Publications by Ralph Schoenrich


Warp, waves, and wrinkles in the Milky Way

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 478 (2018) 3809-3824

R Schonrich, W Dehnen


Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 475 (2018) 5487-5500

VS Aguirre, M Bojsen-Hansen, D Slumstrup, L Casagrande, D Kawata, I Ciuca, R Handberg, MN Lund, JR Mosumgaard, D Huber, JA Johnson, MH Pinsonneault, AM Serenelli, D Stello, J Tayar, JC Bird, S Cassisi, M Hon, M Martig, PE Nissen, HW Rix, R Schonrich, C Sahlholdt, WH Trick, J Yu


The origin of the Gaia phase-plane spiral

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 481 (2018) 1501-1506

J Binney, R Schonrich


Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk.

Nature 555 (2018) 334-337

M Bergemann, B Sesar, JG Cohen, AM Serenelli, A Sheffield, TS Li, L Casagrande, KV Johnston, CFP Laporte, AM Price-Whelan, R Schönrich, A Gould

Our Galaxy is thought to have an active evolutionary history, dominated over the past ten billion years or so by star formation, the accretion of cold gas and, in particular, the merging of clumps of baryonic and dark matter. The stellar halo-the faint, roughly spherical component of the Galaxy-reveals rich 'fossil' evidence of these interactions, in the form of stellar streams, substructures and chemically distinct stellar components. The effects of interactions with dwarf galaxies on the content and morphology of the Galactic disk are still being explored. Recent studies have identified kinematically distinct stellar substructures and moving groups of stars in our Galaxy, which may have extragalactic origins. There is also mounting evidence that stellar overdensities (regions with greater-than-average stellar density) at the interface between the outer disk and the halo could have been caused by the interaction of a dwarf galaxy with the disk. Here we report a spectroscopic analysis of 14 stars from two stellar overdensities, each lying about five kiloparsecs above or below the Galactic plane-locations suggestive of an association with the stellar halo. We find that the chemical compositions of these two groups of stars are almost identical, both within and between these overdensities, and closely match the abundance patterns of stars in the Galactic disk. We conclude that these stars came from the disk, and that the overdensities that they are part of were created by tidal interactions of the disk with passing or merging dwarf galaxies.


On the Kinematic Signature of the Galactic Warp As Revealed By the LAMOST-TGAS Data

ASTROPHYSICAL JOURNAL 864 (2018) ARTN 129

Y Huang, R Schonrich, X-W Liu, B-Q Chen, H-W Zhang, H-B Yuan, M-S Xiang, C Wang, Z-J Tian


Inflow, Outflow, Yields, and Stellar Population Mixing in Chemical Evolution Models

ASTROPHYSICAL JOURNAL 835 (2017) ARTN 224

BH Andrews, DH Weinberg, R Schonrich, JA Johnson


Understanding inverse metallicity gradients in galactic discs as a consequence of inside-out formation

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 467 (2017) 1154-1174

R Schonrich, PJ McMillan


Non-local Thermodynamic Equilibrium Stellar Spectroscopy with 1D and 3D Models. II. Chemical Properties of the Galactic Metal-poor Disk and the Halo

Astrophysical Journal 847 (2017)

M Bergemann, R Collet, R Schönrich, R Andrae, M Kovalev, G Ruchti, CJ Hansen, Z Magic

© 2017. The American Astronomical Society. All rights reserved. From exploratory studies and theoretical expectations it is known that simplifying approximations in spectroscopic analysis (local thermodynamic equilibrium (LTE), 1D) lead to systematic biases of stellar parameters and abundances. These biases depend strongly on surface gravity, temperature and, in particular, for LTE versus non-LTE (NLTE), on metallicity of the stars. Here we analyze the [Mg/Fe] and [Fe/H] plane of a sample of 326 stars, comparing LTE and NLTE results obtained using 1D hydrostatic models and averaged models. We show that compared to the NLTE benchmark, the other three methods display increasing biases toward lower metallicities, resulting in false trends of [Mg/Fe] against [Fe/H] , which have profound implications for interpretations by chemical evolution models. In our best NLTE model, the halo and disk stars show a clearer behavior in the [Mg/Fe]-[Fe/H] plane, from the knee in abundance space down to the lowest metallicities. Our sample has a large fraction of thick disk stars and this population extends down to at least [Fe/H] ∼ -1.6 dex, further than previously proven. The thick disk stars display a constant [Mg/Fe] ≈ 0.3 dex, with a small intrinsic dispersion in [Mg/Fe] that suggests that a fast SN Ia channel is not relevant for the disk formation. The halo stars reach higher [Mg/Fe] ratios and display a net trend of [Mg/Fe] at low metallicities, paired with a large dispersion in [Mg/Fe] . These indicate the diverse origin of halo stars from accreted low-mass systems to stochastic/inhomogeneous chemical evolution in the Galactic halo.


