A surprise in the updated list of stellar perturbers of long period comets motion

Abstract

The second Gaia data release (Gaia DR2) provided us with the precise five-parameter astrometry for 1.3 billion of sources. As stars passing close to the Solar System are thought to be responsible for influencing the dynamical history of long period comets, we update and extend the list of stars that could potentially perturb motion of these comets. We aim to announce a publicly available database containing an up to date list of stars and stellar systems potentially perturbing long period comets motion. We add new objects and revise previously published lists. Special emphasis was placed on stellar systems. Discussion on masses estimation is included. Using the astrometry, preferably from Gaia DR2, augmented with data from other sources, we calculate spatial positions and velocities for each star. To filter studied objects on the basis of their minimal heliocentric distances we numerically integrate motion of stars under the Galactic potential and their mutual interactions. We announce the updated list of stellar perturbers of cometary motion, including masses of perturbers along with the publicly available database interface. These data are ready to be used with the observed long period comets orbits to study an individual influence of a whole sample of perturbers, or specific stars, on a dynamical past or future of a specific comet. 147 new perturbers were added in comparison to the previously published sources. We demonstrate that a new set of potential perturbers constitute an important tool in studies of cometary dynamics. The usage of our data significantly changes results of the past and future comet motion analysis. We point out a puzzling object in our list, star ALS 9243. The Gaia DR2 astrometry suggests a very close encounter of this star with the Sun however, its astrophysical parameters result in a completely different current distance of ALS 9243 and its large mass.