Collisionless Boltzmann equation approach for the study of stellar discs within barred galaxies

Bienaymé, O.

doi:10.1051/0004-6361/201731277

Cited by 2 publications

(1 citation statement)

References 49 publications

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“…10) is more consistent with our azimuthal exploration in the case of their fast-bar-only model: both data and model show an increase of strength in Hercules with positive azimuths. Bienaymé (2018) also studied the evolution of Hercules at different Galactic neighbourhoods, but in this case our range of exploration does not allow for a comparison of the key features in his simulations. In any case, further study of the Hercules structure is necessary to settle the debate about its origin and the controversy of the bar being slow or fast, first explored by (Pérez-Villegas et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Riding the kinematic waves in the Milky Way disk with Gaia

Ramos¹,

Antoja²,

Figueras³

2018

A&A

103

132

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Context. 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. Aims. Our aim is to reveal and characterize the kinematic sub-structure of the different Galactic neighbourhoods, to form a picture of their spatial evolution that can be used to infer the Galactic potential, its evolution and its components. Methods. We take ∼5 million stars in the Galactic disk from the Gaia DR2 catalogue and build the velocity distribution of many different Galactic Neighbourhoods distributed along 5 kpc in Galactic radius and azimuth. We decompose their distribution of stars in the V R -V φ plane with the wavelet transformation and asses the statistical significance of the structures found. Results. We detect many kinematic sub-structures (arches and more rounded groups) that diminish their azimuthal velocity as a function of Galactic radius in a continuous way, connecting volumes up to 3 kpc apart in some cases. The decrease rate is, on average, of ∼23 km s −1 kpc −1 . In azimuth, the kinematic sub-structures present much smaller variations. We also observe a duality in their behaviour: some conserve their vertical angular momentum with radius (e.g., Hercules), while some seem to have nearly constant kinetic energy (e.g., Sirius). These two trends are consistent with the approximate predictions of resonances and of phase mixing, respectively. Besides, the overall spatial evolution of Hercules is consistent with being related to the Outer Lindblad Resonance of the Bar. We also detect structures without apparent counterpart in the vicinity of the Sun. Conclusions. The various trends observed and their continuity with radius and azimuth allows for future work to deeply explore the parameter space of the models. Also, the characterization of extrasolar moving groups opens the opportunity to expand our understanding of the Galaxy beyond the Solar Neighbourhood.

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Section: Discussionmentioning

confidence: 99%

Riding the kinematic waves in the Milky Way disk with Gaia

Ramos¹,

Antoja²,

Figueras³

2018

A&A

103

132

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Combined dynamical effects of the bar and spiral arms in a Galaxy model. Application to the solar neighbourhood

Michtchenko

Lépine

Barros

et al. 2018

A&A

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Context. Observational data indicate that the Milky Way is a barred spiral galaxy. Computation facilities and availability of data from Galactic surveys stimulate the appearance of models of the Galactic structure, however further efforts are needed to build dynamical models containing both spiral arms and the central bar/bulge. Aims. We expand the study of the stellar dynamics in the Galaxy by adding the bar/bulge component to a model with spiral arms introduced in one of our previous publications. The model is tested by applying it to the solar neighbourhood, where observational data are more precise. Methods. We model analytically the potential of the Galaxy to derive the force field in its equatorial plane. The model comprises an axisymmetric disc derived from the observed rotation curve, four spiral arms with Gaussian-shaped groove profiles, and a classical elongated/oblate ellipsoidal bar/bulge structure. The parameters describing the bar/bulge are constrained by observations and the stellar dynamics, and their possible limits are determined. Results. A basic model results in a bar of 2.9 kpc in length, with a mass of the order of a few 10 9 M (which does not include the axisymmetric part of the bulge, which has a mass of about 10 10 M ). The size and orientation of the bar are also restricted by the position of masers with Very Long Baseline Interferometry (VLBI). The bar's rotation speed is constrained to Ω bar < 50 km s −1 kpc −1 taking into account the allowed mass range. Conclusions. We conclude that our basic model is compatible with observations and with the dynamical constraints. The model explains simultaneously the bulk of the main moving groups, associated here with the spiral corotation resonance, and the Hercules stream, associated with several inner high-order spiral resonances; in particular, with the 8/1 resonance. From the dynamical constraints on the bar's angular speed, it is unlikely that the bar's outer Lindblad resonance (OLR) lies near the solar circle; moreover, its proximity would compromise the stability of the local arm structure.

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Collisionless Boltzmann equation approach for the study of stellar discs within barred galaxies

Cited by 2 publications

References 49 publications

Riding the kinematic waves in the Milky Way disk with Gaia

Riding the kinematic waves in the Milky Way disk with Gaia

Combined dynamical effects of the bar and spiral arms in a Galaxy model. Application to the solar neighbourhood

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