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Two major accretion epochs in M31 from two distinct populations of globular clusters
Dougal Mackey, Geraint F. Lewis, Brendon J. Brewer +12
Large galaxies grow through the accumulation of dwarf galaxies. In principle it is possible to trace this growth history using the properties of a galaxy's stellar halo. Previous i…
The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
Amina Helmi, Carine Babusiaux, Helmer H. Koppelman +3
The assembly process of our Galaxy can be retrieved using the motions and chemistry of individual stars. Chemo-dynamical studies of the nearby halo have long hinted at the presence…
Gaia Data Release 2. Summary of the contents and survey properties
Gaia Collaboration, A. G. A. Brown, A. Vallenari +4
We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources…
Gaia Data Release 2: Catalogue validation
F. Arenou, X. Luri, C. Babusiaux +36
The second Gaia data release (DR2), contains very precise astrometric and photometric properties for more than one billion sources, astrophysical parameters for dozens of millions,…
Scratching the surface with TGAS and RAVE: disk moving groups in the Solar neighborhood
Helmer H. Koppelman, Titania Virginiflosia, Lorenzo Posti +2
There is long tradition extending more than a century on the identification of moving groups in the Solar neighborhood. However, with the advent of large kinematic surveys, and esp…
Flavours in the box of chocolates: chemical abundances of kinematic substructures in the nearby stellar halo
Jovan Veljanoski, Amina Helmi
Stellar halos contain tracers of the assembly history of massive galaxies like our own. Exploiting the synergy between the TGAS and the spectroscopic RAVE surveys, Helmi et al. (20…
Leaves on trees: identifying halo stars with extreme gradient boosted trees
Jovan Veljanoski, Amina Helmi, Maarten Breddels +1
Extended stellar haloes are a natural by-product of the hierarchical formation of massive galaxies. If merging is a non-negligible factor in the growth of our Galaxy, evidence of s…
One large blob and many streams frosting the nearby stellar halo in Gaia DR2
Helmer H. Koppelman, Amina Helmi, Jovan Veljanoski
We explore the phase-space structure of nearby halo stars identified kinematically from Gaia DR2 data. We focus on their distribution in velocity and in "integrals of motion" space…
The dynamically selected stellar halo of the Galaxy with Gaia and the tilt of the velocity ellipsoid
Lorenzo Posti, Amina Helmi, Jovan Veljanoski +1
We study the dynamical properties of halo stars located in the Solar Neighbourhood. Our goal is to explore how the properties of the halo depend on the selection criteria used for…
A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
Amina Helmi, Jovan Veljanoski, Maarten A. Breddels +2
The hierarchical structure formation model predicts that stellar halos should form, at least partly, via mergers. If this was a predominant formation channel for the Milky Way's ha…
The kinematics of globular clusters systems in the outer halos of the Aquarius simulations
Jovan Veljanoski, Amina Helmi
Stellar halos and globular cluster (GC) systems contain valuable information regarding the assembly history of their host galaxies. Motivated by the detection of a significant rota…
The Globular Cluster System of NGC 6822
J. Veljanoski, A. M. N. Ferguson, A. D. Mackey +11
We present a comprehensive analysis of the globular cluster (GC) system of the Local Group dwarf irregular galaxy NGC 6822. Our study is based on homogeneous optical and near-IR ph…
Accretion in action: phase space coherence of stellar debris and globular clusters in Andromeda's South-West Cloud
Dougal Mackey, Geraint Lewis, Michelle Collins +13
A central tenet of the current cosmological paradigm is that galaxies grow over time through the accretion of smaller systems. Here, we present new kinematic measurements near the…
The outer halo globular cluster system of M31 - II. Kinematics
J. Veljanoski, A. D. Mackey, A. M. N. Ferguson +13
We present a detailed kinematic analysis of the outer halo globular cluster (GC) system of M31. Our basis for this is a set of new spectroscopic observations for 78 clusters lying…
The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
A. P. Huxor, A. D. Mackey, A. M. N. Ferguson +8
We report the discovery of 59 globular clusters (GCs) and two candidate GCs in a search of the halo of M31, primarily via visual inspection of CHFT/MegaCam imagery from the Pan-And…
Major Substructure in the M31 Outer Halo: the South-West Cloud
N. F. Bate, A. R. Conn, B. McMonigal +11
We undertake the first detailed analysis of the stellar population and spatial properties of a diffuse substructure in the outer halo of M31. The South-West Cloud lies at a project…
Kinematics of Outer Halo Globular Clusters in M31
J. Veljanoski, A. M. N. Ferguson, A. D. Mackey +12
We present the first kinematic analysis of the far outer halo globular cluster (GC) population in the Local Group galaxy M31. Our sample contains 53 objects with projected radii of…
Young accreted globular clusters in the outer halo of M31
A. D. Mackey, A. P. Huxor, A. M. N. Ferguson +6
We report on Gemini/GMOS observations of two newly discovered globular clusters in the outskirts of M31. These objects, PAndAS-7 and PAndAS-8, lie at a galactocentric radius of ~87…