The development of a cocoon star

A newly-formed massive star is likely to be surrounded by dense gas and dust as it approaches the main sequence. Radiation pressure must push some of the inner material outward before the star begins to produce ionizing radiation; this affects the formation of theHii region. A remarkably dense dust front may precede the ionization front.The observable radio and infrared spectra are discussed. If the dust cloud is composed of small graphite grains, extraordinarily large far-infrared fluxes are possible.