UV absorption sight lines of LMC and SMC

DOI

We have determined column densities of H I and/or H_2_ for sight lines in the Magellanic Clouds from archival Hubble Space Telescope and Far-Ultraviolet Spectroscopic Explorer spectra of H I Ly{alpha} and H_2_Lyman-band absorption. Together with some similar data from the literature, we now have absorption-based N(H I) and/or N(H_2_) for 285 Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) sight lines (114 with a detection or limit for both species) - enabling more extensive, direct, and accurate determinations of molecular fractions, gas-to-dust ratios, and elemental depletions in these two nearby, low-metallicity galaxies. For sight lines where the N(H I) estimated from 21 cm emission is significantly higher than the value derived from Ly{alpha} absorption (presumably due to emission from gas beyond the target stars), integration of the 21 cm profile only over the velocity range seen in Na I or H_2_absorption generally yields much better agreement. Conversely, N(21 cm) can be lower than N(Ly{alpha}) by factors of 2-3 in some LMC sight lines - suggestive of small-scale structure within the 21 cm beam(s) and/or some saturation in the emission. The mean gas-to-dust ratios obtained from N(H_tot_)/E(B-V) are larger than in our Galaxy, by factors of 2.8-2.9 in the LMC and 4.1-5.2 in the SMC - i.e., factors similar to the differences in metallicity. The N(H_2_)/E(B-V) ratios are more similar in the three galaxies, but with considerable scatter within each galaxy. These data may be used to test models of the atomic-to-molecular transition at low metallicities and predictions of N(H_2_) based on comparisons of 21 cm emission and the IR emission from dust.

Cone search capability for table J/ApJ/745/173/slines (SMC and LMC sight lines })

Identifier
DOI http://doi.org/10.26093/cds/vizier.17450173
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJ/745/173
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/745/173
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/745/173
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/ApJ/745/173
Provenance
Creator Welty D.E.; Xue R.; Wong T.
Publisher CDS
Publication Year 2013
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Galactic and extragalactic Astronomy; Interstellar medium; Natural Sciences; Observational Astronomy; Physics