SIMBAD references

Thermochemical equilibrium and kinetic calculations for the trace gases CO, PH₃, and SiH₄give three independent constraints on the water and total oxygen abundances of Saturn's deep atmosphere. A lower limit to the water abundance of H₂O/H₂≥(1.7^+0.7_–0.4)x10^–3 is given by CO chemistry, whereas an upper limit of H₂O/H₂≤(5.5^+0.8_–2.5)x10^–3 is given by PH₃chemistry. A combination of the CO and PH₃constraints indicates a water enrichment on Saturn of 1.9-6.1 times the solar system abundance (H₂O/H₂=8.96x10^–4). The total oxygen abundance must be at least 1.7 times the solar system abundance (O/H₂=1.16x10^–3) in order for SiH₄to remain below the detection limit of SiH₄/H₂<2x10^–10. A combination of the CO, PH₃, and SiH₄constraints suggests that the total oxygen abundance on Saturn is 3.2-6.4 times the solar system abundance. Our results indicate that oxygen on Saturn is less enriched than other heavy elements (such as C and P) relative to the solar system composition.