Search Results - "Bergemann, Maria"

Ionization balance of Ti in the photospheres of the Sun and four late-type stars by Bergemann, Maria

“…In this paper we investigate statistical equilibrium of Ti in the atmospheres of late-type stars. The Ti i/Ti ii level populations are computed with available…”
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Discovery and characterization of 3000+ main-sequence binaries from APOGEE spectra by El-Badry, Kareem, Ting, Yuan-Sen, Rix, Hans-Walter, Quataert, Eliot, Weisz, Daniel R, Cargile, Phillip, Conroy, Charlie, Hogg, David W, Bergemann, Maria, Liu, Chao

“…Abstract We develop a data-driven spectral model for identifying and characterizing spatially unresolved multiple-star systems and apply it to APOGEE DR13…”
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Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies by Kirby, Evan N., Xie, Justin L., Guo, Rachel, de los Reyes, Mithi A. C., Bergemann, Maria, Kovalev, Mikhail, Shen, Ken J., Piro, Anthony L., McWilliam, Andrew

“…Abstract There is no consensus on the progenitors of Type Ia supernovae (SNe Ia) despite their importance for cosmology and chemical evolution. We address this…”
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Metal Mixing in the r-process Enhanced Ultrafaint Dwarf Galaxy Reticulum II by Ji, Alexander P., Simon, Joshua D., Roederer, Ian U., Magg, Ekaterina, Frebel, Anna, Johnson, Christian I., Klessen, Ralf S., Magg, Mattis, Cescutti, Gabriele, Mateo, Mario, Bergemann, Maria, Bailey, John I.

“…Abstract The ultrafaint dwarf galaxy Reticulum II was enriched by a single rare and prolific r -process event. The r -process content of Reticulum II thus…”
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Unveiling systematic biases in the 1D LTE excitation-ionization balance of Fe for FGK stars: a novel approach to determination of stellar parameters by Ruchti, Gregory R., Bergemann, Maria, Serenelli, Aldo, Casagrande, Luca, Lind, Karin

“…We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars and provide a recommended methodology which…”
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RED SUPERGIANTS AS COSMIC ABUNDANCE PROBES: THE SCULPTOR GALAXY NGC 300 by Gazak, J Zachary, Kudritzki, Rolf, Evans, Chris, Patrick, Lee, Davies, Ben, Bergemann, Maria, Plez, Bertrand, Bresolin, Fabio, Bender, Ralf, Wegner, Michael, Bonanos, Alceste Z, Williams, Stephen J

“…We present a quantitative spectroscopic study of 27 red supergiants (RSGs) in the Sculptor Galaxy NGC 300. J-band spectra were obtained using KMOS on the Very…”
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Cobalt-Hydrogen Atomic and Ionic Collisional Data by Yakovleva, Svetlana A., Belyaev, Andrey K., Bergemann, Maria

“…Rate coefficients for inelastic processes in low-energy Co + H, Co + + H − , Co + + H , and Co 2 + + H − collisions are estimated using the quantum simplified…”
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Observational constraints on the origin of the elements – VII. NLTE analysis of Y ii lines in spectra of cool stars and implications for Y as a Galactic chemical clock by Storm, Nicholas, Bergemann, Maria

“…ABSTRACT Yttrium (Y), a key s-process element, is commonly used in nucleosynthesis studies and as a Galactic chemical clock when combined with magnesium (Mg)…”
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Disk Heating, Galactoseismology, and the Formation of Stellar Halos by Johnston, Kathryn, Price-Whelan, Adrian, Bergemann, Maria, Laporte, Chervin, Li, Ting, Sheffield, Allyson, Majewski, Steven, Beaton, Rachael, Sesar, Branimir, Sharma, Sanjib

“…Deep photometric surveys of the Milky Way have revealed diffuse structures encircling our Galaxy far beyond the “classical” limits of the stellar disk. This…”
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Non-local Thermodynamic Equilibrium Stellar Spectroscopy with 1D and 〈3〉 Models. I. Methods and Application to Magnesium Abundances in Standard Stars by Bergemann, Maria, Collet, Remo, Amarsi, Anish M., Kovalev, Mikhail, Ruchti, Greg, Magic, Zazralt

“…We determine Mg abundances in six Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally and…”
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Non-LTE line formation of Fe in late-type stars - I. Standard stars with 1D and 〈3D〉 model atmospheres by Bergemann, Maria, Lind, K., Collet, R., Magic, Z., Asplund, M.

