University of Leicester
Browse
stac3649.pdf (10.29 MB)

New stellar velocity substructures from Gaia DR3 proper motions

Download (10.29 MB)
journal contribution
posted on 2024-03-05, 11:27 authored by D Mikkola, PJ McMillan, D Hobbs
Local stellar motions are expected, and have been shown, to include signatures of the Galaxy’s past dynamical evolution. These are typically divided into the disc, which shows the dynamical effects of spiral arms and the bar, and the stellar halo, with structures thought to be debris from past mergers. We use Gaia Data Release 3 to select large samples of these populations without limiting them to sources with radial velocities. We apply a penalized maximum likelihood method to these samples to determine the full 3D velocity distribution in Cartesian (U, V, and W) or spherical (vr, vφ, and vθ) coordinates. We find that the disc population is dominated by four moving groups and also detect a new moving group at (U, V) = (−10, −15) km s−1 which we call MMH-0. For the stellar halo, we isolate the accreted component with cuts in transverse velocity and the colour–magnitude diagram. In this component, we find several known structures believed to be caused by past mergers, particularly one around (vr, vφ, vθ) = (−150, −300, and −100) km s−1 appears more prominent than previously claimed. Furthermore, we also identify two new structures near (vr, vφ, and vθ) = (225, 25, and 325) km s−1 and (0, 150, and −125) km s−1, which we refer to as MMH-1 and MMH-2, respectively. These results give new insights into local stellar motions and shows the potential of using samples that are not limited to stars with measured line-of-sight velocities, which is key to providing large samples of stars, necessary for future studies.

Funding

Swedish Research Council (Vetenskapradet ˚ Reg: 2017-03721 and 2021-04153)

Swedish National Space Agency (SNSA Dnr 74/14 and SNSA Dnr 64/17)

History

Citation

Monthly Notices of the Royal Astronomical Society, Volume 519, Issue 2, February 2023, Pages 1989–2003

Author affiliation

Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Volume

519

Issue

2

Pagination

1989 - 2003

Publisher

Oxford University Press (OUP)

issn

0035-8711

eissn

1365-2966

Acceptance date

2023-12-03

Copyright date

2022

Available date

2024-03-05

Language

en

Deposited by

Mr Paul McMillan

Deposit date

2024-02-12

Data Access Statement

All data analysed in this paper are publicly available from the Gaia archive (http://gea.esac.esa.int/archive/). The 3D probability distributions used in Figs 3 and 5 are available upon request to the corresponding author.

Rights Retention Statement

  • No

Usage metrics

    University of Leicester Publications

    Categories

    Licence

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC