The chemical structure of young high-mass star-forming clumps: (II) parsec-scale CO depletion and deuterium fraction of $rm HCO^+$. (arXiv:2008.03531v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Feng_S/0/1/0/all/0/1">S. Feng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_D/0/1/0/all/0/1">D. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Caselli_P/0/1/0/all/0/1">P. Caselli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Du_F/0/1/0/all/0/1">F. Du</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lin_Y/0/1/0/all/0/1">Y. Lin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sipila_O/0/1/0/all/0/1">O. Sipilä</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beuther_H/0/1/0/all/0/1">H. Beuther</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sanhueza_P/0/1/0/all/0/1">Patricio Sanhueza</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tatematsu_K/0/1/0/all/0/1">K. Tatematsu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_S/0/1/0/all/0/1">S. Y. Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Q/0/1/0/all/0/1">Q. Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Y/0/1/0/all/0/1">Y. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hogge_T/0/1/0/all/0/1">T. Hogge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jimenez_Serra_I/0/1/0/all/0/1">I. Jimenez-Serra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lu_X/0/1/0/all/0/1">X. Lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_T/0/1/0/all/0/1">T. Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_K/0/1/0/all/0/1">K. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Z/0/1/0/all/0/1">Z. Y. Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zahorecz_S/0/1/0/all/0/1">S. Zahorecz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_G/0/1/0/all/0/1">G. Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_H/0/1/0/all/0/1">H. B. Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_J/0/1/0/all/0/1">J. Yuan</a>
The physical and chemical properties of cold and dense molecular clouds are
key to understanding how stars form. Using the IRAM 30 m and NRO 45 m
telescopes, we carried out a Multiwavelength line-Imaging survey of the 70
$mu$m-dArk and bright clOuds (MIAO). At a linear resolution of 0.1–0.5 pc,
this work presents a detailed study of pc-scale CO depletion and $rm HCO^+$
deuterium (D-) fractionation toward four sources (G11.38+0.81, G15.21-0.43,
G14.49-0.13, and G34.74-0.12) included in our full sample. In each source with
$rm T<20$ K and $n_{rm H}rmsim10^4$–$rm 10^5,cm^{-3}$, we compared pairs
of neighboring 70 $mu$m bright and dark clumps and find that: (1) The $rm
H_2$ column density and dust temperature of each source show strong spatial
anti-correlation; (2) The spatial distribution of CO isotopologue lines and
dense gas tracers such as 1–0 lines of $rm H^{13}CO^+$ and $rm DCO^+$ are
anti-correlated; (3) The abundance ratio between $rm C^{18}O$ and $rm DCO^+$
shows a strong correlation with the source temperature; (4) Both the $rm
C^{18}O$ depletion factor and D-fraction of $rm HCO^+$ show robust decrease
from younger clumps to more evolved clumps by a factor of more than 3; (5)
Preliminary chemical modeling indicates chemical ages of our sources are
${sim}8times10^4$ yr, which is comparable to their free-fall timescales and
smaller than their contraction timescales, indicating that our sources are
likely {dynamically and chemically young.
The physical and chemical properties of cold and dense molecular clouds are
key to understanding how stars form. Using the IRAM 30 m and NRO 45 m
telescopes, we carried out a Multiwavelength line-Imaging survey of the 70
$mu$m-dArk and bright clOuds (MIAO). At a linear resolution of 0.1–0.5 pc,
this work presents a detailed study of pc-scale CO depletion and $rm HCO^+$
deuterium (D-) fractionation toward four sources (G11.38+0.81, G15.21-0.43,
G14.49-0.13, and G34.74-0.12) included in our full sample. In each source with
$rm T<20$ K and $n_{rm H}rmsim10^4$–$rm 10^5,cm^{-3}$, we compared pairs
of neighboring 70 $mu$m bright and dark clumps and find that: (1) The $rm
H_2$ column density and dust temperature of each source show strong spatial
anti-correlation; (2) The spatial distribution of CO isotopologue lines and
dense gas tracers such as 1–0 lines of $rm H^{13}CO^+$ and $rm DCO^+$ are
anti-correlated; (3) The abundance ratio between $rm C^{18}O$ and $rm DCO^+$
shows a strong correlation with the source temperature; (4) Both the $rm
C^{18}O$ depletion factor and D-fraction of $rm HCO^+$ show robust decrease
from younger clumps to more evolved clumps by a factor of more than 3; (5)
Preliminary chemical modeling indicates chemical ages of our sources are
${sim}8times10^4$ yr, which is comparable to their free-fall timescales and
smaller than their contraction timescales, indicating that our sources are
likely {dynamically and chemically young.
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