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We characterize the kinematic and chemical properties of 589 Galactic Anticenter Substructure Stars (GASS) with K-/M- giants in Integrals-of-Motion space. These stars likely include members of previously identified substructures such as…

The radial number density and flattening of the Milky Way's stellar halo is measured with $\mathrm{5351}$ metal-poor ([Fe/H]$<-1$) K giants from LAMOST DR3, using a nonparametric method which is model independent and largely avoids the…

We characterise the radial density, metallicity and flattening profile of the Milky Way's stellar halo, based on the large sample of 1757 spectroscopically confirmed giant stars from SDSS/SEGUE-2 after excising stars that were…

Astrophysics of Galaxies · Physics 2015-08-26 Xiang-Xiang Xue , Hans-Walter Rix , Zhibo Ma , Heather Morrison , Jo Bovy , Branimir Sesar , William Janesh

We present a new algorithm for identifying dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension,…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-15 Peter S. Behroozi , Risa H. Wechsler , Hao-Yi Wu

The latest results of the QUEST survey for RR Lyrae stars are described. This survey, which is designed to find and characterize sub-structures in the halo of our Galaxy, has covered about 700 square degrees of the sky and has detected 693…

Astrophysics · Physics 2007-05-23 A. Katherina Vivas , R. Zinn , Y. Subero , J. Hernandez

We assemble 121 spectroscopically-confirmed halo carbon stars, drawn from the literature, exhibiting measurable variability in the Catalina Surveys. We present their periods and amplitudes, which are used to estimate distances from…

Astrophysics of Galaxies · Physics 2015-09-16 Avon Huxor , Eva Grebel

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…

In order to construct a catalogue of oxygen-rich (noted M) asymptotic giant branch (AGB) stars in the halo, complementing those of carbon-rich (C) stars, previous lists of Miras and SRa semiregulars located in the nor thern hemisphere are…

Astrophysics of Galaxies · Physics 2019-06-26 Nicolas Mauron , Luc P. A. Maurin , Tim R. Kendall

We report the detection of spatially distinct stellar density features near the apocenters of the Sagittarius (Sgr) stream's main leading and trailing arm. These features are clearly visible in a high-fidelity stellar halo map that is based…

Astrophysics of Galaxies · Physics 2017-08-02 Branimir Sesar , Nina Hernitschek , Marion I. P. Dierickx , Mark A. Fardal , Hans-Walter Rix

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 distances of the halo stars, the velocity moments…

We derive a star catalogue generated from the images taken as part of the 37.5 sq. deg Millennium Galaxy Catalogue. These data, alone and together with colours gained from the Sloan Digital Sky Survey Early Data Release, allow the analysis…

Astrophysics · Physics 2009-11-10 David Lemon , Rosemary F. G. Wyse , Jochen Liske , Simon Driver , Keith Horne

The Galactic halo is supposed to form from merging with nearby dwarf galaxies. In order to probe different components of the Galactic halo, we have applied the Gaussian Mixture Models method to a selected sample of metal poor stars with…

Astrophysics of Galaxies · Physics 2021-06-23 Xilong Liang , Yuqin Chen , Jingkun Zhao , Gang Zhao

A catalog of more than 43,000 M giant stars has been selected by Li et al. from the ninth data release of LAMOST. Using the data-driven method SLAM, we obtain the stellar parameters (Teff, logg, [M/H], [$\alpha$/M]) for all the M giant…

Solar and Stellar Astrophysics · Physics 2023-05-03 Dan Qiu , Hao Tian , Jing Li , Chao Liu , Lin Long , Jian-Rong Shi , Ming Yang , Bo Zhang

Aims. Several kinematic and chemical substructures have been recently found amongst Milky Way halo stars with retrograde motions. It is currently unclear how these various structures are related to each other. This Letter aims to shed light…

Astrophysics of Galaxies · Physics 2019-11-13 Helmer H. Koppelman , Amina Helmi , Davide Massari , Adrian M. Price-Whelan , Tjitske K. Starkenburg

We use extensive gravity-sensitive DDO 51 photometry over 5100 square degrees, combined with SDSS broadband photometry, to select a catalog of $\sim 4,000$ giant stars covering a large fraction of the high Galactic latitude sky and reaching…

Astrophysics of Galaxies · Physics 2016-12-14 Colin T. Slater , David L. Nidever , Jeffrey A. Munn , Eric F. Bell , Steven R. Majewski

It has been recently shown that the halo near the Sun contains several kinematic substructures associated to past accretion events. For the more distant halo, there is evidence of large-scale density variations -- in the form of stellar…

Astrophysics of Galaxies · Physics 2021-10-04 E. Balbinot , A. Helmi

As part of the Spaghetti Project Survey (SPS) we have detected a concentration of giant stars well above expectations for a smooth halo model. The position (l~350, b~50) and distance (~50 kpc) of this concentration match those of the…

[Abridged] We present a medium-resolution spectroscopic survey of late-type giant stars at mid-Galactic latitudes of (30$^{\circ}<|b|<60^{\circ}$), designed to probe the properties of this population to distances of $\sim$9 kpc. Because M…

We describe a major survey of the Milky Way halo designed to test for kinematic substructure caused by destruction of accreted satellites. We use the Washington photometric system to identify halo stars efficiently for spectroscopic…