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Related papers: The Stellar Distribution Function and Local Vertic…

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A simple model is presented of the formation of the spiral the (z,v_z) phase plane of solar-neighbourhood stars that was recently discovered in Gaia data. The key is that the frequency Omega_z at which stars oscillate vertically depends on…

Astrophysics of Galaxies · Physics 2018-09-05 James Binney , Ralph Schoenrich

A new class of models of stellar discs is introduced and used to build a self-consistent model of our Galaxy. The model is defined by the parameters that specify the action-based distribution functions (DFs) f(J) of four stellar discs…

Astrophysics of Galaxies · Physics 2023-01-25 James Binney , Eugene Vasiliev

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.…

We use Gaia DR2 magnitudes, colours and parallaxes for stars with G<12 to explore a 15-dimensional space that includes simultaneously the initial mass function (IMF) and a non-parametric star formation history (SFH) for the Galactic disc.…

Astrophysics of Galaxies · Physics 2019-04-03 R. Mor , A. C. Robin , F. Figueras , S. Roca-Fàbrega , X. Luri

We investigate the structure of our Galaxy's young stellar disc by fitting the distribution functions (DFs) of a new family to five-dimensional Gaia data for a sample of $47\,000$ OB stars. Tests of the fitting procedure show that the young…

Astrophysics of Galaxies · Physics 2022-07-20 Chengdong Li , James Binney

Using the method that was developed in the first paper of this series, we measure the vertical gravitational potential of the Galactic disk from the time-varying structure of the phase-space spiral, using data from Gaia as well as…

Astrophysics of Galaxies · Physics 2021-12-01 Axel Widmark , Chervin F. P. Laporte , Pablo F. de Salas , Giacomo Monari

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

Angle/action based distribution function (DF) models can be optimised based on how well they reproduce observations thus revealing the current matter distribution in the Milky Way. Gaia data combined with data from other surveys, e.g. the…

Astrophysics of Galaxies · Physics 2018-06-13 David R Cole , James Binney

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

The Gaia DR2 radial velocity sample (GDR2RVS), which provides six-dimensional phase-space information on 7.2 million stars, is of great value for inferring properties of the Milky Way. Yet a quantitative and accurate modelling of this…

Instrumentation and Methods for Astrophysics · Physics 2020-10-28 Jan Rybizki , Hans-Walter Rix , Markus Demleitner , Coryn Bailer-Jones , William J. Cooper

The Gaia Radial Velocity Spectrometer (RVS) provides a sample of 7,224,631 stars with full six-dimensional phase space information. Bayesian distances of these stars are available from the catalogue of Sch\"onrich et al. (2019). We exploit…

Astrophysics of Galaxies · Physics 2019-08-21 A. Everall , N. W. Evans , V. Belokurov , R. Schönrich

Gaia DR2 published positions, parallaxes and proper motions for an unprecedented 1,331,909,727 sources, revolutionising the field of Galactic dynamics. We complement this data with the Astrometry Spread Function (ASF), the expected…

Astrophysics of Galaxies · Physics 2021-03-18 Andrew Everall , Douglas Boubert , Sergey E. Koposov , Leigh Smith , Berry Holl

The gravitational potential of the Milky Way encodes information about the distribution of all matter -- including dark matter -- throughout the Galaxy. Gaia data release 3 has revealed a complex structure that necessitates flexible models…

Astrophysics of Galaxies · Physics 2025-08-05 Taavet Kalda , Gregory M. Green

Matter distribution models of the Milky Way galaxy are usually stationary, although there are known to be wave-like perturbations in the disc at $\sim10\%$ level of the total density. Modelling of the overall acceleration field by allowing…

Astrophysics of Galaxies · Physics 2021-08-18 Rain Kipper , Peeter Tenjes , Elmo Tempel , Roberto de Propris

Distribution functions (DFs) for dynamically warm thin stellar disks residing in arbitrary axisymmetric potentials are presented which approximately reproduce pre-described surface-density and velocity-dispersion profiles. The functional…

Astrophysics · Physics 2009-10-31 Walter Dehnen

We estimate the Milky Way (MW) halo properties using satellite kinematic data including the latest measurements from Gaia DR2. With a simulation-based 6D phase-space distribution function (DF) of satellite kinematics, we can infer halo…

Astrophysics of Galaxies · Physics 2020-05-06 Zhao-Zhou Li , Yong-Zhong Qian , Jiaxin Han , Ting S. Li , Wenting Wang , Y. P. Jing

Analytic distribution functions (DFs) for the Galactic disc are discussed. The DFs depend on action variables and their predictions for observable quantities are explored under the assumption that the motion perpendicular to the Galactic…

Astrophysics of Galaxies · Physics 2015-05-14 James Binney

Context: With the data releases from the astrometric space mission Gaia, the exploration of the structure of the Milky Way has developed in unprecedented detail and unveiled many previously unknown structures in the Galactic disc and halo.…

Astrophysics of Galaxies · Physics 2024-07-08 S. Alinder , P. J. McMillan , T. Bensby

Gaia DR2 has provided an unprecedented wealth of information about the kinematics of stars in the Solar neighbourhood, and has highlighted the degree of features in the Galactic disc. We confront the data with a range of bar and spiral…

Astrophysics of Galaxies · Physics 2019-10-02 Jason A. S. Hunt , Mathew W. Bub , Jo Bovy , J. Ted Mackereth , Wilma H. Trick , Daisuke Kawata

We present an analysis of the kinematics of Galactic disc white dwarf stars in the Solar neighbourhood using data from Gaia Data Release 2. Selection of white dwarfs based on parallax provides the first large, kinematically unbiased sample…

Astrophysics of Galaxies · Physics 2019-01-30 Nicholas Rowell , Mukremin Kilic