“…Abstract We investigate departures from local thermodynamic equilibrium (LTE) in the line formation of Fe for a number of well-studied late-type stars in…”
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Non-local Thermodynamic Equilibrium Stellar Spectroscopy with 1D and 〈3D〉 Models. I. Methods and Application to Magnesium Abundances in Standard Stars by Bergemann, Maria, Amarsi, Anish M., Kovalev, Mikhail, Collet, Remo, Ruchti, Greg, Magic, Zazralt

“…We determine Mg abundances in six Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally and…”
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Fundamental stellar parameters and metallicities from Bayesian spectroscopy: application to low- and high-resolution spectra by Schönrich, Ralph, Bergemann, Maria

“…We present a unified framework to derive fundamental stellar parameters by combining all available observational and theoretical information for a star. The…”
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NLTE analysis of Co i /Co ii lines in spectra of cool stars with new laboratory hyperfine splitting constants by Bergemann, Maria, Pickering, Juliet C., Gehren, Thomas

“…The analysis of stellar abundances for odd-Z Fe-peak elements requires accurate non-local thermodynamic equilibrium (NLTE) modelling of spectral lines fully…”
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Solar oxygen abundance by Bergemann, Maria, Hoppe, Richard, Semenova, Ekaterina, Carlsson, Mats, Yakovleva, Svetlana A, Voronov, Yaroslav V, Bautista, Manuel, Nemer, Ahmad, Belyaev, Andrey K, Leenaarts, Jorrit, Mashonkina, Lyudmila, Reiners, Ansgar, Ellwarth, Monika

“…ABSTRACT Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New…”
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Ionization balance of Ti in the photospheres of the Sun and four late-type stars: Ionization balance of Ti in late-type stars by Bergemann, Maria

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RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES. III. NLTE EFFECTS IN J-BAND MAGNESIUM LINES by Bergemann, Maria, Kudritzki, Rolf-Peter, Gazak, Zach, Davies, Ben, Plez, Bertrand

“…ABSTRACT Non-local thermodynamic equilibrium (NLTE) calculations for Mg i in red supergiant stellar atmospheres are presented to investigate the importance of…”
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THE TEMPERATURES OF RED SUPERGIANTS by Davies, Ben, Kudritzki, Rolf-Peter, Plez, Bertrand, Trager, Scott, Lancon, Ariane, Gazak, Zach, Bergemann, Maria, Evans, Chris, Chavassa, Andrea

“…We present a re-appraisal of the temperatures of red supergiants (RSGs) using their optical and near-infrared spectral energy distributions (SEDs). We have…”
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On the likelihoods of finding very metal-poor (and old) stars in the Milky Way’s disc, bulge, and halo by Sotillo-Ramos, Diego, Bergemann, Maria, Friske, Jennifer K S, Pillepich, Annalisa

“…ABSTRACT Recent observational studies have uncovered a small number of very metal-poor (VMP) stars with cold kinematics in the Galactic disc and bulge…”
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Signatures of unresolved binaries in stellar spectra: implications for spectral fitting by El-Badry, Kareem, Rix, Hans-Walter, Ting, Yuan-Sen, Weisz, Daniel R., Bergemann, Maria, Cargile, Phillip, Conroy, Charlie, Eilers, Anna-Christina

“…Abstract The observable spectrum of an unresolved binary star system is a superposition of two single-star spectra. Even without a detectable velocity offset…”
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