Winds driven by super-star clusters: The self-consistent radiative solution

Here we present a self-consistent stationary solution for spherically symmetric winds driven by massive star clusters under the impact of radiative cooling. We demonstrate that cooling may modify drastically the distribution of temperature if the rate of injected energy approaches a critical value. We also prove that the stationary wind solution does not exist whenever the energy radiated away at the star cluster center exceeds ~ 30% of the energy deposition rate. Finally we thoroughly discuss the expected appearance of super-star cluster winds in the X-ray and visible line regimes. The three solutions here found: the quasi-adiabatic, the strongly radiative wind and the inhibited stationary solution, are then compared to the winds from Arches cluster, NGC 4303 central cluster and to the supernebula in NGC 5253.Comment: 9 pages, 5 figures, accepted for publication by The Astrophysical Journa

Supernovae and their expanding blast waves during the early evolution of Galactic globular clusters

Our arguments deal with the early evolution of Galactic globular clusters and show why only a few of the supernovae products were retained within globular clusters and only in the most massive cases ($M \ge 10^6$ Msol), while less massive clusters were not contaminated at all by supernovae. Here we show that supernova blast waves evolving in a steep density gradient undergo blowout and end up discharging their energy and metals into the medium surrounding the clusters. This inhibits the dispersal and the contamination of the gas left over from a first stellar generation. Only the ejecta from well centered supernovae, that evolve into a high density medium available for a second stellar generation in the most massive clusters would be retained. These are likely to mix their products with the remaining gas, leading in these cases eventually to an Fe contaminated second stellar generation.Comment: Accepted for publication in the Astrophysical Journal Letters, 10pages, 1 figur

The realm of the Galactic globular clusters and the mass of their primordial clouds

By adopting the empirical constraints related to the estimates of Helium enhancement ($\Delta Y$), present mass ratio between first and second stellar generations ($M_{1G}/M_{2G}$) and the actual mass of Galactic globular clusters ($M_{GC}$), we envisage a possible scenario for the formation of these stellar systems. Our approach allows for the possible loss of stars through evaporation or tidal interactions and different star formation efficiencies. In our approach the star formation efficiency of the first generation ($\epsilon_{1G}$) is the central factor that links the stellar generations as it not only defines both the mass in stars of the first generation and the remaining mass available for further star formation, but it also fixes the amount of matter required to contaminate the second stellar generation. In this way, $\epsilon_{1G}$ is fully defined by the He enhancement between successive generations in a GC. We also show that globular clusters fit well within a $\Delta Y$ {\it vs} $M_{1G}/M_{2G}$ diagram which indicates three different evolutionary paths. The central one is for clusters that have not loss stars, through tidal interactions, from either of their stellar generations, and thus their present $M_{GC}$ value is identical to the amount of low mass stars ($M_* \le$ 1 M$_\odot$) that resulted from both stellar generations. Other possible evolutions imply either the loss of first generation stars or the combination of a low star formation efficiency in the second stellar generation and/or a loss of stars from the second generation. From these considerations we derive a lower limit to the mass ($M_{tot}$) of the individual primordial clouds that gave origin to globular clusters.Comment: 17 pages, 2 figures, accepted for publication in the Astrophysical Journa