High Resolution Far-Infrared Observations of the Ring Nebula

High spatial resolution 50 microns observations of the Ring Nebula, using the Kuiper Airborne Observatory, have revealed a far-infrared emission peak close to the center of the nebula, where atomic and molecular emission is at a minimum. Dust in central peak emission region is heated by direct absorption of the radiation from the central star. It is found that the majority of dust grains are located in the regions of the ionized nebular core and the neutral molecular gas. Lyman alpha photons are sufficient for heating the dust grains within the ionized region. Two possible scenarios with transient heating of small grains in the photodissociation region, and heating by shock- produced ultraviolet photons are proposed to explain the existence of dust mixed with the molecular gas outside the main ionized nebular core. This work was supported by NASA grant NAG 2-67.