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} }
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…
Figures and Tables from this paper
82 Citations
Does SEGUE/SDSS indicate a dual galactic halo?
- Physics
- 2014
We re-examine recent claims of observational evidence for a dual Galactic halo in SEGUE/SDSS data, and trace them back to improper error treatment and neglect of selection effects. In particular, the…
The age of the halo as determined from halo field stars
- Physics
- 2016
The age of the Galactic halo is a critical parameter that can constrain the origin of the stellar halo. In general, the Galactic stellar halo is believed to be very old. However, different…
The Fractions of Inner- and Outer-Halo Stars in the Local Volume
- Physics
- 2015
We obtain a new determination of the metallicity distribution function (MDF) of stars within $\sim5$-$10$ kpc of the Sun, based on recently improved co-adds of $ugriz$ photometry for Stripe 82 from…
The tilt of the velocity ellipsoid in the Milky Way disc
- Physics
- 2015
Accurate determination of the local dark matter density is important for understanding the nature and distribution of dark matter in the universe. This requires that the local velocity distribution…
Galactic googly: the rotation-metallicity bias in the inner stellar halo of the Milky Way
- Physics
- 2017
The first and second moments of stellar velocities encode important information about the formation history of the Galactic halo. However, due to the lack of tangential motion and inaccurate…
The detection and treatment of distance errors in kinematic analyses of stars
- Physics
- 2011
We present a new method for detecting and correcting systematic errors in the distances to stars when both proper motions and line-of-sight velocities are available. The method, which is applicable…
Rotational signature of the Milky Way stellar halo
- Physics
- 2013
We measure the rotation of the Milky Way stellar halo on two samples of Blue Horizontal Branch (BHB) field halo stars from the Sloan Digital Sky Survey (SDSS) with four different methods. The two…
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…
Weighing the stellar constituents of the galactic halo with APOGEE red giant stars
- Physics, GeologyMonthly Notices of the Royal Astronomical Society
- 2020
The stellar mass in the halo of the Milky Way is notoriously difficult to determine, owing to the paucity of its stars in the solar neighbourhood. With tentative evidence from Gaia that the nearby…
A two-point correlation function for Galactic halo stars
- Physics
- 2010
We describe a correlation function statistic that quantifies the amount of spatial and kinematic substructure in the stellar halo. We test this statistic using model stellar halo realizations…
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
- PhysicsNature
- 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)…