Jura, Michael A. | Engineering Papers

NASA NTRS1989

Interstellar matter in early-type galaxies. I - IRAS flux densities

The data from the IRAS satellite were coadded for about 1150 early-type galaxies with apparent magnitudes brighter than 14 mag. The sample selection, averaging procedure, and errors are discussed. Results are reported of galaxies of large angular size compared with the IRAS beamwidth and for a sample of dwarf ellipticals in the Virgo cluster. At 60 and 100 microns, about 45 percent of the ellipticals and 68 percent of the S0 galaxies are detected, showing that a large fraction of these galaxies contain cool interstellar matter.

Knapp, Gillian R.↗

NASA NTRS1987

Diffuse and dark clouds in the interstellar medium

Observations of clouds in the ISM of the Galaxy and the Magellanic Clouds, obtained with the IUE satellite since its launch in 1978, are reviewed. Consideration is given to the techniques used to analyze IUE Maxwellian growth curves and oscillator strengths, the general structure of the Galactic ISM, the high-velocity clouds, heavy-element depletion, and observations toward strongly reddened stars in the outer portions of dark clouds. Theoretical models of interstellar dust formation and selective and nonselective removal of elements from dust grains are discussed; observations of reflection nebulae and their implications for light scattering by dust are examined; the dynamics and ionization structure of the Galactic halo ISM are described; and the Magellanic Cloud observations are briefly characterized. Diagrams, graphs, and tables of numerical data are provided.

De Boer, Klaas S.↗