Stellar Flyby Analysis for Spiral Arm Hosts with Gaia DR3

TL;DR

This study uses Gaia DR3 data to analyze stellar flyby histories of spiral arm systems in circumstellar disks, finding that recent close stellar flybys are unlikely the main cause of these spirals.

Contribution

It introduces an analytical on-sky flyby framework leveraging Gaia DR3 data to assess flyby influence on spiral arms in circumstellar disks.

Findings

No credible recent flyby candidates for isolated systems.

Close-in recent flybys are unlikely the main formation mechanism.

Most spiral arms are not caused by recent stellar flybys.

Abstract

Scattered light imaging studies have detected nearly two dozen spiral arm systems in circumstellar disks, yet the formation mechanisms for most of them are still under debate. Although existing studies can use motion measurements to distinguish leading mechanisms such as planet-disk interaction and disk self-gravity, close-in stellar flybys can induce short-lived spirals and even excite arm-driving planets into highly eccentric orbits. With unprecedented stellar location and proper motion measurements from Gaia DR3, here we study for known spiral arm systems their flyby history with their stellar neighbours by formulating an analytical on-sky flyby framework. For stellar neighbors currently located within 10 pc from the spiral hosts, we restrict the flyby time to be within the past $10^4$ yr and the flyby distance to be within $10$ times the disk extent in scattered light. Among a total of $12570$ neighbors that are identified in Gaia DR3 for $20$ spiral systems, we do not identify credible flyby candidates for isolated systems. Our analysis suggests that close-in recent flyby is not the dominant formation mechanism for isolated spiral systems in scattered light.