Motion of Dust Structures in the Circumnuclear Region of Comet Hale–Bopp and Rotation of the Cometary Nucleus

Abstract

The motion of dust structures in the circumnuclear region of comet Hale–Bopp is studied. About 270 envelope images were obtained with the AZT-8 reflector (D = 0.7 m, F = 28 m) and the Filin-3 image intensifier. We carried out our observations at the observational station of the Astronomical Observatory of Shevchenko Kiev State University in the village of Lesniki (near Kiev). The recording from the image-intensifier screen was made on Foto-100 film during 23 nights from March 24 to May 10, 1997. The circumnuclear region was imaged both in white light (without filters) and with IHW CO+ (λef = 426 nm), C3 (λef = 496 nm), C2 (λef = 514 nm), and RC (red continuum, λef = 684 nm) narrow-band interference filters. Based on our measurements of the radial expansion of dust structures, we determined the velocities, 0.61–1.99 km s–1; accelerations, from –18.3 × 10–3 to 4.0 × 10–3 m s–2; and rotation period of the cometary nucleus, 111.41h ± 0.05h.