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We introduce a method to infer the vertical distribution of stars in the Milky Way using a Poisson likelihood function, with a view to applying our method to the Gaia catalogue. We show how to account for the sample selection function and…

Astrophysics of Galaxies · Physics 2021-12-08 Andrew Everall , N. Wyn Evans , Vasily Belokurov , Douglas Boubert , Robert J. J. Grand

Over the past two decades observations have revealed that the vertical density distribution of stars in galaxies near the mid-plane is substantially steeper than the sech^2 function that is expected from an isothermal approximation.…

Astrophysics · Physics 2011-02-11 Arunima Banerjee , Chanda J. Jog

We present a low metallicity map of the Milky Way consisting of $\sim$111,000 giants with $-3.5 \lesssim$ [Fe/H] $\lesssim -$0.75, based on public photometry from the second data release of the SkyMapper survey. These stars extend out to…

Astrophysics of Galaxies · Physics 2021-04-28 Anirudh Chiti , Mohammad K. Mardini , Anna Frebel , Tatsuya Daniel

We apply a statistical deconvolution of the parallax errors based on Lucy's inversion method (LIM) to the Gaia-DR3 sources to measure their three dimensional velocity components in the range of Galactocentric distances $R$ between 8 kpc and…

Astrophysics of Galaxies · Physics 2023-01-04 Hai-Feng Wang , Žofia Chrobáková , Martín López-Corredoira , Francesco Sylos Labini

Classical Cepheids (CCs) are excellent tracers for understanding the structure of the Milky Way disk. The latest Gaia Data Release 3 provides a large number of line-of-sight velocity information for Galactic CCs, offering an opportunity for…

Astrophysics of Galaxies · Physics 2024-02-27 Xiaoyue Zhou , Xiaodian Chen , Licai Deng , Shu Wang

In the standard $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology, the existence of massive pure-disc galaxies remains challenging within the hierarchical framework and is key to understanding the evolutionary history of Milky Way-like…

We measure the Galactic rotation curve and its first two vertical derivatives in the first and fourth quadrants of the Milky Way using the 21 cm VGPS and SGPS. We find tangent velocities of the atomic gas as a function of galactic longitude…

Astrophysics · Physics 2009-06-23 E. S. Levine , Carl Heiles , Leo Blitz

Using N-body simulations of the Milky Way interacting with a satellite similar to the Sagittarius dwarf galaxy, we quantitatively analyse the vertical response of the Galactic disc to the satellite's repeated impacts. We approximate the…

We provide new constraints on the chemo-dynamical models of the Milky Way by measuring the radial and vertical chemical gradients for the elements Mg, Al, Si, Ti, and Fe in the Galactic disc and the gradient variations as a function of the…

The innermost regions of most galaxies are characterised by the presence of extremely dense nuclear star clusters. Nevertheless, these clusters are not the only stellar component present in galactic nuclei, where larger stellar structures…

In the central few degrees of the bulge of the Milky Way there is a flattened structure of gas, dust and stars (the central molecular zone) similar to nuclear disks in other galaxies. Due to extreme foreground extinction we possess only…

Recently, Widrow and collaborators announced the discovery of vertical density waves in the Milky Way disk. Here we investigate a scenario where these waves were induced by the Sagittarius dwarf galaxy as it plunged through the Galaxy.…

Astrophysics of Galaxies · Physics 2015-06-05 Facundo A. Gómez , Ivan Minchev , Brian W. O'Shea , Timothy C. Beers , James S. Bullock , Chris W. Purcell

We examine the outer Galactic HI disk for deviations from the b=0 plane by constructing maps of disk surface density, mean height, and thickness. We find that the Galactic warp is well described by a vertical offset plus two Fourier modes…

Astrophysics · Physics 2009-11-11 E. S. Levine , Leo Blitz , Carl Heiles

Recent spectroscopic observations in the Milky Way suggest that the chemically defined thick disk (stars with high [alpha/Fe] ratios and thus old) has a significantly smaller scale-length than the thin disk. This is in apparent…

Astrophysics of Galaxies · Physics 2015-06-24 I. Minchev , M. Martig , D. Streich , C. Scannapieco , R. S. de Jong , M. Steinmetz

Based on the Sloan Digital Sky Survey (SDSS), we develop a new monte-carlo based method to estimate the photometric metallicity distribution function (MDF) for stars in the Milky Way. Compared with other photometric calibration methods,…

Astrophysics of Galaxies · Physics 2016-07-27 Jiayin Gu , Cuihua Du , Yingjie jing , Wenbo Zuo

We created a three-dimensional distribution map of molecular gas throughout the Milky Way Galaxy using the latest $^{12}$CO($J=$1--0) survey data cube and rotation curve based on the kinematic distance. The radial distribution of the…

Astrophysics · Physics 2015-06-24 Hiroyuki Nakanishi , Yoshiaki Sofue

In local disk galaxies such as our Milky Way, older stars generally inhabit a thicker disk than their younger counterparts. Two competing models have attempted to explain this result: one in which stars first form in thin disks that…

Orbital properties of stars, computed from their six-dimensional phase space measurements and an assumed Galactic potential, are used to understand the structure and evolution of the Galaxy. Stellar actions, computed from orbits, have the…

The phase spiral is a perturbation to the vertical phase-space distribution of stars in the Milky Way disk. We study the phase spiral's properties and how they vary with spatial position, in order to constrain its origin and evolution, as…

Astrophysics of Galaxies · Physics 2025-07-29 Axel Widmark , Kiyan Tavangar , Josh Kalish , Kathryn V. Johnston , Jason A. S. Hunt

The vertical evolution of galactic discs is governed by the sub-structures within them. We examine the diversity of kinematic sub-structure present in the first 12 galaxies observed from the GECKOS survey, a VLT/MUSE large programme…