we propose to observe atomic and ionic fine structure lines in nearby external galaxies. our observations will address two particular ascpects of the interstellar medium in these galaxies. first, an oversampled raster map of the grand design spiral galaxy m51 in the 158 micron cii, the 122 micron nii, and the 63 and 146 micron oi fine structure lines will, by deconvolution, allow us to determine arm / interarm variations in the physical conditions and excitation mechanisms of the warm, mainly neutral interstellar medium and in the uv radiation field strength and spectral distribution. this information will contribute to the understanding of the mechanisms that drive star formation in spiral patterns. second, deep integration of the cii and nii fine structure line emission from the extended medium im m83 and centaurus a will for the first time allow us to discern the cold, dense, neutral medium from the thinner, partly or fully ionized phases of the extended atomic medium as sources of cii line emission. temperatures and densities of the cold neutral medium in the outer disks of external galaxies will be derived for the first time. in an analogous way, the physical conditions of the neutral atomic gas associated with the shells of centaurus a will be explored.
Instrument
LWS02
Temporal Coverage
1997-08-07T01:26:04Z/1997-08-11T01:40:41Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, POGLITSCH et al., 1999, 'SPECTRAL LINE MAPPING AND THE EXTENDED MEDIUM IN NEARBY GALAXIES', 1.0, European Space Agency, https://doi.org/10.5270/esa-huq2f5w
