Dust emission nebulae around Orion O and B stars.

Intense long-wave radiation (8-20 has been found arising from regions surrounding six early stars in the Orion Nebula. The emission regions are very red and have angular sizes up to 25 seconds of arc. The [2.3 ] - [18 ] colors are between 8 and 10 mag, and in most cases the silicate emission feature is in evidence. Twenty other early stars were observed, and none showed the long-wave excess. The Orion Trapezium region seems unique. It is suggested that the radiation pressure of the stars is balanced by the kinetic pressure of the high-density gas in the surrounding H ii region. Subject headings: early-type stars - infrared sources - nebulae - Orion Nebula