Atomic carbon in the envelope of IRC + 10216

We report observations of the ³P1 → ³P0 transition of atomic carbon at 492 GHz in IRC + 10216, made at the Caltech Submillimeter Observatory. The C I emission from the central position of IRC + 10216 was found to have a main beam temperature of about 0.4 K and to be doubly peaked at the expansion velocity of the CO envelope. Its spatial distribution can be modeled by two shells of radius ∼15″ and 45″ with column densities to the central star in the ³P1 state of 7 x 10¹⁵ and 4 x 10¹⁵ cm^-2, respectively. Based on comparison of our data with a recent photodissociation and chemical calculation of the abundances in the circumstellar envelope, we suggest that the two shells may be due to photodissociation of acetylene and carbon monoxide, respectively, but appearing at smaller radii than predicted.

Duke Scholars

Author Ken H Young Pathology