---
author:
- 'Melvin G. Hoare'
- José Franco
title: Massive Star Formation
---

Introduction
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The formation and evolution of massive ($>10$M) stars plays a key role in the final fate of their parental molecular clouds, and in the appearance and evolution of their host galaxies. They inject large amounts of mechanical and radiative energy creating, either by a single star or a stellar cluster, the most spectacular gaseous nebulae in the Cosmos. Also, they generate fast shocks which heat up the surrounding plasma to temperatures above 10$^6$ K, and carve large interstellar “holes” that continuously stir the general interstellar medium.

From the moment they are born their powerful outflows begin to plough into the surrounding molecular material. Similarly, the output of Lyman continuum radiation, that sets them apart from lower mass stars, ionize the cloud and form a dense and hot H II region. The expansion of this photoionized nebula drives a shock wave that both compress and may trigger further star formation on the one hand, and disperse a large portion of the molecular cloud on the other. As the new OB star enters the field population its winds and ultra-violet radiation continue to influence the general 