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Context. Gas within a galaxy is forced to establish pressure balance against gravitational forces. The shape of an unperturbed gaseous disk can be used to constrain dark matter models. Aims. We derive the 3-D HI volume density distribution…

天体物理学 · 物理学 2009-11-13 P. M. W. Kalberla , L. Dedes , J. Kerp , U. Haud

CONTEXT. The Gaia Collaboration has used Gaia-DR2 sources with six-dimensional (6D) phase space information to derive kinematical maps within 5 kpc of the Sun, which is a reachable range for stars with relative error in distance lower than…

星系天体物理 · 物理学 2019-01-09 M. Lopez-Corredoira , F. Sylos Labini

We measure the enclosed Milky Way mass profile to Galactocentric distances of $\sim70$ and $\sim50$ kpc using the smooth, diffuse stellar halo samples of Bird et al. The samples are LAMOST and SDSS/SEGUE K giants (KG) and SDSS/SEGUE blue…

We study the shape of the thick disc using photometric data at high and intermediate latitudes from SDSS and 2MASS surveys. We use the population synthesis approach using an ABC-MCMC method to characterize the thick disc shape, scale…

星系天体物理 · 物理学 2014-09-10 A. C. Robin , C. Reyle , J. Fliri , M. Czekaj , C. P. Robert , A. M. M. Martins

We study the correlation of orbital poles of the 11 classical satellite galaxies of the Milky Way, comparing results from previous proper motions with the independent data by Gaia DR2. Previous results on the degree of correlation and its…

星系天体物理 · 物理学 2020-01-08 Marcel S. Pawlowski , Pavel Kroupa

Aims. We explore the outer Galactic disc up to a Galactocentric distance of 30 kpc to derive its parameters and measure the magnitude of its flare. Methods. We obtained the 3D density of stars of type F8V-G5V with a colour selection from…

星系天体物理 · 物理学 2014-09-05 M. Lopez-Corredoira , J. Molgo

We apply Noether's theorem to observations of main-sequence stars from the Gaia Data Release 2 archive to probe the matter distribution function of the Galaxy. That is, we examine the axial symmetry of stars at vertical heights $z$, $0.2…

星系天体物理 · 物理学 2020-03-23 Susan Gardner , Austin Hinkel , Brian Yanny

We present an exploration of the Milky Way's structural parameters using an all-sky sample of RC giants to map the stellar density from the Galactic disc beyond 3 kpc. These evolved giants are considered to be standard candles due to their…

The Apache Point Observatory Galactic Evolution Experiment has measured the stellar velocities of red giant stars in the inner Milky Way. We confirm that the line of sight velocity distributions (LOSVDs) in the mid-plane exhibit a second…

星系天体物理 · 物理学 2015-10-15 Victor P. Debattista , Melissa Ness , Samuel W. F. Earp , David R. Cole

The Milky Way is a barred spiral galaxy, with physical properties inferred from various tracers informed by the extrapolation of structures seen in other galaxies. However, the distances of these tracers are measured indirectly and are…

We quantify the inside-out growth of the Milky Way's low-alpha stellar disk, modelling the ages, metallicities and Galactocentric radii of APOGEE red clump stars with 6 < R < 13 kpc. The current stellar distribution differs significantly…

星系天体物理 · 物理学 2019-11-06 Neige Frankel , Jason Sanders , Hans-Walter Rix , Yuan-Sen Ting , Melissa Ness

The mass of the Milky Way is a critical quantity which, despite decades of research, remains uncertain within a factor of two. Until recently, most studies have used dynamical tracers in the inner regions of the halo, relying on…

Nearly 400 Tycho-2 stars have been observed in a 720 square degree field in the direction of the North Galactic Pole with the high resolution echelle spectrograph ELODIE. Absolute magnitudes, effective temperatures, gravities and…

天体物理学 · 物理学 2009-11-07 C. Soubiran , O. Bienaymé , A. Siebert

We perform analysis of the three-dimensional kinematics of Milky Way disk stars in mono-age populations. We focus on stars between Galactocentric distances of $R=6$ and 14 \,kpc, selected from the combined LAMOST DR4 red clump giant stars…

In an effort to more precisely define the spatial distribution of Galactic field stars, we present an analysis of the photometric parallaxes of 70,000 stars covering nearly 15 square degrees in seven Kapteyn Selected Areas. We address the…

天体物理学 · 物理学 2009-11-07 M. H. Siegel , S. R. Majewski , I. N. Reid , I. B. Thompson

A simple model for the evolution of disc galaxies is presented. We adopt three numbers from observations of the Milky Way disc, the local surface mass density, the stellar scale length (of the assumedly exponential disc) and the amplitude…

天体物理学 · 物理学 2009-11-11 Thorsten Naab , Jeremiah P. Ostriker

The separation of the Milky Way disk into a thin and thick component is supported by differences in the spatial, kinematic and metallicity distributions of their stars. These differences have led to the view that the thick disk formed early…

星系天体物理 · 物理学 2015-05-20 Sarah R. Loebman , Rok Roskar , Victor P. Debattista , Zeljko Ivezic , Thomas R. Quinn , James Wadsley

Throughout the Milky Way, molecular clouds typically appear filamentary, and mounting evidence indicates that this morphology plays an important role in star formation. What is not known is to what extent the dense filaments most closely…

The warp is a well-known undulation of the Milky Way disc. Its structure has been widely studied, but only since Gaia DR2 has it been possible to reveal its kinematic signature beyond the solar neighbourhood. In this work we present an…

Available proper motion measurements of Milky Way (MW) satellite galaxies are used to calculate their orbital poles and projected uncertainties. These are compared to a set of recent cold dark-matter (CDM) simulations, tailored specifically…

天体物理学 · 物理学 2009-11-13 Manuel Metz , Pavel Kroupa , Noam I. Libeskind