HIGH-RESOLUTION IMAGERY OF BD -DEGREES-3639 AND ITS DUSTY HALO(30)

The planetary nebula BD +30 degrees 3639 has been imaged by the Hubble Space Telescope through nine narrow-band filters. A high-resolution r adio map has been obtained with the VLA. Comparison of H beta, H alpha , and radio images allow us to derive the point-to-point variations in both the extinction and the ratio of total to selective absorption. T he extinction shows (1) a gradient across the nebula, and (2) a large dust clump in the northeast and many small (similar to 0.'' 2) dust fe atures. The ratio of total to selective absorption for this nebula is close to the normal ISM value, and can be modeled by a power law distr ibution of amorphous carbon grains. It is found that the optical image s show a substantial halo due to light scattered by dust in the neutra l envelope surrounding the ionized shell. Monte Carlo models indicate that such scattering could result from a dust halo with an optical dep th of unity and an albedo of similar to 0.4. Such a high albedo is not consistent with pure carbon dust models. The halo images in [O I] lam bda 6300 and [S II] lambda 6717,31 show anomalous structures not seen in the other lines, which seem to be in emission. The strongest [O I] feature is coincident with halo emission previously observed in the 1- 0 S(1) transition of H-2. The [O I] and [S II] emission may indicate s hock heating of the halo. (C) 1997 American Astronomical Society.