Assessing distances and consistency of kinematics in Gaia/TGAS

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 472 (2017) 3979-3998

R Schonrich, M Aumer


The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 233 (2017) ARTN 25

FD Albareti, C Allende Prieto, A Almeida, F Anders, S Anderson, BH Andrews, A Aragon-Salamanca, M Argudo-Fernandez, E Armengaud, E Aubourg, V Avila-Reese, C Badenes, S Bailey, B Barbuy, K Barger, J Barrera-Ballesteros, C Bartosz, S Basu, D Bates, G Battaglia, F Baumgarten, J Baur, J Bautista, TC Beers, F Belfiore, M Bershady, S Bertran de Lis, JC Bird, D Bizyaev, GA Blanc, M Blanton, M Blomqvist, AS Bolton, J Borissova, J Bovy, WN Brandt, J Brinkmann, JR Brownstein, K Bundy, E Burtin, NG Busca, HO Camacho Chavez, MC Diaz, M Cappellari, R Carrera, Y Chen, B Cherinka, E Cheung, C Chiappini, D Chojnowski, C-H Chuang, H Chung, RF Cirolini, N Clerc, RE Cohen, JM Comerford, J Comparat, JC do Nascimento, M-C Cousinou, K Covey, JD Crane, R Croft, K Cunha, J Darling, DJW Jr, K Dawson, L Da Costa, GDS Ilha, AD Machado, T Delubac, N De Lee, A De la Macorra, S De la Torre, AM Diamond-Stanic, J Donor, J Jose Downes, N Drory, C Du, HDMD Bourboux, T Dwelly, G Ebelke, A Eigenbrot, DJ Eisenstein, YP Elsworth, E Emsellem, M Eracleous, S Escoffier, ML Evans, J Falcon-Barroso, X Fan, G Favole, E Fernandez-Alvar, JG Fernandez-Trincado, D Feuillet, SW Fleming, A Font-Ribera, G Freischlad, P Frinchaboy, H Fu, Y Gao, RA Garcia, R Garcia-Dias, DA Garcia-Hernandez, AE Garcia Perez, P Gaulme, J Ge, D Geisler, B Gillespie, HG Marin, L Girardi, D Goddard, YG Maqueo Chew, V Gonzalez-Perez, K Grabowski, P Green, CJ Grier, T Grier, H Guo, J Guy, A Hagen, M Hall, P Harding, RE Harley, S Hasselquist, S Hawley, CR Hayes, F Hearty, S Hekker, H Hernandez Toledo, S Ho, DW Hogg, K Holley-Bockelmann, JA Holtzman, PH Holzer, J Hu, D Huber, TA Hutchinson, HS Hwang, HJ Ibarra-Medel, II Ivans, K Ivory, K Jaehnig, TW Jensen, JA Johnson, A Jones, E Jullo, T Kallinger, K Kinemuchi, D Kirkby, M Klaene, J-P Kneib, JA Kollmeier, I Lacerna, RR Lane, D Lang, P Laurent, DR Law, A Leauthaud, J-M Le Goff, C Li, C Li, N Li, R Li, F-H Liang, Y Liang, M Lima, L Lin, L Lin, Y-T Lin, C Liu, D Long, S Lucatello, N MacDonald, CL MacLeod, JT Mackereth, S Mahadevan, MA Geimba Maia, R Maiolino, SR Majewski, O Malanushenko, V Malanushenko, ND Mallmann, A Manchado, C Maraston, R Marques-Chaves, I Martinez Valpuesta, KL Masters, S Mathur, ID McGreer, A Merloni, MR Merrifield, S Meszaros, A Meza, A Miglio, I Minchev, K Molaverdikhani, AD Montero-Dorta, B Mosser, D Muna, A Myers, P Nair, K Nandra, M Ness, JA Newman, RC Nichol, DL Nidever, C Nitschelm, J O'Connell, A Oravetz, DJ Oravetz, Z Pace, N Padilla, N Palanque-Delabrouille, K Pan, J Parejko, I Paris, C Park, JA Peacock, S Peirani, M Pellejero-Ibanez, S Penny, WJ Percival, JW Percival, I Perez-Fournon, P Petitjean, M Pieri, MH Pinsonneault, A Pisani, F Prada, A Prakash, N Price-Jones, MJ Raddick, M Rahman, A Raichoor, SB Rembold, AM Reyna, J Rich, H Richstein, J Ridl, RA Riffel, R Riffel, H-W Rix, AC Robin, CM Rockosi, S Rodriguez-Torres, TS Rodrigues, N Roe, AR Lopes, C Roman-Zuniga, AJ Ross, G Rossi, J Ruan, R Ruggeri, JC Runnoe, S Salazar-Albornoz, M Salvato, SF Sanchez, AG Sanchez, JR Sanchez-Gallego, BX Santiago, R Schiavon, JS Schimoia, E Schlafly, DJ Schlegel, DP Schneider, R Schonrich, M Schultheis, A Schwope, H-J Seo, A Serenelli, B Sesar, Z Shao, M Shetrone, M Shull, VS Aguirre, MF Skrutskie, A Slosar, M Smith, VV Smith, J Sobeck, G Somers, D Souto, DV Stark, KG Stassun, M Steinmetz, D Stello, TS Bergmann, MA Strauss, A Streblyanska, GS Stringfellow, G Suarez, J Sun, M Taghizadeh-Popp, B Tang, C Tao, J Tayar, M Tembe, D Thomas, J Tinker, R Tojeiro, C Tremonti, N Troup, JR Trump, E Unda-Sanzana, O Valenzuela, R Van den Bosch, M Vargas-Magana, JA Vazquez, S Villanova, M Vivek, N Vogt, D Wake, R Walterbos, Y Wang, E Wang, BA Weaver, A-M Weijmans, DH Weinberg, KB Westfall, DG Whelan, E Wilcots, V Wild, RA Williams, J Wilson, WM Wood-Vasey, D Wylezalek, T Xiao, R Yan, M Yang, JE Ybarra, C Yeche, F-T Yuan, N Zakamska, O Zamora, G Zasowski, K Zhang, C Zhao, G-B Zhao, Z Zheng, Z Zheng, Z-M Zhou, G Zhu, JC Zinn, H Zou


