We have obtained R-band coronagraphic images of
fragments of comet SL9 inside the Jovian magnetosphere.
We used the University of Hawaii 2.2 meter telescope
on Mauna Kea under sub-arcsecond seeing conditions.
Observations were taken UT 94/07/19.2 - 19.3 using coronagraphic
optics.
Fragments P2, Q1, Q2, S, R and W were detected at high signal/noise ratio. Fragments N, P1, T, U and V were beneath our detection limit, while L fell outside the fields of view employed. Images of fragment K were obtained 2 hours prior to impact. Astrometry has been communicated to Paul Chodas et al, for all observed fragments except K. The non-appearance of V is surprising, based on its pre-entry brightness (comparable to W).
The fragments now resemble aligned tadpoles, with the tails pointing towards Jupiter along the axis of the comet string (i.e. the tadpoles are falling into Jupiter tail-first). We see no evidence for the radiation pressure-swept dust tails that have dominated the morphology since early 1994. The tadpole morphology is most pronounced for Q1 and S, but is probably present in all nuclei. Our images presumably trace the distribution of large "dust" or boulder-sized solids that are immune to scattering by the Lorenz force. Preliminary photometry provides no evidence that the central (1 arcsec) cores of the fragments have faded since immersion in the magnetosphere, although further work will be needed to clarify this point.
David Jewitt and Paul Kalas (University of Hawaii)