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Unsupervised Kinematic Dissection of the Solar Neighborhood: Identifying Stellar Moving Groups with Gaia DR3

Anmay Raj

TL;DR

This paper investigates the solar neighborhood's kinematic structure using Gaia DR3's full 6D phase-space data within 50 pc. It applies a density-based unsupervised clustering method (DBSCAN) in velocity space to identify overdensities corresponding to moving groups without relying on prior membership assumptions. The analysis successfully recovers the Hyades and Pleiades streams as distinct kinematic cores, characterizes their velocity dispersions, and demonstrates a structured local velocity field. The results validate unsupervised clustering as a robust tool for mapping the disk's dynamical history and provide high-confidence member catalogs for future spectroscopic studies.

Abstract

We present a comprehensive kinematic analysis of the solar neighborhood (d < 50 pc) using high-precision astrometric data from the third Gaia Data Release (DR3). By leveraging the full six dimensional phase space information (positions and velocities), we apply the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm to blindly identify stellar overdensities in the Galactocentric Cartesian velocity space (U, V, W ). Our unsupervised machine learning approach successfully recovers the kinematic cores of major local moving groups, including the Hyades and Pleiades streams, without prior assumptions regarding their membership or spatial distribution. We analyze the velocity dispersion and structural properties of these associations, demonstrating that automated clustering algorithms are robust tools for mapping the complex dynamical history of the local Milky Way disk. These results confirm the hierarchical nature of stellar kinematic substructures and provide a catalog of high-probability members for future spectroscopic follow-up.

Unsupervised Kinematic Dissection of the Solar Neighborhood: Identifying Stellar Moving Groups with Gaia DR3

TL;DR

This paper investigates the solar neighborhood's kinematic structure using Gaia DR3's full 6D phase-space data within 50 pc. It applies a density-based unsupervised clustering method (DBSCAN) in velocity space to identify overdensities corresponding to moving groups without relying on prior membership assumptions. The analysis successfully recovers the Hyades and Pleiades streams as distinct kinematic cores, characterizes their velocity dispersions, and demonstrates a structured local velocity field. The results validate unsupervised clustering as a robust tool for mapping the disk's dynamical history and provide high-confidence member catalogs for future spectroscopic studies.

Abstract

We present a comprehensive kinematic analysis of the solar neighborhood (d < 50 pc) using high-precision astrometric data from the third Gaia Data Release (DR3). By leveraging the full six dimensional phase space information (positions and velocities), we apply the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm to blindly identify stellar overdensities in the Galactocentric Cartesian velocity space (U, V, W ). Our unsupervised machine learning approach successfully recovers the kinematic cores of major local moving groups, including the Hyades and Pleiades streams, without prior assumptions regarding their membership or spatial distribution. We analyze the velocity dispersion and structural properties of these associations, demonstrating that automated clustering algorithms are robust tools for mapping the complex dynamical history of the local Milky Way disk. These results confirm the hierarchical nature of stellar kinematic substructures and provide a catalog of high-probability members for future spectroscopic follow-up.

Paper Structure

This paper contains 14 sections, 1 figure.

Table of Contents

  1. Introduction
  2. Data and Sample Selection
  3. Gaia Data Release 3
  4. Sample Criteria
  5. Methodology
  6. Coordinate Transformation
  7. DBSCAN Clustering
  8. Results and Discussion
  9. Global Velocity Distribution
  10. Identified Moving Groups
  11. The Hyades Stream
  12. The Pleiades Stream
  13. Comparison with Literature
  14. Conclusion

Figures (1)

  • Figure 1: Velocity distribution of stars in the solar neighborhood ($U$ vs $V$). The grey points represent the background field stars, while the colored points indicate the clusters identified by DBSCAN. The prominent overdensities correspond to the Hyades and Pleiades moving groups.