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Phase-space data, chemistry, and ages together reveal a complex structure in the outer low-${\alpha}$ disc of the Milky Way. The age-vertical velocity dispersion profiles beyond the Solar Neighbourhood show a significant jump at 6 Gyr for…

星系天体物理 · 物理学 2023-05-15 Payel Das , Yang Huang , Ioana Ciuca , Francesca Fragkoudi

We present the age-velocity dispersion relation (AVR) in three dimensions in the solar neighbourhood using 3,564 commonly observed sub-giant/red-giant branch stars selected from LAMOST, which gives the age and radial velocity, and…

星系天体物理 · 物理学 2018-01-31 Jincheng Yu , Chao Liu

In this paper, we construct a detailed circular velocity curve of the Milky Way out to 20 kpc based on the radial component of the Jeans equation in cylindrical coordinates, assuming an axisymmetric gravitational potential, and show its…

RR Lyrae stars (RRLs) are tracers of the Milky Way's fossil record, holding valuable information on its formation and early evolution. Owing to the high interstellar extinction endemic to the Galactic plane, distant RRLs lying at low…

We have used N-body simulations for the Milky Way to investigate the kinematic and structural properties of the old metal-poor stellar halo in the barred inner region of the Galaxy. We find that the extrapolation of the density distribution…

星系天体物理 · 物理学 2016-10-26 Angeles Pérez-Villegas , Matthieu Portail , Ortwin Gerhard

The nature of our Milky Way Galaxy is reexamined from an eclectic point of view. Evidence for a central bar, for example, is not reflected in the distribution of RR Lyrae variables in the central bulge [4,5], and it is not clear if either a…

星系天体物理 · 物理学 2015-06-17 David G. Turner

We present results from the analysis of 401 RR Lyrae stars (RRLs) belonging to the field of the Milky Way (MW). For a fraction of them multi-band ($V$, $K_{\rm s}$, $W1$) photometry, metal abundances, extinction values and pulsation periods…

太阳与恒星天体物理 · 物理学 2018-08-22 Tatiana Muraveva , Hector E. Delgado , Gisella Clementini , Luis M. Sarro , Alessia Garofalo

Modern astrometric and spectroscopic surveys have revealed a wealth of structure in the phase space of stars in the Milky Way, with evidence of resonance features and non-equilibrium processes. Using Gaia's third data release, we present…

We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars…

星系天体物理 · 物理学 2016-04-27 Andrea Kunder , R. M. Rich , J. Storm , D. M. Nataf , R. De Propris , A. R. Walker , G. Bono , C. I. Johnson , J. Shen , Z. Y. Li

RR Lyrae stars being distance indicators and tracers of old population serve as excellent probes of the structure, formation, and evolution of our Galaxy. Thousands of them are being discovered in ongoing wide-field surveys. The OGLE…

星系天体物理 · 物理学 2016-09-07 Pawel Pietrukowicz , OGLE collaboration

We present the results of a search for short-period variable stars in Leo A. We have found 92 candidate variables, including eight candidate RR Lyrae stars. From the RR Lyraes, we measure a distance modulus of (m-M)_0 = 24.51 +/- 0.12, or…

We provide uniform RR Lyrae-based distances to 39 dwarf galaxies in and around the Local Group. We determine distances based on a Bayesian hierarchical model that uses periods and magnitudes of published RR Lyrae in dwarf galaxies and is…

星系天体物理 · 物理学 2022-06-17 Pranav Nagarajan , Daniel R. Weisz , Kareem El-Badry

We present a revised catalog of 2106 Galactic stars, selected without kinematic bias, and with available radial velocities, distance estimates, and metal abundances in the range 0.0 <= [Fe/H] <= -4.0. This update of the Beers and…

天体物理学 · 物理学 2009-10-31 T. C. Beers , M. Chiba , Y. Yoshii , I. Platais , R. B. Hanson , B. Fuchs , S. Rossi

Stellar ages are a crucial component to studying the evolution of the Milky Way. Using Gaia DR2 distance estimates, it is now possible to estimate stellar ages for a larger volume of evolved stars through isochrone matching. This work…

We use photometric metallicity estimates for about 700000 stars in the surroundings of the Sun, with very accurate distances and 3-D motions measures from Gaia DR3, to explore the properties of the metal-poor (-2.0<[Fe/H]<= -1.5; MP) and…

星系天体物理 · 物理学 2023-12-06 M. Bellazzini , D. Massari , E. Ceccarelli , A. Mucciarelli , A. Bragaglia , M. Riello , F. De Angeli , P. Montegriffo

We used Gaia DR2 data in order to estimate parameters of the Pleiades. With the data on stars with m_G<=18 mag, we constructed the density maps and profile, luminosity and mass functions, determined the cluster radius, 10.9+/-0.3 deg…

星系天体物理 · 物理学 2021-01-20 Vladimir M. Danilov , Anton F. Seleznev

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…

星系天体物理 · 物理学 2018-11-14 P. Ramos , T. Antoja , F. Figueras

Detailed elemental abundance patterns of metal-poor ([Fe/H] ~ -1~dex) stars in the Galactic bulge indicate that a number of them are consistent with globular cluster (GC) stars and may be former members of dissolved GCs. This would indicate…

We derive age-metallicity relations (AMRs) and orbital parameters for the 1658 solar neighbourhood stars to which accurate distances are measured by the HIPPARCOS satellite. The sample stars comprise 1382 thin disc stars, 229 thick disc…

天体物理学 · 物理学 2009-11-07 A. Ibukiyama , N. Arimoto