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Pattern speed evolution of barred galaxies in TNG50
Marcin Semczuk, Walter Dehnen, Ralph Schönrich +1
Galactic bars are found in the majority of disc galaxies. They rotate nearly rigidly with an angular frequency called pattern speed. Previous idealised simulations have shown that…
Age-morphology dependence of the Milky Way boxy/peanut bulge seen in Mira variables
Marcin Semczuk, Walter Dehnen, Ralph Schoenrich +1
We analyse the distribution of Mira variable stars in the central region of the Milky Way. We find that with increasing period, i.e. decreasing age, the Miras shift towards negativ…
Tree-ring structure of Galactic bar resonance
Rimpei Chiba, Ralph Schönrich
Galaxy models have long predicted that galactic bars slow down by losing angular momentum to their postulated dark haloes. When the bar slows down, resonance sweeps radially outwar…
More than just a wrinkle: A wave-like pattern in radial velocity vs. angular momentum from Gaia Data
Jennifer Friske, Ralph Schönrich
We present a newly found wave--like pattern in mean Galactocentric radial velocity U_g vs. guiding centre radius R_g or angular momentum L_z of stars in the RV subsample of Gaia DR…
Warp, Waves, and Wrinkles in the Milky Way
Ralph Schönrich, Walter Dehnen
We derive unbiased distance estimates for the Gaia-TGAS dataset by correcting for the bias due to the distance dependence of the selection function, which we measure directly from…
Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)
V. Silva Aguirre, M. Bojsen-Hansen, D. Slumstrup +22
Investigations of the origin and evolution of the Milky Way disk have long relied on chemical and kinematic identification of its components to reconstruct our Galactic past. Diffi…
The Thirteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey MApping Nearby Galaxies at Apache Point Observatory
SDSS Collaboration, Franco D. Albareti, Carlos Allende Prieto +335
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2, MaNGA, and eBOSS. In addition, eBOSS cont…
Understanding inverse metallicity gradients in galactic discs as a consequence of inside-out formation
Ralph Schönrich, Paul McMillan
The early stages of a galaxy's evolution leave an imprint on its metallicity distribution. We discuss the origins and evolution of radial metallicity gradients in discs of spiral g…
Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models
Brett H. Andrews, David H. Weinberg, Ralph Schönrich +1
Chemical evolution models are powerful tools for interpreting stellar abundance surveys and understanding galaxy evolution. However, their predictions depend heavily on the treatme…
Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA
L. Casagrande, V. Silva Aguirre, K. J. Schlesinger +10
The existence of a vertical age gradient in the Milky Way disc has been indirectly known for long. Here, we measure it directly for the first time with seismic ages, using red gian…
Kinematic Detection of the Galactic Nuclear Disc
Ralph Schönrich, Michael Aumer, Stuart E. Sale
We report the detection of the Galactic nuclear disc in line-of-sight kinematics of stars, measured with infrared spectroscopy from APOGEE. This stellar component of the nuclear di…
Origin of the high v_los feature in the Galactic bar
Michael Aumer, Ralph Schönrich
We analyse a controlled N-body + smoothed particle hydrodynamics simulation of a growing disc galaxy within a non-growing, live dark halo. The disc is continuously fed with gas and…
Rotational signature of the Milky Way stellar halo
Francesco Fermani, Ralph Schönrich
We measure the rotation of the Milky Way stellar halo on two samples of Blue Horizontal Branch (BHB) field halo stars from the Sloan Digital Sky Survey (SDSS) with four different m…
A new calibration for the Blue Horizontal Branch
Francesco Fermani, Ralph Schönrich
We suggest a simple analytic approximation for magnitudes and hence distances of Blue Horizontal Branch (BHB) stars in Sloan colours. Precedent formulations do not offer a simple c…
Metallicity Gradients in the Milky Way Disk as Observed by the SEGUE Survey
Judy Y. Cheng, Constance M. Rockosi, Heather L. Morrison +6
The observed radial and vertical metallicity distribution of old stars in the Milky Way disk provides a powerful constraint on the chemical enrichment and dynamical history of the…
Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
Young Sun Lee, Timothy C. Beers, Deokkeun An +10
We employ measurements of the [alpha/Fe] ratio derived from low-resolution (R~2000) spectra of 17,277 G-type dwarfs from the SEGUE survey to separate them into likely thin- and thi…
Local Kinematics and the Local Standard of Rest
R. Schoenrich, J. Binney, W. Dehnen
We re-examine the stellar kinematics of the Solar neighbourhood in terms of the velocity of the Sun with respect to the local standard of rest. We show that the classical determina…
Origin and structure of the Galactic disc(s)
Ralph Schoenrich, James Binney
We examine the chemical and dynamical structure in the solar neighbourhood of a model Galaxy that is the endpoint of a simulation of the chemical evolution of the Milky Way in the…
Dust properties in M31.I.Basic properties and a discussion on age-dependent dust heating
M. Montalto, S. Seitz, A. Riffeser +3
Context. Spitzer Space Telescope observations and dust emission models are used to discuss the distribution of dust and its characteristics in M31. Together with GALEX FUV, NUV, an…