Interstellar Gas-phase Element Depletions in the Small Magellanic Cloud:
  A Guide to Correcting for Dust in QSO Absorption Line Systems
  We present data on the gas phase abundances for 9 different elements in the
interstellar medium of the Small Magellanic Cloud (SMC), based on the strengths
of ultraviolet absorption features over relevant velocities in the spectra of
18 stars within the SMC. From this information and the total abundances defined
by the element fractions in young stars in the SMC, we construct a general
interpretation on how these elements condense into solid form onto dust grains.
As a group, the elements Si, S, Cr, Fe, Ni, and Zn exhibit depletion sequences
similar to those in the local part of our Galaxy defined by Jenkins (2009). The
elements Mg and Ti deplete less rapidly in the SMC than in the Milky Way, and
Mn depletes more rapidly. We speculate that these differences might be
explained by the different chemical affinities to different existing grain
substrates. For instance, there is evidence that the mass fractions of
polycyclic aromatic hydrocarbons (PAHs) in the SMC are significantly lower than
those in the Milky Way. We propose that the depletion sequences that we
observed for the SMC may provide a better model for interpreting the element
abundances in low metallicity Damped Lyman Alpha (DLA) and sub-DLA absorption
systems that are recorded in the spectra of distant quasars and gamma ray burst
afterglows.
