CAOSP abstracts, Volume: 39, No.: 2, year: 2009

Abstract: The distant comet reservoir, Oort cloud, is perturbed by the Galactic tide, nearly passing stars, and giant interstellar molecular clouds. The perturbations by the latter are least frequent, but their amplitude is expected to be highest. In this work, we consider two models of a dense region of a giant molecular cloud and investigate its gravitational effect on the cometary Oort cloud, when the Solar System passes through. Since the comets in the Oort cloud prevailingly move in orbits with high galactic inclinations, we consider two geometries of the encounter differing in this aspect. Since the outer border of a relatively concentrated part of the real Oort cloud is estimated at ∼ 50 000 AU in terms of the semi-major axis, a, its passage through the central region of a giant molecular cloud does not, according to our simulations, significantly erode the Oort cloud. Although, it can change its structure for a ⪆ 10^4.4 AU. In our simulations, some changes depend on the model considered. For the Plummer model, the giant-molecular-cloud gravity caused an enlargement of the dispersion of galactic inclination and is selective to the specific values of the galactic argument of perihelion.