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Table 4

Element abundances in LB 1919 and GD 246 as determined from UV spectra with homogeneous models with 56 000 ± 2000 K and log g = 7.9 ± 0.3 for LB 1919 and 57 000 ± 2000 K and log g = 7.6 ± 0.3 for GD 246.

WD Element Abundance (X/H) Uncertainty Ions Diff. Literature
LB 1919 C  <1.0 × 10-7 5.0 × 10-8 C iii  > 
O  <1.0 × 10-6 2.0 × 10-6 O vi  > 
Si  <5.0 × 10-9 5.0 × 10-9 Si iii+iv  > 
P  <1.0 × 10-10 1.5 × 10-10 P v  > 
S  <1.75 × 10-8 7.5 × 10-9 S iv+vi  > 
Fe  <1.0 × 10-6 1.0 × 10-6 Fe v  > 
Ni  <1.0 × 10-6 1.0 × 10-6 Ni v  > 
GD 246 C  <3.2 × 10-8 1.5 × 10-8 C iii  > 
O  <6.0 × 10-8 5.0 × 10-8 O vi  >  1.6 × 10-7a
Si 1.2 × 10-7 2.0 × 10-8 Si iv  =  5.0 × 10-8b
3.2 × 10-8c
1.2 × 10-7a
P 3.0 × 10-9 2.0 × 10-9 P v  >  6.3 × 10-9c
7.5 × 10-9b
S 5.0 × 10-9 2.0 × 10-9 S vi  >   <3.0 × 10-7b
Ge 5.0 × 10-9 1.0 × 10-9 Ge iv  <  2.5 × 10-9d
Fe  < 1.0 × 10-6 1.0 × 10-6 Fe v  >   <2.0 × 10-5b
 >   <1.2 × 10-7a
Ni  < 1.0 × 10-6 1.0 × 10-6 Ni v  >   <1.3 × 10-7a

Notes. Identified ions are noted in the fifth column. Column six indicates the tendency of the abundance of a diffusion model to be stronger (>) or weaker (<) than the observed line strength. Literature values for the abundances are given in the last column.

References. 

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