the goal of this proposal is to obtain a high signal-to-noise template of the emission from the interstellar medium of a normal isolated spiral. for the reasons explained at length below, we believe that ngc 4414 is the best candidate, largely due to the extremely complete data set at other wavelengths. as the dust is a major constituent of the ism, in terms of the exchanges of energy rather than in terms of mass, we begin by observing the 60, 90, and 105 micron emission with pht-c100 over an area which completely covers the galaxy and leaves a (probably) emission-free zone around the source. the sensitivity is such that low-level emission should be detected if present. then we investigate the emission in a very uncertain line, siii, with the sws02 aot, and simultaneously observe the reddening free pfund series halpha recombination line at 7.4578 microns in order to compare with ground-based halpha and hbeta lines for temperature and extinction effects. the true template aspect of this proposal is the full spectral scan from 43 to 196 microns with the lws. we have requested a fairly long integration time in order to detect weak lines and obtain high s/n observations of the stronger ones. these observations will help us understand the differences in the physical conditions and excitation of the dense gas in different types of galaxies. the results will be compared to model predictons of the line strengths and ratios.
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, BRAINE et al., 1999, 'THE INTERSTELLAR MEDIUM OF A NORMAL comma ISOLATED comma SPIRAL GALAXY THE ISM IN NGC 4414', 1.0, European Space Agency, https://doi.org/10.5270/esa-q8qsg2b
