Unbound Close Stellar Encounters in the Solar Neighborhood

TL;DR

This paper catalogs unbound stellar pairs within 100 parsecs of the Sun undergoing close, hyperbolic encounters, identifying potential targets for SETI searches based on stellar migration hypotheses.

Contribution

It provides the first comprehensive catalog of such stellar encounters using GAIA EDR3 data, highlighting specific single stars and known planet hosts as candidates for migration events.

Findings

132 close passage events identified

16 pairs include stars of spectral types K1 to F3

8 single stars identified as prime candidates for migration searches

Abstract

We present a catalog of unbound stellar pairs, within 100 pc of the Sun, that are undergoing close, hyperbolic, encounters. The data are drawn from the GAIA EDR3 catalogue, and the limiting factors are errors in the radial distance and unknown velocities along the line of sight. Such stellar pairs have been suggested (Hansen & Zuckerman 2021) to be possible events associated with the migration of technological civilisations between stars. As such, this sample may represent a finite set of targets for a SETI search based on this hypothesis. Our catalog contains a total of 132 close passage events, featuring stars from across the entire main sequence, with 16 pairs featuring at least one main sequence star of spectral type between K1 and F3. Many of these stars are also in binaries, so that we isolate eight single stars as the most likely candidates to search for an ongoing migration event -- HD 87978, HD 92577, HD 50669, HD 44006, HD 80790, LSPM J2126+5338, LSPM J0646+1829 and HD 192486. Amongst host stars of known planets, the stars GJ 433 and HR 858 are the best candidates.