Skip to main content

Research Repository

Advanced Search

The biggest Splash

Grand, Robert J.J.; Evans, N. Wyn; Deason, Alis J.; Smith, Martin C.; Fattahi, Azadeh; Sanders, Jason L.; Belokurov, Vasily

The biggest Splash Thumbnail


Authors

Robert J.J. Grand

N. Wyn Evans

Martin C. Smith

Jason L. Sanders

Vasily Belokurov



Abstract

Using a large sample of bright nearby stars with accurate Gaia Data Release 2 astrometry and auxiliary spectroscopy we map out the properties of the principle Galactic components such as the “thin” and “thick” discs and the halo. We confirm previous claims that in the Solar neighborhood, there exists a large population of metal-rich ([Fe/H]>−0.7) stars on highly eccentric orbits. By studying the evolution of elemental abundances, kinematics and stellar ages in the plane of azimuthal velocity vφ and metallicity [Fe/H], we demonstrate that this metal-rich halo-like component, which we dub the Splash, is linked to the α-rich (or “thick”) disc. Splash stars have little to no angular momentum and many are on retrograde orbits. They are predominantly old, but not as old as the stars deposited into the Milky Way in the last major merger. We argue, in agreement with several recent studies, that the Splash stars may have been born in the Milky Way's proto-disc prior to the massive ancient accretion event which drastically altered their orbits. We can not, however, rule out other (alternative) formation channels. Taking advantage of the causal connection between the merger and the Splash, we put constraints of the epoch of the last massive accretion event to have finished 9.5 Gyr ago. The link between the local metal-rich and metal-poor retrograde stars is confirmed using a large suite of cutting-edge numerical simulations of the Milky Way's formation.

Citation

Grand, R. J., Evans, N. W., Deason, A. J., Smith, M. C., Fattahi, A., Sanders, J. L., & Belokurov, V. (2020). The biggest Splash. Monthly Notices of the Royal Astronomical Society, 494(3), 3880-3898. https://doi.org/10.1093/mnras/staa876

Journal Article Type Article
Acceptance Date Mar 26, 2020
Online Publication Date Apr 7, 2020
Publication Date May 31, 2020
Deposit Date Apr 8, 2020
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 494
Issue 3
Pages 3880-3898
DOI https://doi.org/10.1093/mnras/staa876

Files

Accepted Journal Article (3.9 Mb)
PDF

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2020 The Author(s) . Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






You might also like



Downloadable Citations