Article
Astronomy & Astrophysics
Federico Sestito, Daria Zaremba, Kim A. Venn, Lina D'Aoust, Christian Hayes, Jaclyn Jensen, Julio F. Navarro, Pascale Jablonka, Emma Fernandez-Alvar, Jennifer Glover, Alan W. Mcconnachie, Andre-Nicolas Chene
Summary: Stellar candidates in the extreme outskirts of the Ursa Minor dwarf galaxy have been discovered and confirmed to be part of the galaxy through observations and chemical analysis. The chemical patterns in UMi suggest an outside-in star-formation history and a low star-formation efficiency. Additionally, the analysis of the surface number density profile indicates that UMi's outskirts have been influenced by tidal effects.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
L. Mashonkina, Yu Pakhomov, T. Sitnova, P. Jablonka, S. A. Yakovleva, A. K. Belyaev
Summary: This study presents accurate atmospheric parameters and NLTE abundances for very metal-poor stars in the Sextans dwarf spheroidal galaxy. The stars exhibit alpha-enhancements and a tight relationship between Ba and Mg, suggesting a common origin in massive stars. Additionally, the study reveals a decline in alpha/Fe for stars with higher [Fe/H] values and a distinctive Ba enrichment pattern in one C-enhanced star.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Kanishk Pandey, Christopher West
Summary: Stellar evolution models require initial isotopic abundances as input, which are well known only for the Sun. To estimate input compositions for components with distinct chemical histories from the Galaxy, we present a partial isotopic history model for the Sculptor dwarf spheroidal galaxy. This model is fitted to observational data and follows the methodology of a previously constructed isotopic history model for the Galaxy. It provides estimates of isotopic abundances for future nucleosynthesis studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
T. T. Hansen, J. D. Simon, T. S. Li, A. Frebel, I. Thompson, S. Shectman
Summary: Carbon-enhanced metal-poor (CEMP) stars are important tracers of early Galactic chemical evolution. This study focuses on six CEMP stars in the Carina dSph and compares their abundances to CEMP stars in other dSph galaxies and the Milky Way halo. Detailed elemental abundances were derived through spectroscopic analysis.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. Mashonkina, A. Arentsen, D. S. Aguado, A. Smogorzhevskii, M. Hampel, A. Karakas, F. Sestito, N. F. Martin, K. A. Venn, J. I. Gonzalez Hernandez
Summary: This study presents high-resolution spectroscopic follow-up of the carbon-enhanced metal-poor star Pristine 184237. The atmospheric parameters and abundances for 32 elements were determined, revealing unique element abundance patterns. It is the first star of the CEMP-r/s subclass identified in the inner Galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jordan Schofield, Marco Pignatari, Richard J. Stancliffe, Peter Hoppe
Summary: In this study, isotopic abundances of C, N, Al, Si, and Ti measured in presolar grains were compared with predictions from 21 CCSN models. The research found that high energy models favor the formation of a C/Si zone enriched in C-12, Si-28, and Ti-44.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jinning Liang, Eda Gjergo, XiLong Fan
Summary: This paper investigates the consistency between Galactic chemical evolution models and observed abundance patterns. Different yield models are tested and found to produce different results, and the scatter of observed abundances cannot be explained by simple averaging of results.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Camilla C. Borre, Victor Aguirre Borsen-Koch, Amina Helmi, Helmer H. Koppelman, Martin B. Nielsen, Jakob L. Rorsted, Dennis Stello, Amalie Stokholm, Mark L. Winther, Guy R. Davies, Marc Hon, J. M. Diederik Kruijssen, Chervin F. P. Laporte, Claudia Reyes, Jie Yu
Summary: By studying the ages of remnant stars, we can estimate the merger times of the Milky Way and gain a better understanding of its evolutionary history. Using data from multiple sources, we have successfully determined the ages of 21 red giant stars and classified eight of them as part of one of the largest merger events in the history of our Galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
G. Contursi, P. de Laverny, A. Recio-Blanco, E. Spitoni, P. A. Palicio, E. Poggio, V. Grisoni, G. Cescutti, F. Matteucci, L. Spina, M. A. Alvarez, G. Kordopatis, C. Ordenovic, I. Oreshina-Slezak, H. Zhao
