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Home All issues Volume 497 / No 3 (April III 2009) A&A, 497 3 (2009) 773-787 Full HTML
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Table 2:

Grain mantle compositions.
Speciesa Elias 16b Elias 29c Class I/II Objectsd Model t = 0.0 t = 0.5 $t_{{\rm ff}}$ t = 1.5 $t_{{\rm ff}}$ t = 2.5 $t_{{\rm ff}}$ Midplane diske
H2Of 100 100 100 S 1.55(-4) 1.65(-4) 1.71(-4) 1.71(-4) 1.8(-4)
        G 1.24(-5) 8.29(-6) 4.5(-6) 4.2(-6) 1.4(-5)g
CO 25 5.6 ... S 13.9 17.0 11.6 5.0 17.6
        G 71.6 61.1 31.4 13.5 77.5
CO2 24 22 $\sim$12 S 46.9 40.6 31.0 29.8 37.7
        G 3.6(-1) 3.1(-1) 2.2(-1) 2.2(-1) 4.2(-1)
CH3OH <2.3 <4.4 $\ga $2-9 S 8.7 7.0 6.6 6.7 2.2
        G 1.4(-5) 2.1(-5) 2.9(-5) 2.9(-5) 7.0(-8)
NH3 $\leq $8 <9.2 $\la $14 S 9.8(-1) 3.3(-1) 2.6(-1) 3.4(-2) 4.0(-1)
        G 1.7(-2) 1.1(-2) 2.7(-3) 1.0(-3) 6.0(-3)
CH4 <3 <1.6 $\sim$4 S 1.1(-1) 1.7(-1) 1.4(-1) 1.0(-1) 1.8
        G 2.2 2.0 1.6 1.4 1.0
H2CO ... <1.8 $\sim$2 S 1.1 1.6 3.9 4.1 2.9
        G 4.5(-4) 3.7(-4) 4.3(-4) 4.7(-4) 4.8(-4)
OCS <0.2 <0.05 ... S 4.3(-9) 4.9(-10) 4.6(-10) 8.1(-10) 0
        G 3.7(-3) 4.0(-3) 3.0(-3) 2.7(-3) 9.1(-2)
HCOOH ... <0.9 $\sim$0.6 S 1.5 2.6(-2) 1.4(-2) 1.4(-2) 3.4(-2)
        G 7.7(-3) 9.3(-3) 7.7(-3) 7.1(-3) 6.9(-1)
SO2 ... ... $\sim$0.5 S 2.3(-2) 1.3(-2) 8.7(-3) 8.4(-3) 1.2(-2)
        G 7.8(-4) 1.0(-3) 7.0(-4) 5.9(-4) 8.3(-3)
Observed ice compositions as percentage of the H2O abundance compared with model results. Every first line for a species shows the results from Model S (includes surface reactions) and the second line shows the results for Model G (excludes surface reactions). a Abundances are given as $a(b) = a \times 10^{b}$. b CO Chiar et al. (1995); CO2, CH3OH, NH3, and CH4 Knez et al. (2005); OCS Palumbo et al. (1997). c Ehrenfreund & Schutte (2000) and Boogert & Ehrenfreund (2004). d Zasowski et al. (2007). e At t = 2.5 $t_{{\rm ff}}$ and a radius of $\sim$500 AU. f H2O fractional abundance are given for the simulation: $n({\rm H}_{2}{\rm O})/n({\rm H}_2)$. g For model G we have taken an H2O fractional abundance of $1.8 \times 10^{-4}$ for calculating the ice fraction of other species, instead of the reported values on this line.

Source LaTeX | All tables | In the text

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