SIMBAD references

2019MNRAS.486..378L - Mon. Not. R. Astron. Soc., 486, 378-389 (2019/June-2)

The halo's ancient metal-rich progenitor revealed with BHB stars.


Abstract (from CDS):

Using the data from the Sloan Digital Sky Survey and the Gaia satellite, we assemble a pure sample of ∼3000 blue horizontal branch (BHB) stars with 7D information, including positions, velocities, and metallicities. We demonstrate that, as traced with BHBs, the Milky Way's stellar halo is largely unmixed and cannot be well represented with a conventional Gaussian velocity distribution. A single-component model fails because the inner portions of the halo are swamped with metal-rich tidal debris from an ancient, head-on collision, known as the 'Gaia Sausage'. Motivated by the data, we build a flexible mixture model that allows us to track the evolution of the halo make-up across a wide range of radii. It is built from two components, one representing the radially anisotropic Sausage stars with their lobed velocity distribution, and the other representing a more metal-poor and more isotropic component built up from minor mergers. We show that inside 25 kpc the 'Sausage' contributes at least 50 per cent of the Galactic halo. The fraction of 'Sausage' stars diminishes sharply beyond 30 kpc, which is the long-established break radius of the classical stellar halo.

Abstract Copyright: © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): Galaxy: formation - Galaxy: halo - Galaxy: kinematics and dynamics

VizieR on-line data: <Available at CDS (J/MNRAS/486/378): bhball.dat bhbfilt.dat>

Simbad objects: 3682

goto Full paper

goto View the references in ADS

To bookmark this query, right click on this link: simbad:2019MNRAS.486..378L and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact