The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study

Vallée, J. P.

doi:10.1086/431744

Cited by 138 publications

(158 citation statements)

References 37 publications

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“…Recent studies consider more complex models based on four spiral arms (e.g., Lépine, Mishurov & Dedikov 2001;Vallée 2016b) and their connections with the pattern of chemical properties of the MW (e.g., Lépine, Acharova & Mishurov 2003;Andrievsky et al 2004) and the not monotonic features of the MW rotation curve (e.g., . Finally, this research field has been recently boosted by numerical simulations.…”

Section: Observational Studies Of Density Wave Theorymentioning

confidence: 99%

Spiral arm kinematics for Milky Way stellar populations

Pasetto

Natale

Kawata

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a new theoretical population synthesis model (the Galaxy Model) to examine and deal with large amounts of data from surveys of the Milky Way and to decipher the present and past structure and history of our own Galaxy.We assume the Galaxy to consist of a superposition of many composite stellar populations belonging to the thin and thick disks, the stellar halo and the bulge, and to be surrounded by a single dark matter halo component. A global model for the Milky Way's gravitational potential is built up self-consistently with the density profiles from the Poisson equation. In turn, these density profiles are used to generate synthetic probability distribution functions (PDFs) for the distribution of stars in colour-magnitude diagrams (CMDs). Finally, the gravitational potential is used to constrain the stellar kinematics by means of the moment method on a (perturbed)-distribution function. Spiral arms perturb the axisymmetric disk distribution functions in the linear response framework of density-wave theory where we present an analytical formula of the so-called 'reduction factor' using Hypergeometric functions.Finally, we consider an analytical non-axisymmetric model of extinction and an algorithm based on the concept of probability distribution function to handle colour magnitude diagrams with a large number of stars. A genetic algorithm is presented to investigate both the photometric and kinematic parameter space.This galaxy model represents the natural framework to reconstruct the structure of the Milky Way from the heterogeneous data set of surveys such as Gaia-ESO, SEGUE, APOGEE2, RAVE and the Gaia mission.

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Section: Observational Studies Of Density Wave Theorymentioning

confidence: 99%

Spiral arm kinematics for Milky Way stellar populations

Pasetto

Natale

Kawata

et al. 2016

Mon. Not. R. Astron. Soc.

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“…As a basis we take the same spiral arm model as mentioned above, i.e. the model established by Vallée (2002Vallée ( , 2005, which consists of four logarithmic and symmetrically positioned arms. Around these, we take a Gaussian shape (analogous to the approach in Shaviv 2003) to yield an analytic expression for the source term Q, by summing up over all four arms (n ∈ {1, 2, 3, 4}): with r n = r 0 exp(k(ϕ + ϕ n )), where ϕ n introduces the symmetric rotation of each arm by 90 • , i.e.…”

Section: Source Distributionmentioning

confidence: 99%

Anisotropic diffusion of Galactic cosmic ray protons and their steady-state azimuthal distribution

Effenberger

Fichtner

Scherer

et al. 2012

A&A

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Galactic transport models for cosmic rays involve the diffusive motion of these particles in the interstellar medium. Owing to the large-scale structured Galactic magnetic field, this diffusion is anisotropic with respect to the local field direction. We included this transport effect along with continuous loss processes in a quantitative model of Galactic propagation for cosmic ray protons that is based on stochastic differential equations. We calculated energy spectra at different positions along the Sun's Galactic orbit and compared them to the isotropic diffusion case. The results show that a larger amplitude of variation and different spectral shapes are obtained in the introduced anisotropic diffusion scenario, which in turn emphasizes the need for accurate Galactic magnetic field models.

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“…Likewise, stars connected with a line indicate the two possible locations of star S8 in NGC 2383. We also show the path of the Outer-and Perseus-arms according to Vallée (2005) and the axis of the Local arm (long-dashed wide grey line). An angular scale is also drawn.…”

Section: The Clusters and Spiral Structurementioning

confidence: 99%

“…The Outer and Perseus arms from Vallée (2005) are drawn for the reader's guidance. In order to compare cluster locations with those of potential star formation complexes, CO clouds (open squares) with masses higher than 0.5 × 10 5 M (May et al 1997 have been plotted.…”

Section: The Clusters and Spiral Structurementioning

confidence: 99%

Open clusters in the Third Galactic Quadrant III. Alleged binary clusters

Vazquez

Moitinho

Carraro³

et al. 2010

A&A

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Aims. We aim to determine accurate distances and ages of eight open clusters in order to: (1) assess their possible binarity (2) provide probes to trace the structure of the Third Galactic Quadrant. Methods. Cluster reddenings, distances, ages and metallicities are derived from ZAMS and isochrone fits in UBVRI photometric diagrams. Field contamination is reduced by restricting analysis to stars within the cluster limits derived from star counts. Further membership control is done by requiring that stars have consistent positions in several diagrams and by using published spectral types. Results. The derived distances, ages and metallicities have shown that none of the analysed clusters compose binary/double systems. Of the four candidate pairs, only NGC 2383/NGC 2384 are close to each other, but have different metallicities and ages. Ruprecht 72 and Ruprecht 158 are not clusters but fluctuations of the field stellar density. Haffner 18 is found to be the superposition of two stellar groups at different distances: Haffner 18(1) at 4.5 kpc and Haffner 18(2) between 9.5 and 11.4 kpc from the Sun. The derived distances and ages have been used to situate the clusters in the Galactic context. In particular, young stellar groups trace spiral structure at large Galactocentric radii. At least two clusters formed during the last few 10 8 yr in an interstellar medium with less than solar abundances. Conclusions. In contrast with the LMC, double clusters are apparently rare, or even non existent, in the undisturbed environment of the Third Galactic Quadrant. This leaves open the question of whether binary clusters form more easily toward denser and more violent regions of the Milky Way such as the inner Galaxy.

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The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study

Cited by 138 publications

References 37 publications

Spiral arm kinematics for Milky Way stellar populations

Spiral arm kinematics for Milky Way stellar populations

Anisotropic diffusion of Galactic cosmic ray protons and their steady-state azimuthal distribution

Open clusters in the Third Galactic Quadrant III. Alleged binary clusters

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