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J/A+A/321/293       SiO production in interstellar shocks    (Schilke+ 1997)

SiO production in interstellar shocks. Schilke P., Walmsley C.M., Pineau des Forets G., Flower D.R. <Astron. Astrophys. 321, 293 (1997)> =1997A&A...321..293S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Atomic physics Keywords: molecular processes - shock waves - ISM: abundances; jets and outflows; molecules Abstract: We study the production of SiO in the gas phase of molecular outflows, through the sputtering of Si-bearing material in grains. The sputtering is driven by neutral particle impact on charged grains in C-type shocks, at the speed corresponding to ambipolar diffusion. Shock speeds in the range 10<vs<40km/s and preshock densities 104<nH<107cm-3 have been investigated. Sputtering of Si-bearing material in both the cores and the mantles of the grains is considered. We find that, for vs of approximately 25km/s and nH of the order 105cm-3, column densities of SiO similar to those observed in molecular out flow regions can be generated by either mechanism. Impact by particles heavier than helium dominates the core-sputtering process for shock velocities of this order. The profiles of rotational transitions of SiO are computed and compared with observations of molecular outflows. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1a 72 30 *Mantle and dissociative sputtering parameters table1b 72 12 *Dissociation on impact parameters table2 80 100 Rate coefficient parameters, for gas-phase reactions involving Si-bearing species
Note to table1a and table1b: Parameters adopted when computing the rate coefficients for reactions involving grains Byte-by-byte Description of file: table1a
Bytes Format Units Label Explanations
1 A1 --- Type [ab] a: mantle sputtering, b: dissociative sputtering 3- 15 A13 --- R1 Beginning species of the reaction (1) 17- 37 A21 --- R2 Resulting species of the reaction 39- 45 E7.2 --- S Sputtering yield factor 48- 52 F5.2 eV Eth Sputtering threshold energy
Note (1): Asterisks denote species in grain mantles
Byte-by-byte Description of file: table1b
Bytes Format Units Label Explanations
1 A1 --- Type [c] c: dissociation on impact 3- 15 A13 --- R1 Beginning species of the reaction 17- 37 A21 --- R2 Resulting species of the reaction 39- 45 E7.2 --- Y0 Multiplicative constant (1) 48- 52 F5.2 --- Ediss Dissociation energy (1)
Note (1): The dissociative probability has an Arrhenius form, Y0exp(-Ediss/E), where E is the impact energy, Ediss the dissociation energy and Y0 the multiplicative constant
Byte-by-byte Description of file: table2
Bytes Format Units Label Explanations
1- 14 A14 --- R1 Beginning species of the reaction 16- 32 A17 --- R2 Resulting species of the reaction 34- 41 E8.2 --- gamma Gamma coefficient (1) 44- 48 F5.2 --- alpha ? Alpha coefficient (1) 50- 56 F7.1 K beta ? Beta coefficient (1) 58 I1 --- Note ? Note (2)
Note (1): Rate coefficient : gamma.(T/300)alpha.exp(-beta/T) cm3/s Note (2): 1: Langer & Glassgold, 1990, ApJ 352, 123 2: Supposed to be the same as CH (Gredel, 1990) 3: MacKay, 1995MNRAS.274..694M 4: UMIST ratefile (Millar et al., 1996, A&AS, in press) 5: Herbst (1995, private communication) 6: Elkin & Armentrout, 1984, J. Phys. Chem. 88, 5454 7: See the discussion of Flower et al., 1996MNRAS.280..447F
References: Gredel R., 1990 in "Molecular astrophysics", Hartquist T.W. ed, Cambridge University Press, Cambridge, p.305
(End) Patricia Bauer [CDS] 30-Sep-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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