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Table 5

Chemical models considered for the IRAS 4A protostellar envelope

Model Pre-collapse Protostellar O2 formation rate Tpeak(O2)a Tpeak(NO)a
stage [yr] stage [yr] [cm3 s-1] [K] [K]
A 5 × 104 105 7.5 × 10-11 × (T/300)-0.25 0.119 ...
B 1 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.102 ...
C 2 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.085 ...
D 3 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.073 ...
E 5 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.042 ...
F 6 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.024 ...
GO 7 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.011 ...
GLb 7 × 105 105 7.84 × 10-12 0.0019 ...
HOb 8 × 105 105 7.5 × 10-11 × (T/300)-0.25 0.0046 0.015
HCb 8 × 105 105 3.50  × 10-11 0.0025 ...
HLb 8 × 105 105 7.84  × 10-12 0.0010 ...
IOb 1 × 106 105 7.5  × 10-11 × (T/300)-0.25 0.0033 0.011
ICb 1 × 106 105 3.50  × 10-11 0.0014 ...
ILb 1 × 106 105 7.84  × 10-12 0.0005 ...
J 8 × 104 2 × 104 3.50  × 10-11 0.106 ...
L 3 × 105 105 3.50 × 10-11 0.063 ...
M 3 × 105 105 7.84 × 10-12 0.047 ...
N 3 × 105 105 5.40 × 10-13 0.018 ...
O 5 × 105 105 3.50 × 10-11 0.031 ...
P 5 × 105 105 7.84 × 10-12 0.020 ...
Q 5 × 105 105 5.40 × 10-13 0.0068 0.091

Notes. Models G, H, and I use different rate coefficients for O2 formation (Eq. (1)), as indicated by subscripts: O for OSU, C for Carty et al. (2006), and L for Lin et al. (2008).

(a)

Ratran model results using a line width of 1.0 km s-1.

(b)

Best fit models. For NO, Case 2 is tabulated.

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