A radio continuum and H i study of IC 63, IC 59, and IRAS 00556 + 6048: nebulae in the vicinity of γ Cas

Sh 185, which is associated with the B0-B0.5IV star γ Cas and contains the two nebulae IC 63 and IC 59, has been observed with the DRAO synthesis telescope in continuum emission at 408 and 1420 MHz, and in H i line emission. Continuum emission is clearly detected for IC 63 and weakly detected for IC 59. The emission from both nebulae is thermal, with the masses of ionized gas being 0.08 and 0.07 M⊙, respectively. The masses of Hi detected are 0.15 M⊙ for IC 63, and 0.64 M⊙ for IC 59. Infrared emission was detected in the IRAS survey from both IC 63 and IC 59, and also from a point source, IRAS 00556 + 6048, located between the two clouds. The infrared and radio luminosities of IC 63 and IC 59 are consistent with the heating and ionization being produced by γ Cas. However, the time required to produce the observed H i through photodissociation is less than any reasonable age for γ Cas by orders of magnitude. This suggests that the nebulae are density bounded and the production of H i through photodissociation by radiation from γ Cas has mostly ceased. The exception occurs in a small region of molecular gas in IC 63, where extended red emission and molecular hydrogen fluorescent emission are still observed. H i is also detected near IRAS 00556 + 6048. This H i appears to be associated with the infrared source, and with a velocity of — 34 km s−1 suggests that the infrared source is not associated with Sh 185. The exciting star for IRAS 00556 + 6048 may be another example of a dissociating star.