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Related papers: The Milky Way Bar Pattern Speed using Hercules and…

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The length and pattern speed of the Milky Way bar are still controversial. Photometric and spectroscopic surveys of the inner Galaxy, as well as gas kinematics, favour a long and slowly rotating bar, with corotation around a Galactocentric…

Astrophysics of Galaxies · Physics 2017-01-18 Giacomo Monari , Daisuke Kawata , Jason A. S. Hunt , Benoit Famaey

Non-axisymmetries in the Galactic potential (spiral arms and bar) induce kinematic groups such as the Hercules stream. Assuming that Hercules is caused by the effects of the Outer Lindblad Resonance of the Galactic bar, we model…

The second data release of the Gaia mission has revealed, in stellar velocity and action space, multiple ridges, the exact origin of which is still debated. Recently, we demonstrated that a large Galactic bar with pattern speed 39 km/s/kpc…

Astrophysics of Galaxies · Physics 2019-12-11 G. Monari , B. Famaey , A. Siebert , O. Bienaymé , R. Ibata , C. Wegg , O. Gerhard

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…

Astrophysics of Galaxies · Physics 2024-06-05 Marcel Bernet , Pau Ramos , Teresa Antoja , Giacomo Monari , Benoit Famaey

It has been suggested that a resonance between a rotating bar and stars in the solar neighbourhood can produce the so called 'Hercules stream'. Recently, a second bar may have been identified in the Galactic centre, the so called 'long…

Astrophysics of Galaxies · Physics 2010-05-25 Esko Gardner , Chris Flynn

We find that a steady state bar induces transient features at low velocities in the solar neighborhood velocity distribution due to the initial response of the disc, following the formation of the bar. We associate these velocity streams…

Astrophysics of Galaxies · Physics 2015-05-14 I. Minchev , C. Boily , A. Siebert , O. Bienayme

Both the three-dimensional density of red clump giants and the gas kinematics in the inner Galaxy indicate that the pattern speed of the Galactic bar could be much lower than previously estimated. Here, we show that such slow bar models are…

Astrophysics of Galaxies · Physics 2016-12-21 Giacomo Monari , Benoit Famaey , Arnaud Siebert , Aurore Duchateau , Thibault Lorscheider , Olivier Bienaymé

We propose a novel explanation for the Hercules stream consistent with recent measurements of the extent and pattern speed of the Galactic bar. We have adapted a made-to-measure dynamical model tailored for the Milky Way to investigate the…

Astrophysics of Galaxies · Physics 2017-04-26 Angeles Pérez-Villegas , Matthieu Portail , Christopher Wegg , Ortwin Gerhard

We compare distance resolved, absolute proper motions in the Milky Way bar/bulge region to a grid of made-to-measure dynamical models with well defined pattern speeds. The data are obtained by combining the relative VVV Infrared Astrometric…

Astrophysics of Galaxies · Physics 2022-04-29 Jonathan Clarke , Ortwin Gerhard

Gaia DR2 has delivered full-sky 6-D measurements for millions of stars, and the quest to understand the dynamics of our Galaxy has entered a new phase. Our aim is to reveal and characterize the kinematic sub-structure of the different…

Astrophysics of Galaxies · Physics 2018-11-14 P. Ramos , T. Antoja , F. Figueras

We use the continuity equation to derive a method for measuring the pattern speed of the Milky Way's bar/bulge from proper motion data. The method has minimal assumptions but requires complete coverage of the non-axisymmetric component in…

Astrophysics of Galaxies · Physics 2019-08-21 Jason L. Sanders , Leigh Smith , N. Wyn Evans

The Hercules stream is a group of co-moving stars in the Solar neighbourhood, which can potentially be explained as a signature of either the outer Lindblad resonance (OLR) of a fast Galactic bar or the corotation resonance of a slower bar.…

Gaia Data Release 2 revealed detailed structures of nearby stars in phase space. These include the Hercules stream, whose origin is still debated. Most of the previous numerical studies conjectured that the observed structures originate…

Astrophysics of Galaxies · Physics 2020-09-30 Tetsuro Asano , Michiko S. Fujii , Junichi Baba , Jeroen Bédorf , Elena Sellentin , Simon Portegies Zwart

It has been proposed that the Hercules stream, a group of co-moving stars in the Solar neighborhood offset from the bulk of the velocity distribution, is the result of resonant interactions between stars in the outer disk and the Galactic…

Astrophysics of Galaxies · Physics 2010-12-01 Jo Bovy

A brief review is given of different methods used to determine the pattern speeds of the Galactic bar and spiral arms. The Galactic bar rotates rapidly, with corotation about halfway between the Galactic center and the Sun, and outer…

Astrophysics of Galaxies · Physics 2010-03-15 Ortwin Gerhard

We use low-amplitude, long period variable (LA-LPV) candidates in \textit{Gaia} DR3 to trace the kinematics and dynamics of the Milky Way bar. LA-LPVs, like other LPVs, are intrinsically bright and follow a tight period-luminosity relation,…

Astrophysics of Galaxies · Physics 2024-12-20 Hanyuan Zhang , Vasily Belokurov , N. Wyn Evans , Sarah G. Kane , Jason L. Sanders

The Milky Way (MW) hosts a central bar whose pattern speed, orientation, and length remain uncertain, largely due to observational biases and selection effects, despite the transformative data provided by the Gaia mission. We aim to…

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 --…

Astrophysics of Galaxies · Physics 2022-11-16 Marcel Bernet , Pau Ramos , Teresa Antoja , Benoit Famaey , Giacomo Monari , Hussein Al Kazwini , Mercè Romero-Gómez

There are multiple groups of comoving stars in the Solar neighbourhood, which can potentially be explained as the signatures of one of the fundamental resonances of non-axisymmetric structure such as the Galactic bar or spiral arms. One…

Astrophysics of Galaxies · Physics 2018-05-02 Jason A. S. Hunt , Jo Bovy

We provide the first quantitative evidence for the deceleration of the Galactic bar from local stellar kinematics in agreement with dynamical friction by a typical dark matter halo. The kinematic response of the stellar disk to a…

Astrophysics of Galaxies · Physics 2023-08-04 Rimpei Chiba , Jennifer K. S. Friske , Ralph Schönrich
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