To test the cooling flow model of early-type galaxies, we obtained a complete magnitude-limited sample of 34 early-type galaxies, observed with the PSPC and HRI on ROSAT. The X-ray to optical distribution of galaxies implies a lower envelope that is consistent with the stellar emission inferred from Cen A. When this stellar component is removed, the gaseous emission is related to the optical luminosity by L X ∝ L m B , where m = 3.0-3.5, significantly steeper than the standard theory (m = 1.7). The dispersion about the correlation is large, with a full range of 30-100 in L X for fixed L B . The X-ray temperature is related to the velocity dispersion temperature as T X ∝ T n σ , where n = 1.43±0.21, although for several galaxies, T X is about twice T σ . The excessively hot galaxies are generally the most luminous and are associated with the richest environments. We suggest a model whereby environment influences the X-ray behavior of these galaxies: early-type galaxies attempt to drive partial or total galactic winds, which can be stifled by the pressure of their environment. Stifled winds should lead to hotter and higher luminosity systems, which would occur most commonly in the richest environments, as observed.

In order to further our understanding of the phenomena of X-ray emission from early-type galaxies, we obtained an optically Ñux-limited sample of 34 elliptical and S0 galaxies, observed with high and low angular resolution detectors on ROSAT . Our previous analysis of this sample suggested that the most X-rayÈluminous galaxies were in rich environments. Here we investigate environmental inÑuences quantitatively and Ðnd a positive correlation between and the local galaxy density. Since the local L X /L B galaxy density is usually related to the density of hot intergalactic gas, we suggest that this correlation occurs because the X-ray luminosity is enhanced, either through accretion of the intergalactic gas or because the ambient medium stiÑes galactic winds. When the ambient medium is unimportant, partial or global galactic winds can occur, reducing These e †ects lead to the large observed dispersion inWe discuss details of the data processing not previously presented, and examine the L X L B . dependence of on the choice of outer source radius and background location. We also compare the L X temperature deduced for these galaxies from di †erent analyses of ROSAT and ASCA data. The ASCA and ROSAT temperatures are found to be similar, provided that the same metallicities and Galactic absorption columns are used.

We present new measurements of isotopic shifts and hyperfine structure in the lead resonance line for a total of 15 isotopes. The experimental accuracy is of order 4 MHz. Using independent measurements of the nuclear parameter A for the stable isotopes we have derived A for all measured isotopes.