# On the alleged duality of the Galactic halo

```@article{Schoenrich2010OnTA,
title={On the alleged duality of the Galactic halo},
author={Ralph Schoenrich and Martin Asplund and Luca Casagrande},
journal={Monthly Notices of the Royal Astronomical Society},
year={2010},
volume={415},
pages={3807-3823}
}```
• Published 3 December 2010
• Physics
• Monthly Notices of the Royal Astronomical Society
We examine the kinematics of the Galactic halo based on SDSS/SEGUE data by Carollo et al. We find that their claims of a counter-rotating halo are the result of substantial biases in distance estimates (of the order of 50 per cent): the claimed retrograde component, which makes up only a tiny fraction of the entire sample, prone to contaminations, is identified as the tail of distance overestimates. The strong overestimates also result in a lift in the vertical velocity component, which…

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## References

SHOWING 1-10 OF 57 REFERENCES
The Case for the Dual Halo of the Milky Way
• Physics
• 2012
Carollo et al. have recently resolved the stellar population of the Milky Way halo into at least two distinct components, an inner halo and an outer halo. This result has been criticized by Schonrich
Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from Sloan Digital Sky Survey DR7
• Physics
• 2009
The structure and kinematics of the recognized stellar components of the Milky Way are explored, based on well-determined atmospheric parameters and kinematic quantities for 32360 "calibration stars"
Local kinematics and the local standard of rest
• Physics
• 2009
We re-examine the stellar kinematics of the solar neighbourhood in terms of the velocity υ� of the Sun with respect to the local standard of rest. We show that the classical determination of its
Two stellar components in the halo of the Milky Way
• Physics
Nature
• 2007
It is shown that the halo is indeed clearly divisible into two broadly overlapping structural components—an inner and an outer halo—that exhibit different spatial density profiles, stellar orbits and stellar metallicities (abundances of elements heavier than helium).
Compositions of halo clusters and the formation of the galactic halo
• Physics
• 1978
A method of abundance determination based on reddening-independent properties of low-resolution spectral scans is described and applied to 177 red giants in 19 globular clusters, most of which are at
ASSEMBLY OF THE OUTER GALACTIC STELLAR HALO IN THE HIERARCHICAL MODEL
• Physics
• 2010
We provide a set of numerical N-body simulations for studying the formation of the outer Milky Ways' stellar halo through accretion events. After simulating minor mergers of prograde and retrograde
Halo Star Streams in the Solar Neighborhood
• Physics, Geology
• 2007
We have assembled a sample of halo stars in the solar neighborhood to look for halo substructure in velocity and angular momentum space. Our sample (231 stars) includes red giants, RR Lyrae variable
Origin and structure of the Galactic disc(s)
• Physics
• 2009
We examine the chemical and dynamical structure in the solar neighbourhood of a model Galaxy that is the endpoint of a simulation of the chemical evolution of the Milky Way in the presence of radial
HALO STREAMS IN THE SEVENTH SLOAN DIGITAL SKY SURVEY DATA RELEASE
• Physics, Geology
• 2009
We have detected stellar halo streams in the solar neighborhood using data from the seventh public data release of the Sloan Digital Sky Survey (SDSS), which includes the directed stellar program
Rotation of halo populations in the Milky Way and M31
• Physics
• 2010
We search for signs of rotation in the subsystems of the Milky Way and M31 that are defined by their satellite galaxies, their globular cluster populations and their Blue Horizontal Branch (BHB)