The biggest splash
By V. Belokurov, J. Sanders, Azadeh Fattahi, Martin C. Smith, A. Deason, N. Evans II, R. Grand. Monthly notices of the Royal Astronomical Society, 2019
143 citations recorded by the source corpus.
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 neighbourhood, 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 (MW) in the last major merger. We argue, in agreement with several recent studies, that the Splash stars may have been born in the MW’s protodisc prior to the massive ancient accretion event which drastically altered their orbits. We cannot, 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 MW’s formation.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/9c907b730a4b54bf8d3ea42a8e4566d7cc36889b
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Citations in the corpus
- Evidence from the H3 Survey That the Stellar Halo Is Entirely Comprised of Substructure (2020, background): “…2017; Haywood et al. 2018; Di Matteo et al. 2019; Amarante et al. 2020; Belokurov et al. 2020), we find the high-α disk and its heated high-eccentricity tail (referred to as the “in situ halo” in this work and “Splash” in Belokurov et al. 2020) contribute the majority of stars at ∣ ∣ »Z 2 kpcgal .”