Three dimensional projection effects on chemistry in a Planck galactic cold clump. (arXiv:1909.06004v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ge_J/0/1/0/all/0/1">J. X. Ge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mardones_D/0/1/0/all/0/1">Diego Mardones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+He_J/0/1/0/all/0/1">J. H. He</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rawlings_J/0/1/0/all/0/1">Jonathan M C Rawlings</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_S/0/1/0/all/0/1">Sheng-Yuan Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_J/0/1/0/all/0/1">Jeong-Eun Lee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tatematsu_K/0/1/0/all/0/1">Ken&#x27;ichi Tatematsu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_T/0/1/0/all/0/1">Tie Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_L/0/1/0/all/0/1">Lei Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chang_Q/0/1/0/all/0/1">Qiang Chang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Inostroza_N/0/1/0/all/0/1">Natalia Inostroza</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feng_S/0/1/0/all/0/1">S. Feng</a>

Offsets of molecular line emission peaks from continuum peaks are very common
but frequently difficult to explain with a single spherical cloud chemical
model. We propose that the spatial projection effects of an irregular three
dimensional (3D) cloud structure can be a solution. This work shows that the
idea can be successfully applied to the Planck cold clump G224.4-0.6 by
approximating it with four individual cloud cores whose chemical patterns
overlap with each other to produce observable line maps. With the empirical
physical structures inferred from the observation data of this clump and a
gas-grain chemical model, the four cores can satisfactorily reproduce its 850
$mu$m continuum map and the diverse peak offsets of CCS, HC$_3$N and
N$_2$H$^+$ simultaneously at a reasonable age of about $3times 10^6$ yrs. The
3D projection effects on chemistry has the potential to explain such
asymmetrical distributions of chemicals in many other molecular clouds.

Offsets of molecular line emission peaks from continuum peaks are very common
but frequently difficult to explain with a single spherical cloud chemical
model. We propose that the spatial projection effects of an irregular three
dimensional (3D) cloud structure can be a solution. This work shows that the
idea can be successfully applied to the Planck cold clump G224.4-0.6 by
approximating it with four individual cloud cores whose chemical patterns
overlap with each other to produce observable line maps. With the empirical
physical structures inferred from the observation data of this clump and a
gas-grain chemical model, the four cores can satisfactorily reproduce its 850
$mu$m continuum map and the diverse peak offsets of CCS, HC$_3$N and
N$_2$H$^+$ simultaneously at a reasonable age of about $3times 10^6$ yrs. The
3D projection effects on chemistry has the potential to explain such
asymmetrical distributions of chemicals in many other molecular clouds.

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