CIRRUS COLOR VARIATIONS DUE TO ENHANCED RADIATION-FIELDS

We have investigated the variations in 12/100, 25/100, 60/100, and 12/ 25 mu m colors for seven main-sequence B stars and three F and G super giants associated with infrared cirrus. All sources displayed an incre ase in 60/100 color above the background cirrus color. In two of the s ources, epsilon Apodis and HR 890, the 12/100 and 25/100 colors declin e toward the embedded star in a similar fashion to the IR colors of S2 64 and the Rosette Nebula. Current grain models composed of equilibriu m-heated submicron grains, transiently heated small grains, and polycy clic aromatic hydrocarbons cannot account for the color variations obs erved around epsilon Aps and HR 890. The supergiants exhibited 12/100 and 25/100 increases, suggesting that the color deficits observed for the B stars are due to an enhancement in the soft UV component of the radiation field only. A candidate explanation for the color variations is a conglomerate small grain component, composed of very small grain s and/or large molecules, that is fragmented in the enhanced radiation field around epsilon Aps and HR 890.