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Related papers: Quantifying Kinematic Substructure in the Milky Wa…

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We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13,000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of…

Astrophysics of Galaxies · Physics 2019-07-31 Chengqun Yang , Xiang-Xiang Xue , Jing Li , Lan Zhang , Chao Liu , Gang Zhao , Jiang Chang , Hao Tian , Chengdong Li

We use numerical simulations to examine the substructure within galactic and cluster mass halos that form within a hierarchical universe. Clusters are easily reproduced with a steep mass spectrum of thousands of substructure clumps that…

We present evidence for eight new clumps of blue horizontal branch (BHB) stars discovered in a catalogue of these stars compiled from the Sloan Digital Sky Survey (SDSS) by Sirko et al. published in 2004. Clumps are identified by selecting…

Astrophysics · Physics 2009-10-08 L. Clewley , T. D. Kinman

Aims: Develop a data-driven and statistically based method for finding such clumps in Integrals of Motion space for nearby halo stars and evaluating their significance robustly. Methods: We use data from Gaia EDR3 extended with radial…

Astrophysics of Galaxies · Physics 2022-09-14 S. Sofie Lövdal , Tomás Ruiz-Lara , Helmer H. Koppelman , Tadafumi Matsuno , Emma Dodd , Amina Helmi

We investigate the structure of the Milky Way's stellar halo within 70 kpc of the Sun using a wide-field photometric catalog obtained from the Hyper Suprime-Cam (HSC) Subaru Strategic Program (HSC-SSP). We employ a large sample of…

Astrophysics of Galaxies · Physics 2026-04-14 Yoshihisa Suzuki , Masashi Chiba , Rosemary F. G. Wyse , Shunichi Horigome

We study blue horizontal branch (BHB) and RR Lyrae stars in the Rogers et al. (1993a) fields and compare their velocity and density distributions with other surveys in the same part of the sky. Photometric data are given for 176 early-type…

Astrophysics of Galaxies · Physics 2015-05-27 T. D. Kinman , Warren R. Brown

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r<20 and proper-motion measurements derived from SDSS and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS…

Astrophysics of Galaxies · Physics 2014-11-20 N. A. Bond , Z. Ivezic , B. Sesar , M. Juric , J. Munn

We study the formation of the Milky Way's halo in a $\Lambda$CDM cosmology by scaling down a high resolution simulation of the formation of a cluster of galaxies. We determine how much phase-space substructure is left over from the objects…

Astrophysics · Physics 2009-09-25 Amina Helmi , Simon D. M. White , Volker Springel

Aims: we studied the global distribution and kinematics of the extra-planar neutral gas in the Milky Way. Methods: we built 3D models for a series of Galactic HI layers, projected them for an inside view, and compared them with the…

Astrophysics of Galaxies · Physics 2015-05-20 Antonino Marasco , Filippo Fraternali

We carry out a maximum-likelihood kinematic analysis of a sample of 1170 blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey presented in Sirko et al. (2003) (Paper I). Monte Carlo simulations and resampling show that the…

We have used data from the Sloan Digital Sky Survey (SDSS) Data Release 5 to explore the overall structure and substructure of the stellar halo of the Milky Way using about 4 million color-selected main sequence turn-off stars. We fit…

We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300 deg^2 of the sky. We identify 655 BHB stars in this non-kinematically selected sample. We calculate the luminosity…

Tidal debris from infalling satellites can leave observable structure in the phase-space distribution of the Galactic halo. Such substructure can be manifest in the spatial and/or velocity distributions of the stars in the halo. This paper…

Astrophysics of Galaxies · Physics 2015-06-15 Mariangela Lisanti , David N. Spergel , Piero Madau

In recent years surveys have identified several dozen B stars in the Milky Way halo moving faster than the local escape speed. The origin of most of these hypervelocity stars (HVSs) is still poorly constrained. Here we show that the…

Astrophysics of Galaxies · Physics 2023-01-02 Aleksey Generozov , Hagai B. Perets

The distribution of Milky Way halo blue horizontal-branch (BHB) stars is examined using action-based extended distribution functions (EDFs) that describe the locations of stars in phase space, metallicity, and age. The parameters of the…

Astrophysics of Galaxies · Physics 2016-08-29 Payel Das , Angus Williams , James Binney

Halo stars orbit within the potential of the Milky Way and hence their kinematics can be used to understand the underlying mass distribution. However, the inferred mass distribution depends sensitively upon assumptions made on the density…

Astrophysics of Galaxies · Physics 2015-06-22 Prajwal R. Kafle , Sanjib Sharma , Geraint F. Lewis , Joss Bland-Hawthorn

We have used RR Lyrae and Blue HB stars as tracers of the old Galactic halo, in order to study the halo structure and the galactic rotation as a function of height above the plane. Our sample includes 40 RR Lyrae and 80 BHB stars that are…

Astrophysics · Physics 2007-05-23 T. D. Kinman , A. Bragaglia , C. Cacciari , A. Buzzoni , A. Spagna

The halo stars on highly radial orbits should inevitably pass the center regions of the Milky Way. Under the assumption that the stellar halo is in dynamical equilibrium and axisymmetric, we integrate the orbits of $\sim 10,000$ halo…

Astrophysics of Galaxies · Physics 2022-11-16 Chengqun Yang , Ling Zhu , Behzad Tahmasebzadeh , Xiang-Xiang Xue , Chao Liu

We present the stellar density profile of the outer halo of the Galaxy traced over a range of Galactocentric radii from $15< R_{GC} < 220$ kpc by blue horizontal branch (BHB) stars. These stars are identified photometrically using deep…

We have measured the amount of kinematic substructure in the Galactic halo using the final data set from the Spaghetti project, a pencil-beam high latitude sky survey. Our sample contains 101 photometrically selected and spectroscopically…