[C II] 158-μm observations of a sample of late-type galaxies from the Virgo cluster

We have observed 19 Virgo cluster spiral galaxies with the Long Wavelength Spectrometer (LWS) onboard ESA's Infrared Space Observatory (ISO) obtaining spectra around the [C II] 157.741-mu m fine-structure line. These 19 galaxies are quiescent in star-forming activity compared with previous studies from airborne observatories, sample RC3 types 0 to 5 and come from both the cluster core and the cluster periphery. The sample enables us to probe any difference in the [C II] emission between different RC3 types or between core and periphery galaxies. 14 of the 19 galaxies were detected in the [C II] line. Any influence of the Virgo cluster environment on the [C II] emission was found to be small compared with the strong dependence of the line emission on basic measurables such as morphology or bulk mass of the stellar component, as measured by the near-IR (K'-band) luminosity. While the range of the [C II]-to-far-IR ratio is less than in other surveys (reflecting the fact these galaxies are relatively quiescent), there is a good correlation between the strength of the [C II] line and the far-IR flux, as measured by IRAS (FIR). We find a trend of increasing [C II]-to-FIR flux ratio with increasing galaxy lateness. Moreover, the [C II]-to-K'-band flux ratio shows a two order of magnitude difference between RC3 type 0 and RC3 types later than 5. These two correlations express the relation between the mechanism of the [C II] emission and the massive star formation activity of the galaxy.