Gas phase Elemental abundances in Molecular cloudS (GEMS): IV. Observational results and statistical trends
Artikel i vetenskaplig tidskrift, 2021
Gas phase Elemental abundances in Molecular CloudS (GEMS) is an IRAM 30 m Large Program designed to provide estimates of the S, C, N, and O depletions and gas ionization degree, X(e-), in a selected set of star-forming filaments of Taurus, Perseus, and Orion. Our immediate goal is to build up a complete and large database of molecular abundances that can serve as an observational basis for estimating X(e-) and the C, O, N, and S depletions through chemical modeling. We observed and derived the abundances of 14 species (13CO, C18O, HCO+, H13CO+, HC18O+, HCN, H13CN, HNC, HCS+, CS, SO, 34SO, H2S, and OCS) in 244 positions, covering the AV ~3 to ~100 mag, n(H2) ~ a few 103 to 106 cm-3, and Tk ~10 to ~30 K ranges in these clouds, and avoiding protostars, HII regions, and bipolar outflows. A statistical analysis is carried out in order to identify general trends between different species and with physical parameters. Relations between molecules reveal strong linear correlations which define three different families of species: (1) 13CO and C18O isotopologs; (2) H13CO+, HC18O+, H13 CN, and HNC; and (3) the S-bearing molecules. The abundances of the CO isotopologs increase with the gas kinetic temperature until TK ~ 15 K. For higher temperatures, the abundance remains constant with a scatter of a factor of ~3. The abundances of H13 CO+, HC18 O+, H13 CN, and HNC are well correlated with each other, and all of them decrease with molecular hydrogen density, following the law ∝ n(H2)-0.8 ± 0.2. The abundances of S-bearing species also decrease with molecular hydrogen density at a rate of (S-bearing/H)gas ∝ n(H2)-0.6 ± 0.1. The abundances of molecules belonging to groups 2 and 3 do not present any clear trend with gas temperature. At scales of molecular clouds, the C18O abundance is the quantity that better correlates with the cloud mass. We discuss the utility of the 13CO/C18O, HCO+/H13CO+, and H13 CO+/H13CN abundance ratios as chemical diagnostics of star formation in external galaxies.
Galaxies: ISM
ISM: clouds
Stars: formation
ISM: molecules
Astrochemistry
ISM: abundances
Författare
M. Rodríguez-Baras
Observatorio Astronómico Nacional (OAN)
A. Fuente
Observatorio Astronómico Nacional (OAN)
P. Riviere-Marichalar
Observatorio Astronómico Nacional (OAN)
D. Navarro-Almaida
Observatorio Astronómico Nacional (OAN)
P. Caselli
Max-Planck-Gesellschaft
M. Gerin
Observatoire de Paris
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
Evelyne Roueff
Observatoire de Paris
V. Wakelam
Université de Bordeaux
G. Esplugues
Observatorio Astronómico Nacional (OAN)
S. G. Burillo
Observatorio Astronómico Nacional (OAN)
R. Le Gal
Harvard-Smithsonian Center for Astrophysics
S. Spezzano
Max-Planck-Gesellschaft
T. Alonso-Albi
Observatorio Astronómico Nacional (OAN)
R. Bachiller
Observatorio Astronómico Nacional (OAN)
S. Cazaux
Universiteit Leiden
TU Delft
B. Commerçon
École Normale Supérieure de Lyon
J.R. Goicoechea
CSIC - Instituto de Fisica Fundamental (IFF)
J. C. Loison
Université de Bordeaux
Sandra Treviño Morales
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
O. Roncero
CSIC - Instituto de Fisica Fundamental (IFF)
I. Jimenez-Serra
Centro de Astrobiologia (CAB)
J. C. Laas
Max-Planck-Gesellschaft
A. Hacar
Universität Wien
J. Kirk
University of Central Lancashire
V. Lattanzi
Max-Planck-Gesellschaft
R. Martín-Doménech
Harvard-Smithsonian Center for Astrophysics
G. Muñoz-Caro
Centro de Astrobiologia (CAB)
J. E. Pineda
Max-Planck-Gesellschaft
B. Tercero
Observatorio de Yebes (IGN)
Observatorio Astronómico Nacional (OAN)
D. Ward-Thompson
University of Central Lancashire
M. Tafalla
Observatorio Astronómico Nacional (OAN)
N. Marcelino
CSIC - Instituto de Fisica Fundamental (IFF)
J. Malinen
Universität zu Köln
Helsingin Yliopisto
R. Friesen
National Radio Astronomy Observatory
B. M. Giuliano
Max-Planck-Gesellschaft
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 648 A120Ämneskategorier
Fysikalisk kemi
Astronomi, astrofysik och kosmologi
Ekologi
DOI
10.1051/0004-6361/202040112