Gas phase Elemental abundances in Molecular cloudS (GEMS) I. The prototypical dark cloud TMC 1
Artikel i vetenskaplig tidskrift, 2019
GEMS is an IRAM 30 m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud Taurus molecular cloud (TMC) 1. Extensive millimeter observations have been carried out with the IRAM 30 m telescope (3 and 2mm) and the 40 m Yebes telescope (1.3 cm and 7 mm) to determine the fractional abundances of CO, HCO+, HCN, CS, SO, HCS+, and N2H+ in three cuts which intersect the dense filament at the well-known positions TMC 1-CP, TMC 1-NH3, and TMC 1-C, covering a visual extinction range from A(v) similar to 3 to similar to 20 mag. Two phases with differentiated chemistry can be distinguished: (i) the translucent envelope with molecular hydrogen densities of 1-5 x 10(3) cm(-3); and (ii) the dense phase, located at A(v) > 10 mag, with molecular hydrogen densities >10(4) cm(-3). Observations and modeling show that the gas phase abundances of C and O progressively decrease along the C+/C/CO transition zone (A(v) similar to 3 mag) where C/H similar to 8 x 10(-5) and C/O similar to 0.8-1, until the beginning of the dense phase at A(v) similar to 10 mag. This is consistent with the grain temperatures being below the CO evaporation temperature in this region. In the case of sulfur, a strong depletion should occur before the translucent phase where we estimate an S/H similar to (0.4-2.2) x 10(-6), an abundance similar to 7-40 times lower than the solar value. A second strong depletion must be present during the formation of the thick icy mantles to achieve the values of S/H measured in the dense cold cores (S/H similar to 8 x 10(-8)). Based on our chemical modeling, we constrain the value of zeta(H2) to similar to(0.5-1.8) x 10(-16) s(-1) in the translucent cloud.
ISM: abundances
ISM: kinematics and dynamics
stars: formation
ISM: molecules
astrochemistry
stars: low-mass
Författare
A. Fuente
Observatorio Astronómico Nacional (OAN)
D. G. Navarro
Observatorio Astronómico Nacional (OAN)
P. Caselli
Max-Planck-Gesellschaft
M. Gerin
Observatoire de Paris
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
E. Roueff
Université de recherche Paris Sciences et Lettres
T. Alonso-Albi
Observatorio Astronómico Nacional (OAN)
R. Bachiller
Observatorio Astronómico Nacional (OAN)
S. Cazaux
Universiteit Leiden
TU Delft
B. Commercon
Université de Lyon
R. Friesen
National Radio Astronomy Observatory
S. Garcia-Burillo
Observatorio Astronómico Nacional (OAN)
B. M. Giuliano
Max-Planck-Gesellschaft
J. R. Goicoechea
Consejo Superior de Investigaciones Científicas (CSIC)
P. Gratier
Université de Bordeaux
A. Hacar
Universiteit Leiden
I Jimenez-Serra
Centro de Astrobiología (INTA-CSIC)
J. Kirk
The University of Warwick
V Lattanzi
Max-Planck-Gesellschaft
J. C. Loison
Université de Bordeaux
J. Malinen
Helsingin Yliopisto
Universität zu Köln
N. Marcelino
Consejo Superior de Investigaciones Científicas (CSIC)
R. Martin-Domenech
Harvard-Smithsonian Center for Astrophysics
G. Munoz-Caro
Centro de Astrobiología (INTA-CSIC)
J. Pineda
Max-Planck-Gesellschaft
M. Tafalla
Observatorio Astronómico Nacional (OAN)
B. Tercero
Observatorio Astronómico Nacional (OAN)
D. Ward-Thompson
University of Central Lancashire
Sandra Treviño Morales
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
P. Riviere-Marichalar
Observatorio Astronómico Nacional (OAN)
O. Roncero
Consejo Superior de Investigaciones Científicas (CSIC)
T. Vidal
Université de Bordeaux
M. Y. Ballester
Universidade Federal de Juiz de Fora
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 624 A105PROMISE Origins of the Molecular Cloud Structure
Europeiska kommissionen (EU) (EC/H2020/639459), 2016-01-01 -- 2021-01-31.
Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
Geokemi
DOI
10.1051/0004-6361/201834654