J/ApJ/822/105 Chemical evolution in the SMC (Acharyya+, 2016)
Simulations of the chemistry in the Small Magellanic Cloud.
AcharyyaK., Herbst E.
<Astrophys. J., 822, 105-105 (2016)>
=2016ApJ...822..105A 2016ApJ...822..105A (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Models ; Magellanic Clouds ; Extinction
Keywords: astrochemistry; ISM: molecules; molecular processes
Abstract:
The Large (LMC) and Small (SMC) Magellanic Clouds are irregular
satellite galaxies of the Milky Way. Both are metal- and dust-poor,
although the SMC is significantly poorer in both. We have recently
simulated the chemistry in cold dense regions of the LMC and found
that a rich chemistry exists in the gas-phase. In this paper, we
report a companion study of the chemistry of dense regions of the SMC,
confining our attention to cold regions of dense clouds with a variety
of densities, visual extinctions, and grain temperatures, and a fixed
gas-phase temperature. With a gas-to-dust ratio and elemental
abundances based on observations and scaling, we found that for
molecules like CO and N2, which are predominantly formed in the gas
phase, their abundances are consistent with the reduced elemental
abundances of their constituent elements above 25K; however, for
species that are produced fully (e.g., CH3OH) or partially on the
grain surface (e.g., H2CO, NH3), the dependence on metallicity can
be complex. Most of the major gas-phase species observed in our Galaxy
are produced in the SMC although in lower quantities. With our
simulations, we are able to explain observed gas-phase abundances
reasonably well in the dense sources N27 and LIRS 36. We have also
compared our calculated abundances of selected ices with limited
observations in dense regions in front of young stellar objects.
Description:
For this work we used the same network as used in Acharyya et al.
(2015MolPh.113.2243A 2015MolPh.113.2243A) and Acharyya & Herbst (2015, J/ApJ/812/142). See
section 3 for further explanations.
Objects:
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RA (ICRS) DE Designation(s)
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00 52 38.0 -72 48 01 SMC = NAME SMC
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table7.dat 193 261 Abundances of assorted gas-phase species
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See also:
J/ApJ/812/142 : LMC chemical evolution with a new model (Acharyya+, 2015)
J/MNRAS/442/1680 : Red giants in SMC. Abundances (Dobbie+, 2014)
J/ApJ/744/20 : S4MC project: 6 star forming regions PAHs (Sandstrom+, 2012)
J/ApJ/678/985 : c2d Spitzer survey of interstellar ices. I. (Boogert+, 2008)
J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)
J/A+A/304/347 : 40 field red supergiants in the SMC (Meliani+, 1995)
J/A+A/276/25 : ESO-SEST Key Program on CO in LMC and SMC (Israel+ 1993)
Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 E3.0 cm-3 nH [10000/1000000] Hydrogen number density
5- 6 I2 mag Av [3/10] The V band extinction
8- 13 A6 --- Species Species identifier
15- 22 E8.2 --- A1e4-10 Calculated abundance at 1e4yr and 10K (1)
24- 31 E8.2 --- A1e4-20 Calculated abundance at 1e4yr and 20K (1)
33- 40 E8.2 --- A1e4-30 Calculated abundance at 1e4yr and 30K (1)
42- 49 E8.2 --- A1e4-40 Calculated abundance at 1e4yr and 40K (1)
51- 58 E8.2 --- A1e4-50 Calculated abundance at 1e4yr and 50K (1)
60- 67 E8.2 --- A5e4-10 Calculated abundance at 5e4yr and 10K (1)
69- 76 E8.2 --- A5e4-20 Calculated abundance at 5e4yr and 20K (1)
78- 85 E8.2 --- A5e4-30 Calculated abundance at 5e4yr and 30K (1)
87- 94 E8.2 --- A5e4-40 Calculated abundance at 5e4yr and 40K (1)
96-103 E8.2 --- A5e4-50 Calculated abundance at 5e4yr and 50K (1)
105-112 E8.2 --- A1e5-10 Calculated abundance at 1e5yr and 10K (1)
114-121 E8.2 --- A1e5-20 Calculated abundance at 1e5yr and 20K (1)
123-130 E8.2 --- A1e5-30 Calculated abundance at 1e5yr and 30K (1)
132-139 E8.2 --- A1e5-40 Calculated abundance at 1e5yr and 40K (1)
141-148 E8.2 --- A1e5-50 Calculated abundance at 1e5yr and 50K (1)
150-157 E8.2 --- A5e5-10 Calculated abundance at 5e5yr and 10K (1)
159-166 E8.2 --- A5e5-20 Calculated abundance at 5e5yr and 20K (1)
168-175 E8.2 --- A5e5-30 Calculated abundance at 5e5yr and 30K (1)
177-184 E8.2 --- A5e5-40 Calculated abundance at 5e5yr and 40K (1)
186-193 E8.2 --- A5e5-50 Calculated abundance at 5e5yr and 50K (1)
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Note (1): For all computed values in this table, the UV field and cosmic ray
ionization rate lie at their fiducial values: ξ=10
and ζ=1.3e-17/s.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Aug-2016