|
Description
We present a study of the composition of gas and dust in the Large and Small Magellanic Clouds (LMC and SMC) using UV absorption spectroscopy. We measure PII and FeII along 84 spatially distributed sightlines toward the MCs using archival Far Ultraviolet Spectroscopic Explorer observations. For 16 of those sightlines, we also measure SiII, CrII, and ZnII from new Hubble Space Telescope Cosmic Origins Spectrograph observations. We analyze these spectra using a new spectral line analysis technique based on a semi-parametric Voigt profile model. We have combined these measurements with HI and H_2_ column densities and reference stellar abundances from the literature to derive gas-phase abundances, depletions, and gas-to-dust ratios (GDRs). Of our 84 P and 16 Zn measurements, 80 and 13, respectively, are depleted by more than 0.1dex, suggesting that P and Zn abundances are not accurate metallicity indicators at and above the metallicity of the SMC. Si, Cr, and Fe are systematically less depleted in the SMC than in the Milky Way (MW) or LMC. The minimum Si depletion in the SMC is consistent with zero. We find GDR ranges of 190-565 in the LMC and 480-2100 in the SMC, which is broadly consistent with GDRs from the literature. These ranges represent actual location to location variation and are evidence of dust destruction and/or growth in the diffuse neutral phase of the interstellar medium. Where they overlap in metallicity, the gas-phase abundances of the MW, LMC, and SMC and damped Ly{alpha} systems evolve similarly with metallicity.
|
