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We have used N-body simulations for the Milky Way to investigate the kinematic and structural properties of the old metal-poor stellar halo in the barred inner region of the Galaxy. We find that the extrapolation of the density distribution…

Astrophysics of Galaxies · Physics 2016-10-26 Angeles Pérez-Villegas , Matthieu Portail , Ortwin Gerhard

We investigate the inner regions of the Milky Way with a sample of unprecedented size and coverage thanks to APOGEE DR16 and Gaia EDR3 data. Our inner Galactic sample has more than 26,000 stars within $|X_{\rm Gal}| <5$ kpc, $|Y_{\rm Gal}|…

We study the dynamical properties of halo stars located in the Solar Neighbourhood. Our goal is to explore how the properties of the halo depend on the selection criteria used for defining a sample of halo stars. Once this is understood we…

Astrophysics of Galaxies · Physics 2018-07-18 Lorenzo Posti , Amina Helmi , Jovan Veljanoski , Maarten Breddels

RR Lyrae stars in the Milky Way are good tracers to study the kinematic behaviour and spatial distribution of older stellar populations. A recently established well documented sample of 217 RR Lyr stars with V<12.5 mag, has been used to…

Astrophysics · Physics 2009-11-11 Gisela Maintz , Klaas S. de Boer

Large spectroscopic surveys of the Milky Way have revealed that a small population of stars in the halo have light element abundances comparable to those found in globular clusters. The favoured explanation for the peculiar abundances of…

Solar and Stellar Astrophysics · Physics 2019-04-17 A. Savino , L. Posti

[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…

Until the recent advent of $Gaia$ Data Release 2 (DR2) and deep multi-object spectroscopy, it has been difficult to obtain 6-D phase space information for large numbers of stars beyond 4 kpc, in particular towards the Galactic centre, where…

We employ Gaia DR2 proper motions for 151 Milky Way globular clusters from Vasiliev (2019) in tandem with distances and line-of-sight velocities to derive their kinematical properties. To assign clusters to the Milky Way thick disk, bulge,…

Astrophysics of Galaxies · Physics 2020-06-03 A. T. Bajkova , G. Carraro , V. I. Korchagin , N. O. Budanova , V. V. Bobylev

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

Interesting chemically peculiar field stars may reflect their stellar evolution history and their possible origin in a different environment from where they are found now, which is one of the most important research fields in Galactic…

Astrophysics of Galaxies · Physics 2020-03-11 Baitian Tang , J. G. Fernandez-Trincado , Chao Liu , Jincheng Yu , Hongliang Yan , Qi Gao , Jianrong Shi , Douglas Geisler

In this work, we derive systemic velocities and subsequently orbits for 8456 RR~Lyrae stars. We identify interlopers from other Milky Way (MW) structures, which amount to 22 percent of the total sample. Most interlopers are associated with…

We developed a new selection method of halo stars in the phase-space distribution defined by the three integrals of motion in an axisymmetric Galactic potential, ($E$, $L_z$, $I_3$), where $I_3$ is the third integral of motion. The method…

Astrophysics of Galaxies · Physics 2021-03-03 Daniela Carollo , Masashi Chiba

Globular clusters (GCs) are the most ancient stellar systems in the Milky Way. Therefore, they play a key role in the understanding of the early chemical and dynamical evolution of our Galaxy. Around $40\%$ of them are placed within $\sim4$…

Astrophysics of Galaxies · Physics 2020-01-08 Angeles Pérez-Villegas , Beatriz Barbuy , Leandro Kerber , Sergio Ortolani , Stefano O. Souza , Eduardo Bica

The fastest moving stars provide insight into several fundamental properties of the Galaxy, including the escape velocity as a function of Galactocentric radius, the total mass, and the nature and frequency of stellar encounters with the…

Solar and Stellar Astrophysics · Physics 2018-09-05 Keith Hawkins , Rosemary F. G. Wyse

The latest edition of the APOGEE-2/DR14 survey catalogue and the first \texttt{Payne} data release of APOGEE abundance determinations by Ting et al. are examined. We identify 31 previously unremarked metal-poor giant stars with anomalously…

We derive new constraints on the mass of the Milky Way's dark matter halo, based on a set of halo stars from SDSS as kinematic tracers. Our sample comprises 2401 rigorously selected Blue Horizontal-Branch (BHB) halo stars drawn from SDSS…

The Gaia mission has provided the largest ever astrometric chart of the Milky Way. Using it to map the Galactic halo is helpful for disentangling its merger history. The identification of halo stars in Gaia DR2 with reliable distance…

Astrophysics of Galaxies · Physics 2021-11-25 Helmer H. Koppelman , Amina Helmi

The origin of the high-alpha component of the Galactic bulge remains debated, unlike the bar-driven origin of the low-alpha bulge. We examine the metallicity-dependent dynamical properties of high-[Mg/Fe] stars in the bar region, using…

Astrophysics of Galaxies · Physics 2025-09-19 Aakash Pandey , Ortwin Gerhard

We construct a model for the Milky Way Galaxy composed of a stellar disc and bulge embedded in a dark-matter halo. All components are modelled as $N$-body systems with up to 8 billion equal-mass particles and integrated up to an age of…

Astrophysics of Galaxies · Physics 2018-10-17 Michiko S. Fujii , Jeroen Bédorf , Junichi Baba , Simon Portegies Zwart

We investigate the rotation curve of the Milky Way using a multi-component mass model including a stellar disk, a gaseous disk, a bulge/bar component, and a dark-matter halo. The stellar and gas contributions are calibrated using recent…

Astrophysics of Galaxies · Physics 2026-03-17 Zi Liu
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