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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. Short-timescale variability processing and analysis
M. Roelens, L. Eyer, N. Mowlavi +13
The Gaia DR2 sample of short-timescale variable candidates results from the investigation of the first 22 months of Gaia photometry for a subsample of sources at the Gaia faint end…
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,…
Gaia Data Release 2: Properties and validation of the radial velocities
D. Katz, P. Sartoretti, M. Cropper +51
For Gaia DR2 (GDR2), 280 million spectra, collected by the RVS instrument on-board Gaia, were processed and median radial velocities were derived for 9.8 million sources brighter t…
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…
Gaia Data Release 2: Photometric content and validation
D. W. Evans, M. Riello, F. De Angeli +9
Aims. We describe the photometric content of the second data release of the Gaia project (Gaia DR2) and its validation along with the quality of the data. Methods. The validation w…
Vaex: Big Data exploration in the era of Gaia
Maarten A. Breddels, Jovan Veljanoski
We present a new Python library called vaex, to handle extremely large tabular datasets, such as astronomical catalogues like the Gaia catalogue, N-body simulations or any other re…