I derive constraints on jet properties for inflating pairs of bubbles in
planetary nebulae and clusters of galaxies. This work is motivated by the
similarity in morphology and some non-dimensional quantities between
X-ray-deficient bubbles in clusters of galaxies and the optical-deficient
bubbles in planetary nebulae, which was pointed out in an earlier work. In the
present paper I find that for inflating fat bubbles, the opening angle of the
jets must be large, i.e., the half opening angle measured from the symemtry
axis of the jets should typically be larger than 40 degrees. Narrow jets will
form elongated lobes rather than fat bubbles. I emphasize the need to include
jets with large opening angle in simulating bubble inflation in both planetary
nebulae and (cooling flow) clusters of galaxies.Comment: submitted to AA; a second in a series of 3 paper