D. Blouin et al., A RADIO-CONTINUUM AND H-I STUDY OF IC-63, IC-59, AND IRAS-00556- NEBULAE IN THE VICINITY OF GAMMA-CAS(6048 ), Monthly Notices of the Royal Astronomical Society, 287(2), 1997, pp. 455-471
Sh 185, which is associated with the B0-B0.5IV star gamma Cas and cont
ains the two nebulae IC 63 and IC 59, has been observed with the DRAG
synthesis telescope in continuum emission at 408 and 1420 MHz, and in
H I line emission. Continuum emission is clearly detected for IC 63 an
d 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 H I 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 be
tween the two clouds. The infrared and radio luminosities of IC 63 and
IC 59 are consistent with the heating and ionization being produced b
y gamma Cas. However, the time required to produce the observed H I th
rough photodissociation is less than any reasonable age for gamma Cas
by orders of magnitude. This suggests that the nebulae are density-bou
nded and the production of H I through photodissociation by radiation
from gamma Cas has mostly ceased. The exception occurs in a small regi
on of molecular gas in IC 63, where extended red emission and molecula
r hydrogen fluorescent emission are still observed. H I is also detect
ed 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.