Beverly Smith (IPAC) has written the following summary of her observations...
In collaboration with Suzanne Madden (Saclay, France) and her research team, I am using the Infrared Space Observatory to obtain far-infrared spectroscopic measurements of irregular galaxies and low luminosity Virgo spirals. These galaxies have low proportions of heavy elements in their interstellar medium compared to more massive galaxies such as the Milky Way.
For comparison with these data, we used the NRAO 12 meter telescope on Kitt Peak in Arizona to measure the 2.6 millimeter line of carbon monoxide in some of these galaxies.
Some initial results on 5 spiral galaxies in the Virgo Cluster are presented below (from B. J. Smith and S. C. Madden, 1997, Astronomical Journal, in press). Notice that the relative CO and [C II] line strengths differ from galaxy to galaxy. The optical images are from the Digitalized Palomar Observatory Sky Survey and are 3.1 arcminutes in diameter.
| Galaxy | Optical Image | 2.6mm CO Spectrum | 158 micron [C II] Spectrum |
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| NGC 4189 |
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| NGC 4222 |
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| NGC 4294 |
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| NGC 4299 |
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| NGC 4522 |
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