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arXiv:2206.11248 [astro-ph.GA]AbstractReferencesReviewsResources

The Gaia DR3 view of dynamical substructure in the stellar halo near the Sun

Emma Dodd, Thomas M. Callingham, Amina Helmi, Tadafumi Matsuno, Tomas Ruiz-Lara, Eduardo Balbinot, Sofie Lovdal

Published 2022-06-22Version 1

The debris from past merger events is expected and, to some extent, known to populate the stellar halo near the Sun. We aim to identify and characterise such merger debris using Gaia DR3 data supplemented by metallicity and chemical abundance information from LAMOST LRS and APOGEE for halo stars within 2.5 kpc from the Sun. We utilise a single linkage-based clustering algorithm to identify over-densities in Integrals of Motion space that could be due to merger debris. Combined with metallicity information and chemical abundances, we characterise these statistically significant over-densities. We find that the local stellar halo contains 8 main dynamical groups, some of in-situ and some of accreted origin, most of which are already known. We report the discovery of a new substructure, which we name ED-1. In addition, we find evidence for 9 independent smaller clumps, 4 of which are new: ED-2, 3, 4 and 5 are typically rather tight dynamically, depict a small range of metallicities, and their abundances when available, as well as their location in Integrals of Motion space suggest an accreted origin.

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