The Physical Conditions and Metal Enrichment of Low-Redshift Interstellar and Intergalactic Media: The Benefits of High-Resolution Ultraviolet Spectra

To underscore the value of high spectral resolution for the study of low-z QSO absorption lines, we briefly present Space Telescope Imaging Spectrograph echelle data that demonstrate how increased resolution leads to dramatic improvement in line measurements. We show that even R = lambda/Delta lambda = 20,000 is insufficient for some measurements. The higher the resolution the better, but R ~ 50,000 is adequate for many outstanding questions about the IGM and the ISM of galaxies that can be probed using QSO absorption lines.