Ultraviolet absorption by interstellar gas near 30 Doradus

Journal Article · Sat Mar 15 04:00:00 EST 1980 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/157802· OSTI ID:5364247

de Boer, K S; Koornneef, J; Savage, B D

The International Ultraviolet Explorer was used to obtain high-resolution (lambda/..delta..lambdaapprox.1.2 x 10/sup 4/), far-UV spectra (lambdalambdaapprox.1150--2070 A) of two stars in the 30 Doradus H II region in the large Magellanic Cloud. In these spectra we can distinguish interstellar absorption components at heliocentric velocities of +20, +220, +250, and +290 km s/sup -1/. The +20 km s/sup -1/ component is produced by matter in our Galaxy. The high-velocity components are produced by absorbing gas in or near the LMC. The species detected include: H I, C I, C I*, C II, C II*, C IV, N I, O I, O I*, Mg I, Mg II, Al II, Al III, Si II, Si II*, Si IV, S II, Cr II, Fe II, Ni II, and Zn II. From the velocity pattern of the observed LMC features, a model for the line-of-signt distribution of the absorbing clouds is developed. From L..cap alpha.. we infer a gas-to-dust ratio for material in the 30 Dor region four times larger than the average galactic value. In the 290 km s/sup -1/ cloud, gaseous Si and O have abundances similar to those found in galactic interstellar gas, in agreement with results from emission-line studies of 30 Dor. The lines of Si IV and C IV seen at radial velocities as small as 180 km s/sup -1/ could indicate a halo of ionized gas around the LMC, similar to the galactic corona discovered from the same spectra by Savage and de Boer.

• Research Organization: Washburn Observatory, University of Wisconsin-Madison
• OSTI ID: 5364247
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 236:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION SPECTRA
ABUNDANCE
CHEMICAL COMPOSITION
COSMIC GASES
COSMIC RADIO SOURCES
FLUIDS
FUNCTIONS
GALAXIES
GASES
H1 REGIONS
INTERSTELLAR SPACE
LYMAN LINES
MAGELLANIC CLOUDS
MAIN SEQUENCE STARS
NEBULAE
RADIAL VELOCITY
SPACE
SPECTRA
SPECTRAL FUNCTIONS
STARS
ULTRAVIOLET SPECTRA
VELOCITY
WOLF-RAYET STARS