Geochimica et Cosmochimica Acta, 1999
Condensation in Dust-enriched Systems, by D.S. Ebel and L. Grossman,
Geochimica et Cosmochimica Acta, 1999
The nature of the condensates from dust-enriched bulk compositions is strongly influenced by the composition assumed for the dust, and an infinite variety of fractionated dust compositions can be imagined. One constraint on dust composition, however, is that it lead to condensate assemblages containing chondritic proportions of condensable elements. C1 chondrites are representative of the bulk composition of the condensable fraction of solar system matter. If the bulk of the condensable elements was originally brought to the solar nebula in the form of interstellar dust, then it is reasonable to assume that the aggregate composition of that dust had a bulk chemical composition similar to that of C1 chondrites. Table 1 shows the relative atomic abundances of the 23 elements considered in this work in solar gas (Anders and Grevesse, 1989), the C1 chondrite dust component of solar gas, and several dust-enriched systems. For a dust enrichment of n, one way to calculate the bulk composition is by adding (n-1) units of the C1 dust to solar composition. Enrichment factors of up to 1000 were investigated. Although there are as yet no astronomical observations that confirm, or astrophysical models that produce, such enrichments, there exists no evidence to rule out such enrichments in protoplanetary environments.
Table 1. Relative atomic abundances in solar composition and the C1 component of solar composition, both normalized to 10
6 atoms Si, and compositions of systems enriched in dust of C1 composition relative to solar.| Table 1. Relative atomic abundances in solar composition and the C1 component of solar composition, both normalized to 106 atoms Si, and compositions of systems enriched in dust of C1 composition relative to solar. | |||||
|
Solar |
Cl Dust |
100 x Cl |
500 x Cl |
1000 x Cl |
|
|---|---|---|---|---|---|
|
H |
2.79 x 10 10 |
5.28 x 10 6 |
2.84 x 10 10 |
3.05 x 10 10 |
3.32 x 10 10 |
|
He |
2.72 x 10 9 |
2.72 x 10 9 |
2.72 x 10 9 |
2.72 x 10 9 |
|
|
C |
1.01 x 10 7 |
7.56 x 10 5 |
8.50 x 10 7 |
3.87 x 10 8 |
7.65 x 10 8 |
|
N |
3.13 x 10 6 |
5.98 x 10 4 |
9.05 x 10 6 |
3.30 x 10 7 |
6.28 x 10 7 |
|
O |
2.38 x 10 7 |
7.63 x 10 6 |
7.80 x 10 8 |
3.83 x 10 9 |
7.65 x 10 9 |
|
F |
8.43 x 10 2 |
8.43 x 10 2 |
8.43 x 10 4 |
4.22 x 10 5 |
8.43 x 10 5 |
|
Ne |
3.44 x 10 6 |
3.44 x 10 6 |
3.44 x 10 6 |
3.44 x 10 6 |
|
|
Na |
5.74 x 10 4 |
5.74 x 10 4 |
5.74 x 10 6 |
2.87 x 10 7 |
5.74 x 10 7 |
|
Mg |
1.07 x 10 6 |
1.07 x 10 6 |
1.07 x 10 8 |
5.37 x 10 8 |
1.07 x 10 9 |
|
Al |
8.49 x 10 4 |
8.49 x 10 4 |
8.49 x 10 6 |
4.25 x 10 7 |
8.49 x 10 7 |
|
Si |
1.00 x 10 6 |
1.00 x 10 6 |
1.00 x 10 8 |
5.00 x 10 8 |
1.00 x 10 9 |
|
P |
1.04 x 10 4 |
1.04 x 10 4 |
1.04 x 10 6 |
5.20 x 10 6 |
1.04 x 10 7 |
|
S |
5.15 x 10 5 |
5.15 x 10 5 |
5.15 x 10 7 |
2.58 x 10 8 |
5.15 x 10 8 |
|
Cl |
5.24 x 10 3 |
5.24 x 10 3 |
5.24 x 10 5 |
2.62 x 10 6 |
5.24 x 10 6 |
|
Ar |
1.01 x 10 5 |
1.01 x 10 5 |
1.01 x 10 5 |
1.01 x 10 5 |
|
|
K |
3.77 x 10 3 |
3.77 x 10 3 |
3.77 x 10 5 |
1.89 x 10 6 |
3.77 x 10 6 |
|
Ca |
6.11 x 10 4 |
6.11 x 10 4 |
6.11 x 10 6 |
3.06 x 10 7 |
6.11 x 10 7 |
|
Ti |
2.40 x 10 3 |
2.40 x 10 3 |
2.40 x 10 5 |
1.20 x 10 6 |
2.40 x 10 6 |
|
Cr |
1.35 x 10 4 |
1.35 x 10 4 |
1.35 x 10 6 |
6.75 x 10 6 |
1.35 x 10 7 |
|
Mn |
9.55 x 10 3 |
9.55 x 10 3 |
9.55 x 10 5 |
4.78 x 10 6 |
9.55 x 10 6 |
|
Fe |
9.00 x 10 5 |
9.00 x 10 5 |
9.00 x 10 7 |
4.50 x 10 8 |
9.00 x 10 8 |
|
Co |
2.25 x 10 3 |
2.25 x 10 3 |
2.25 x 10 5 |
1.13 x 10 6 |
2.25 x 10 6 |
|
Ni |
4.93 x 10 4 |
4.93 x 10 4 |
4.93 x 10 6 |
2.47 x 10 7 |
4.93 x 10 7 |