A catalogue of close encounter pairs

TL;DR

This paper compiles a detailed catalogue of star pairs with close periapses within 1 parsec over the past or next 100 million years, revealing anisotropic encounter directions influenced by solar motion.

Contribution

It introduces a comprehensive catalogue of close stellar encounter pairs using astrometric and radial velocity data, highlighting the anisotropic nature of encounters due to solar motion.

Findings

Identified 4 encounters with the Solar System within 1 pc.

Discovered 96 pairs with periapses less than 0.1 pc.

Detected anisotropy in encounter directions caused by solar apex motion.

Abstract

We provide a catalogue of pairs of stars whose periapses are less than 1pc within the past or future 100 Myr. We use astrometric data from TGAS, Hipparcos and radial velocity data from RAVE and XHIP to find the space motions and hence the initial conditions of 229, 441 stars in Galactic coordinates. We simulate the orbits of these stars and focus on the time, distance and velocity at periastron for 8149 pairs using the k-d tree algorithm to find nearest neighbors. We find an anisotropy in the directions of encounter pairs caused by the solar apex motion, indicating a role of peculiar motion imposing an anisotropic tidal force on planetary systems. We call this effect "kinematic tide". Among the encounter pairs there are 4 encounters with the Solar System with periapses less than 1 pc and 96 pairs with periapses less than 0.1 pc. We also find 577 close encounters of stars which host planetary systems and/or debris disks. We discuss a range of uses for an encounter catalogue and present an example of how the time-varying network of stellar motions will be crucial for efficient interstellar travel between planetary systems. The catalogues are available at http://star.herts.ac.uk/pandora/cep1.