Abstract
Numerical simulations of the evolving activity of comet Hale-Bopp are presented, assuming a porous, spherical nucleus, 20 km in radius, made of dust and gas-laden amorphous ice. The main effects included are: crystallization of amorphous ice and release of occluded gas, condensation, sublimation and flow of gases through the pores, changing pore sizes, and flow of dust grains. The model parameters, such as initial pore size and porosity, emissivity, dust grain size, are varied in order to match the observed activity. In all cases, a sharp rise in the activity of the nucleus occurs at a large heliocentric distance pre-perihelion, marked by a few orders of magnitude increase in the CO and the CO2 fluxes and in the rate of dust emission. This is due to the onset of crystallization, advancing down to a few meters below the surface, accompanied by release of the trapped gases. A period of sustained, but variable, activity ensues. The emission of water molecules is found to surpass that of CO at a heliocentric distance of 3 AU. Thereafter the activity is largely determined by the behaviour of the dust. If a dust mantle is allowed to build up, the water production rate does not increase dramatically towards perihelion; if most of the dust is ejected, the surface activity increases rapidly, producing a very bright comet.
Article PDF
Similar content being viewed by others
References
Bar-Nun, A., Dror, J., Kochavi, E., and Laufer, D.: 1987, Phys. Rev. 35, 2427.
Biver, N., Bockelée-Morvan, D., Colom, P., Crovisier, J., Davies, J. K., Dent, W. R. F., Despois, D., Gérard, E., Lellouch, E., Rauer, H., Moreno, R., and Paubert, G.: 1997, Science 275, 1915.
Biver, N. et al.: 1997–1999, Earth, Moon, and Planets 78, in press.
Crovisier, J., Leech, K., Bockelée-Morvan, D., Brooke, T. Y., Hanner, M. S., Altieri, B., Keller, H.-U., and Lellouch, E.: 1997, Science 275, 1904.
Huebner, W. F. and Benkhoff, J.: 1997–1999, Earth, Moon, and Plantes 77, 217–222.
Jewitt, D., Senay, M., and Matthews, H.: 1996, Science 271, 1110.
Kidger, M. R., Serra-Ricart, M., Bellot-Rubio, L. R., and Casas, R.: 1996, ApJ 461, L119.
Marsden, B. G.: 1997–1999, Earth, Moon, and Planets 79, in press.
Mekler, Y. and Podolak, M.: 1994, Planet. Space Sci. 42, 865.
Mekler, Y., Prialnik, D., and Podolak, M.: 1990, ApJ 356, 682.
Podolak, M. and Prialnik, D.: 1996, Planet. Space Sci. 44, 655.
Prialnik, D.: 1992, ApJ 388, 196.
Prialnik, D.: 1997, ApJ 478, L107.
Prialnik, D. and Bar-Nun, A.: 1990, ApJ 363, 274.
Prialnik, D., Brosch, N., and Ianovici, D.: 1995, MNRAS 276, 1148.
Prialnik, D., Egozi, U., Bar-Nun, A., Podolak, M., and Greenzweig, Y.: 1993, Icarus 106, 499.
Rauer, H., Arpigny, C., Boehnhardt, H., Colas, F., Crovisier, J., Jorda, L., Küppers, M., Manfroid, J., Rembor, K., and Thomas, N.: 1997, Science 275, 1909.
Weaver, H. A., Feldman, P. D., A'Hearn, M. F., Arpigny, C., Brandt, J. C., Festou, M. C., Haken, M., McPhate, J. B., Stern, S. A., and Tozzi, G. P.: 1997, Science 275, 1900.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Prialnik, D. Modelling Gas And Dust Release From Comet Hale–Bopp. Earth, Moon, and Planets 77, 223–230 (1997). https://doi.org/10.1023/A:1006224000795
Issue Date:
DOI: https://doi.org/10.1023/A:1006224000795