Table 6: Initial abundances. The total oxygen budget is allowed to vary to explore the effect of different C/O elemental ratios. Water is assumed to be absent at t=0.
Species n(species)/n(H)

H 1.0

He $7.1 \times 10^{-2}$

C $1.0 \times 10^{-4}$

N $2.0 \times 10^{-5}$

O $1.7 \times 10^{-4}$

C⁺ $4.0 \times 10^{-6}$

CO $8.5 \times 10^{-5}$

H₂O $1.0 \times 10^{-30}$

**Table 6:** Initial abundances. The total oxygen budget is allowed to vary to explore the effect of different C/O elemental ratios. Water is assumed to be absent at t=0.
Species	n(species)/n(H)
H	1.0
He	$7.1 \times 10^{-2}$
C	$1.0 \times 10^{-4}$
N	$2.0 \times 10^{-5}$
O	$1.7 \times 10^{-4}$
C⁺	$4.0 \times 10^{-6}$
CO	$8.5 \times 10^{-5}$
H₂O	$1.0 \times 10^{-30}$

Source LaTeX | All tables | In the text

	1 Introduction
	2 Observations
	3 Chemical modeling
	4 Results of the chemical model calculations and discussion
	5 Conclusion and future prospects
	References