To appear in Reviews in Modern Astronomy 14, 2001? ed. Schielicke R.E., Springer-Verlag, astro-ph/0104387

Abstract. Dwarf galaxies provide a special environment due to their low mass, small size and generally low metal content. These attributes make them perfect laboratories for the interaction of massive stars with the interstellar medium on small and especially large spatial scales. The natural result of the spatially concentrated energy output from stellar winds and supernovae of an OB association is an expanding bubble. These bubbles can grow to kpc-size and become the dominant driver of the chemical and dynamical evolution of dwarf galaxies. In such low mass systems, bubbles have an enhanced probability of breaking out of the gaseous disk into the halo of the host galaxy. This may lead to venting metal enriched hot gas to large distances from the sites of creation. In this work I review the current observational material on hot gas inside bubbles, blow-outs, and hot halos of dwarf galaxies and discuss several conclusions which can be drawn from the observations. I will also present an analysis of the dwarf galaxy NGC 1705 as a case study, highlighting observational methods and problems with the current data. Finally I will comment on some areas where large progress should be possible in the near future.

Table of Contents

INTRODUCTION

OB ASSOCIATIONS AND THE INTERSTELLAR MEDIUM

HOT DIFFUSE GAS

Observations

Diffuse gas and outflows

Diffuse hot halos

Integral spectra

DIFFUSE WARM GAS

CONCLUSIONS AND OUTLOOK

REFERENCES

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