The Variation of Magnesium Depletion with Line of Sight Conditions

Abstract

In this paper we report on the gas-phase abundance of singly-ionized magnesium (Mg II) in 44 lines of sight, using data from the Hubble Space Telescope (HST). We measure Mg II column densities by analyzing medium- and high-resolution archival STIS spectra of the 1240 A doublet of Mg II. We find that Mg II depletion is correlated with many line of sight parameters (e.g. F(H_2), E_(B-V), E_(B-V)/r, A_V, and A_V/r) in addition to the well-known correlation with <n_H>. These parameters should be more directly related to dust content and thus have more physical significance with regard to the depletion of elements such as magnesium. We examine the significance of these additional correlations as compared to the known correlation between Mg II depletion and <n_H>. While none of the correlations are better predictors of Mg II depletion than <n_H>, some are statistically significant even assuming fixed <n_H>. We discuss the ranges over which these correlations are valid, their strength at fixed <n_H>, and physical interpretations.

Accepted for publication in ApJ, 669, 401. See ApJ version for small changes. 32 total pages (preprint format), 6 tables, 7 figures

References in corpus (8)

• New Interstellar Dust Models Consistent with Extinction, Emission, and Abundance Constraints
• The Homogeneity of Interstellar Oxygen in the Galactic Disk
• The Homogeneity of Interstellar Elemental Abundances in the Galactic Disk
• Oxygen Gas Phase Abundance Revisited
• Cloud Structure and Physical Conditions in Star-forming Regions from Optical Observations. I. Data and Component Structure
• The Abundance of Interstellar Fluorine and Its Implications
• New Insights on Interstellar Gas-Phase Iron
• Is There Enhanced Depletion of Gas-Phase Nitrogen in Moderately Reddened Lines of Sight?

Cited by in corpus (15)

• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• Discovery of a Perseus-like cloud in the early Universe: HI-to-H2 transition, carbon monoxide and small dust grains at zabs=2.53 towards the quasar J0000+0048
• From interstellar abundances to grain composition: the major dust constituents Mg, Si and Fe
• New Insights on Interstellar Gas-Phase Iron
• 3D chemical structure of diffuse turbulent ISM. I. Statistics of the HI-to-H${}_2$ transition
• The Behavior of Selected Diffuse Interstellar Bands with Molecular Fraction in Diffuse Atomic and Molecular Clouds
• Application of Relativistic Coupled-cluster Theory to Electron Impact Excitations of Mg${}^{+}$ in the Plasma Environment
• Interstellar Extinction and Elemental Abundances
• The Abundance of Boron in Diffuse Interstellar Clouds
• A High Precision Survey of the D/H Ratio in the Nearby Interstellar Medium
• A Closer Look at Some Gas-Phase Depletions in the ISM: Trends for O, Ge, and Kr vs. $F_{\ast }$, $f({\mathrm{H}}_2)$, and Starlight Intensity
• Interstellar Extinction and Elemental Abundances: Individual Sight Lines
• A Reexamination of Phosphorus and Chlorine Depletions in the Diffuse Interstellar Medium
• The Vertical Structure and Asymmetry of Mg ii-enriched Gas in the Milky Way Disk
• Families and Clusters of Diffuse Interstellar Bands: a Data-Driven Correlation Analysis