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We select 1,052,469 (754,635) thin disk stars from {\it Gaia} eDR3 and LAMOST DR7 in the range of Galactocentric radius $R$ (guiding center radius $R_\mathrm{g}$) from 8 to 11\,kpc to investigate the asymmetries between the North and South…

星系天体物理 · 物理学 2024-01-10 Jun Lin , Rui Guo , Sarah A. Bird , Haijun Tian , Chao Liu , Chris Flynn , Gaochao Liu , Sheng Cui

We examine the idea that dynamical parameters can be estimated by identifying locations in the solar neighbourhood where simulated velocity distributions match the observed local distribution. Here, the dynamical influence of both the…

天体物理学 · 物理学 2009-11-13 Dalia Chakrabarty

The third data release (DR3) of Gaia has provided a five-fold increase in the number of radial velocity measurements of stars, as well as a stark improvement in parallax and proper motion measurements. To help with studies that seek to test…

星系天体物理 · 物理学 2023-07-19 Tri Nguyen , Xiaowei Ou , Nondh Panithanpaisal , Nora Shipp , Lina Necib , Robyn Sanderson , Andrew Wetzel

Large spectroscopic and astrometric surveys have revealed complex wave-like features in the Milky Way disk, suggesting that its kinematic and chemical structures are shaped by time-dependent perturbations. Recent studies have reported…

星系天体物理 · 物理学 2026-05-08 Jifei Wang , Zhuohan Li , Chengdong Li , Yuqin Chen , Chengqun Yang , Zixi Guo , Zhou Fan , Hongrui Gu , Maoli Bu

The velocity distribution of stars is a sensitive probe of the gravitational potential of the Galaxy, and hence of its dark matter distribution. In particular, the shape of the dark halo (e.g. spherical, oblate, or prolate) determines…

星系天体物理 · 物理学 2019-09-11 Jorrit H. J. Hagen , Amina Helmi , P. Tim de Zeeuw , Lorenzo Posti

We have discovered a clear sign of the disruption phase of the Perseus arm in the Milky Way using Cepheid variables, taking advantage of the accurately measured distances of Cepheids and the proper motions from Gaia Data Release 1. Both the…

星系天体物理 · 物理学 2018-02-14 Junichi Baba , Daisuke Kawata , Noriyuki Matsunaga , Robert J. J. Grand , Jason A. S. Hunt

Local stellar motions are expected, and have been shown, to include signatures of the Galaxy's past dynamical evolution. These are typically divided into the disc, which shows the dynamical effects of spiral arms and the bar, and the…

星系天体物理 · 物理学 2022-12-26 Daniel Mikkola , Paul J. McMillan , David Hobbs

We studied 12 disk streams found in a 250$^3$ pc$^3$ volume in the solar neighborhood, which we define as coeval and comoving stellar structures with aspect ratios greater than 3:1. Using Gaia Data Release 3 data and the advanced clustering…

We perform numerical simulations of a stellar galactic disk with initial conditions chosen to represent an unrelaxed population which might have been left following a merger. Stars are unevenly distributed in radial action angle, though the…

星系天体物理 · 物理学 2009-11-13 I. Minchev , A. C. Quillen , M. Williams , K. C. Freeman , J. Nordhaus , A. Siebert , O. Bienayme

We provide a purely dynamical global map of the non-axisymmetric structure of the Milky Way disk. For this, we exploit the information contained within the in-plane motions of disk stars from Gaia DR3 to adjust a model of the Galactic…

星系天体物理 · 物理学 2025-07-16 Y. R. Khalil , B. Famaey , G. Monari , M. Bernet , A. Siebert , R. Ibata , G. F. Thomas , P. Ramos , T. Antoja , C. Li , S. Rozier , M. Romero-Gómez

Understanding the spiral arms of the Milky Way (MW) remains a key open question in galactic dynamics. Tidal perturbations, such as the recent passage of the Sagittarius dwarf galaxy (Sgr), could play a significant role in exciting them. We…

The structure and dynamics of the central bar of the Milky Way are still under debate whilst being fundamental ingredients for the evolution of our Galaxy. The recent Gaia DR3 offers an unprecedented detailed view of the 6D phase-space of…

星系天体物理 · 物理学 2024-06-05 Marcel Bernet , Pau Ramos , Teresa Antoja , Giacomo Monari , Benoit Famaey

Satellites orbiting disc galaxies can induce phase space features such as spirality, vertical heating and phase-mixing in their discs. Such features have also been observed in our own Galaxy, but the complexity of the Milky Way disc has…

星系天体物理 · 物理学 2020-03-31 Tomás Ruiz-Lara , Carme Gallart , Edouard J. Bernard , Santi Cassisi

The Sagittarius dwarf spheroidal (Sgr) is a dissolving galaxy being tidally disrupted by the Milky Way (MW). Its stellar stream still poses serious modelling challenges, which hinders our ability to use it effectively as a probe of the MW…

星系天体物理 · 物理学 2022-10-12 P. Ramos , T. Antoja , Z. Yuan , A. Arentsen , P. -A. Oria , B. Famaey , R. Ibata , C. Mateu , J. A. Carballo-Bello

We explore the interplay between in-plane and vertical dynamics in stellar discs within the framework of the shearing box approximation. Julian and Toomre used the shearing sheet to show that leading density waves are amplified as they…

星系天体物理 · 物理学 2023-04-12 Lawrence M. Widrow

The hierarchical model of galaxy formation predicts that the Milky Way halo is populated by tidal debris of dwarf galaxies and globular clusters. Due to long dynamical times, debris from the lowest mass objects remains coherent as thin and…

星系天体物理 · 物理学 2024-05-31 Ana Bonaca , Adrian M. Price-Whelan

The quality and quantity of 6D stellar position-velocity measurements in the second Gaia data release (DR2) allows to study small-scale structure in the orbit distribution of the Galactic disc beyond the immediate Solar neighborhood. We…

星系天体物理 · 物理学 2019-02-20 Wilma H. Trick , Johanna Coronado , Hans-Walter Rix

According to observations and numerical simulations, the Milky Way could exhibit several spiral arm modes with multiple pattern speeds, wherein the slower patterns are located at larger Galactocentric distances. Our aim is to quantify the…

Stellar variability studies are now reaching a completely new level thanks to ESA's Gaia mission, which enables us to locate many variable stars in the Hertzsprung-Russell diagram and determine the various instability strips/bands.…

The stellar velocity distribution in the Solar Neighbourhood displays kinematic substructures, which are possibly signatures of the bar and spiral arms of the Milky Way and of previous accretion events. These kinematic substructures --…