Research Note

An additional term of the Galactic tide due to dark matter

Astronomical Institute, Slovak Academy of Sciences, 05960 Tatranská Lomnica, Slovakia
e-mail: ne@ta3.sk

Received: 29 July 2011
Accepted: 12 September 2011

Abstract

Aims. We aim to complete the formula characterizing the Galactic tide acting on the comets in the Oort Cloud with the term that describes the action of dark matter in the Galaxy.

Methods. We analytically derive this term and gauge its amplitude for the current Galactic location of the Sun.

Results. The amplitude of the new component of the tide, which acts in the radial direction from the Galactic centre, is estimated to be about 15% lower than that of the old, commonly considered radial component, so it should not be neglected in a precise calculations. And, since it depends on the distance r from the Galactic centre as r^-2, it should certainly be considered when the Oort-Cloud dynamics is studied on a long-time scale assuming a radial migration of the Sun to shorter galactocentric distances.