Chemical tagging with APOGEE: discovery of a large population of N-rich stars in the inner Galaxy

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 465 (2017) 501-524

RP Schiavon, O Zamora, R Carrera, S Lucatello, AC Robin, M Ness, SL Martell, VV Smith, DA Garcia-Hernandez, A Manchado, R Schonrich, N Bastian, C Chiappini, M Shetrone, JT Mackereth, RA Williams, S Meszaros, C Allende Prieto, F Anders, D Bizyaev, TC Beers, SD Chojnowski, K Cunha, C Epstein, PM Frinchaboy, AE Garcia Perez, FR Hearty, JA Holtzman, JA Johnson, K Kinemuchi, SR Majewski, D Muna, DL Nidever, DC Nguyen, RW O'Connell, D Oravetz, K Pan, M Pinsonneault, DP Schneider, M Schultheis, A Simmons, MF Skrutskie, J Sobeck, JC Wilson, G Zasowski


Migration and kinematics in growing disc galaxies with thin and thick discs

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 470 (2017) 3685-3706

M Aumer, J Binney, R Schonrich


Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 455 (2016) 987-1007

L Casagrande, VS Aguirre, KJ Schlesinger, D Stello, D Huber, AM Serenelli, R Schoenrich, S Cassisi, A Pietrinferni, S Hodgkin, AP Milone, S Feltzing, M Asplund


The Gaia-ESO Survey: Hydrogen lines in red giants directly trace stellar mass

ASTRONOMY & ASTROPHYSICS 594 (2016) ARTN A120

M Bergemann, A Serenelli, R Schonrich, G Ruchti, A Korn, S Hekker, M Kovalev, L Mashonkina, G Gilmore, S Randich, M Asplund, H-W Rix, AR Casey, P Jofre, E Pancino, A Recio-Blanco, P de Laverny, R Smiljanic, G Tautvaisiene, A Bayo, J Lewis, S Koposov, A Hourihane, C Worley, L Morbidelli, E Franciosini, G Sacco, L Magrini, F Damiani, JM Bestenlehner


Age-velocity dispersion relations and heating histories in disc galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 462 (2016) 1697-1713

M Aumer, J Binney, R Schonrich


The quiescent phase of galactic disc growth

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 459 (2016) 3326-3348

M Aumer, J Binney, R Schonrich


GALACTIC DYNAMICS AND RADIAL MIGRATION

MILKY WAY UNRAVELLED BY GAIA: GREAT SCIENCE FROM THE GAIA DATA RELEASES 67-68 (2015) 339-345

R Schoenrich


RINGS AND RADIAL WAVES IN THE DISK OF THE MILKY WAY

ASTROPHYSICAL JOURNAL 801 (2015) ARTN 105

Y Xu, HJ Newberg, JL Carlin, C Liu, L Deng, J Li, R Schoenrich, B Yanny


Origin of the high v(los) feature in the Galactic bar

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 454 (2015) 3166-3184

M Aumer, R Schoenrich


KINEMATIC DETECTION OF THE GALACTIC NUCLEAR DISK

ASTROPHYSICAL JOURNAL LETTERS 812 (2015) ARTN L21

R Schoenrich, M Aumer, SE Sale

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