On the population, physical decay and orbital distribution of Jupiter family comets: Numerical simulations

ROMINA P. DI SISTO A, JULIO A. FERNÁNDEZ , ADRIÁN BRUNINI

ICARUS

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: New York; Año: 2009 vol. 203 p. 140 - 154

0019-1035

We study the Jupiter family comet (JFC) population assumed to come from the Scattered Disk and transferredto the Jupiter?s zone through gravitational interactions with the Jovian planets. We shall define asJFCs those with orbital periods P < 20 yr and Tisserand parameters in the range 2 < TK3:1, while thosecomets coming from the same source, but that do not fulfill the previous criteria (mainly because theyhave periods P > 20 yr) will be called ?non-JFCs?. We performed a series of numerical simulations of fictitiouscomets with a purely dynamical model and also with a more complete dynamical?physical modelthat includes besides nongravitational forces, sublimation and splitting mechanisms. With the dynamicalmodel, we obtain a poor match between the computed distributions of orbital elements and the observedones. However with the inclusion of physical effects in the complete model we are able to obtain good fitsto observations. The best fits are attained with four splitting models with a relative weak dependence onq, and a mass loss in every splitting event that is less when the frequency is high and vice versa. The meanlifetime of JFCs with radii R > 1 km and q < 1:5 AU is found to be of about 150?200 revolutions (103 yrÞ.The total population of JFCs with radii R > 1 km within Jupiter?s zone is found to be of 450 50. Yet, thepopulation of non-JFCs with radii R > 1 km in Jupiter-crossing orbits may be 4 times greater, thus leadingto a whole population of JFCs + non-JFCs of 2250 250. Most of these comets have perihelia close toJupiter?s orbit. On the other hand, very few non-JFCs reach the Earth?s vicinity (perihelion distancesqK2 AU) which gives additional support to the idea that JFCs and Halley-type comets have differentdynamical origins. Our model allows us to define the zones of the orbital element space in which wewould expect to find a large number of JFCs. This is the first time, to our knowledge, that a physicodynamicalmodel is presented that includes sublimation and different splitting laws. Our work helpsto understand the role played by these erosion effects in the distribution of the orbital elements and lifetimesof JFCs.