@misc{10481/57332,
year = {2019},
url = {http://hdl.handle.net/10481/57332},
abstract = {We emphasize that the completeness of the partition function, that is, the use of a converged partition function at the typical temperature
range of the survey, is very important to decrease the uncertainty on this quantity and thus to derive reliable interstellar molecular
densities. In that context, we show how the use of different approximations for the rovibrational partition function together with
some interpolation and/or extrapolation procedures may affect the estimate of the interstellar molecular column density. For that
purpose, we apply the partition function calculations to astronomical observations performed with the IRAM-30m telescope towards
the NGC 7538–IRS1 source of two N-bearing molecules: isocyanic acid (HNCO, a quasilinear molecule) and methyl cyanide (CH3CN,
a symmetric top molecule). The case of methyl formate (HCOOCH3), which is an asymmetric top O-bearing molecule containing
an internal rotor is also discussed. Our analysis shows that the use of different partition function approximations leads to relative
differences in the resulting column densities in the range 9–43%. Thus, we expect this work to be relevant for surveys of sources with
temperatures higher than 300K and to observations in the infrared.},
organization = {This work is partly supported by CMST COST Action
CM1401 Our Astro-Chemical History and CMST COST Action CM1405
MOLIM. The work of C.F. is supported by the French National Research
Agency in the framework of the Investissements d’Avenir program (ANR-15-
IDEX-02), through the funding of the “Origin of Life” project of the Université
Grenoble-Alpes. C.C. and C.F. acknowledge funding from the European
Research Council (ERC) under the European Union’s Horizon 2020 research
and innovation programme, for the Project “The Dawn of Organic Chemistry”
(DOC), grant agreement No 741002. I.K. would like to thank the French
programme of Chimie Interstellaire PCMI. C.F. and D.F. acknowledge support
from the Italian Ministry of Education, Universities and Research, project
SIR (RBSI14ZRHR). E.A.B. acknowledges support from NSF (AST-1514670)
and NASA (NNX16AB48G). M.C. acknowledges the financial support from
FIS2014-53448-C2-2-P (MINECO, Spain), from the Centro de Estudios Avanzados
de Física, Matemáticas y Computación (CEAFMC) of the University of
Huelva and from the Consejería de Conocimiento, Investigación y Universidad,
Junta de Andalucía and European Regional Development Fund (ERDF), ref.
SOMM17/6105/UGR.},
publisher = {ASTRONOMY & ASTROPHYSICS},
keywords = {techniques},
keywords = {spectroscopic – ISM},
keywords = {abundances – radio lines},
keywords = {ISM},
title = {Impact of nonconvergence and various approximations of the partition function on the molecular column densities in the interstellar medium},
doi = {10.1051/0004-6361/201935469},
author = {Carvajal Rodríguez, Miguel Ángel and Favre, C. and Kleiner, I. and Ceccarelli, C. and Bergin, E. A. and Fedele, D.},
}