mass protostellar cores. This suggests a possible extension for the use of the N(N{sub 2}D{sup +})/N(N{sub 2}H{sup +}) ratio as an evolutionary tracer to high-mass protostellar candidates. In the most evolved core, MM1, the N{sub 2}H{sup +}(3-2) emission appears to avoid the warm region traced by dust continuum emission and emission of {sup 13}CO sublimated from grain mantles, indicating an instant release of gas-phase CO. The majority of the N{sub 2}H{sup +} and N{sub 2}D{sup +} emission is associated with extended structures larger than 8'' ({approx}0.2 pc)
- OSTI ID:
- 21305049
- Journal Information:
- Astrophysical Journal Letters, Vol. 713, Issue 1; Other Information: DOI: 10.1088/2041-8205/713/1/L50; Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
FRAGMENTATION OF MOLECULAR CLUMPS AND FORMATION OF A PROTOCLUSTER
Cloud Structure of Three Galactic Infrared Dark Star-forming Regions from Combining Ground- and Space-based Bolometric Observations