Summary: The Gaia third data release provides chemically mapped millions of individual chemical abundances in the Milky Way, including cerium. By analyzing the Gaia/RVS data, it is found that the cerium content in the Milky Way is quite flat and there is a flat radial gradient in the disc component.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Ann Merchant Boesgaard, Constantine P. Deliyannis, Michael G. Lum, Ashley Chontos
Summary: The surface content of lithium and beryllium in solar-type stars reveals important information about their temperature structure and physical processes. Lithium shows a strong trend with temperature, while beryllium shows little variation. The abundances of lithium decrease with increasing metallicity, while beryllium increases due to Galactic enrichment. Lithium declines with age, while beryllium may slightly increase.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Pratik J. Gandhi, Andrew Wetzel, Philip F. Hopkins, Benjamin J. Shappee, Coral Wheeler, Claude-Andre Faucher-Giguere
Summary: Type la supernovae play a crucial role in feedback and elemental enrichment in galaxies. Recent surveys have found that the rate of supernova la in lower mass galaxies may be higher than in the Milky Way. The study suggests that models in which the supernova la rate increases with decreasing metallicity provide better agreement with observations. These findings are important for understanding galaxy formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Baitian Tang, Jiajun Zhang, Zhiqiang Yan, Zhiyu Zhang, Leticia Carigi, Jose G. Fernandez-Trincado
Summary: By studying the high-resolution O, Si, and Al abundances in 43 giant stars of the Sculptor dwarf galaxy using near-infrared APOGEE spectra, we confirm the trend of lower [alpha/Fe] in less massive galaxies. The low [Al/Fe] in Sculptor demonstrates its value in identifying stars born in dwarf galaxies rather than the Milky Way field stars.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
G. Cescutti, C. Morossi, M. Franchini, P. Di Marcantonio, C. Chiappini, M. Steffen, M. Valentini, P. Francois, N. Christlieb, C. Cortes, C. Kobayashi, E. Depagne
Summary: Researchers analyzed the barium lines in two halo stars, HD 6268 and HD 4306, finding that the former showed an s-process composition while the latter displayed an r-process isotopic pattern. This confirms the theoretical expectation that both r-process events and s-process contribution by rotating massive stars have affected the ancient halo of our Galaxy.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yutaka Hirai, Timothy C. Beers, Masashi Chiba, Wako Aoki, Derek Shank, Takayuki R. Saitoh, Takashi Okamoto, Junichiro Makino
Summary: Research suggests that most highly r-process-enhanced (RPE) stars are formed in low-mass dwarf galaxies, while stars with higher metallicity may be formed in situ. These findings contribute to our understanding of the assembly history of the Milky Way and the nucleosynthesis of heavy elements.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Marta Molero, Laura Magrini, Francesca Matteucci, Donatella Romano, Marco Palla, Gabriele Cescutti, Carlos Viscasillas Vazquez, Emanuele Spitoni
Summary: We investigate the origin of neutron-capture elements in the Galactic thin disc by analysing their abundance patterns and radial gradients. Our detailed two-infall chemical evolution model includes nucleosynthesis prescriptions for neutron-capture elements and considers different synthesis sources. We compare our model predictions with data from the Gaia-ESO survey and find good agreement regarding the [Eu/Fe] versus [Fe/H] diagram and the [Fe/H] gradient slope. However, the predicted [Eu/H] radial gradient slope is steeper than observed, prompting discussion on Galaxy-formation scenarios and stellar radial migration effects. We also note slight underpredictions for Mo and Nd and successful reproduction of the [Pr/Fe] versus [Fe/H] trend.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Salvadori, P. Bonifacio, E. Caffau, S. Korotin, S. Andreevsky, M. Spite, A. Skuladottir
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2019)
Article
Astronomy & Astrophysics
E. Caffau, L. Monaco, P. Bonifacio, S. Korotin, S. Andrievsky, S. Cristallo, M. Spite, F. Spite, L. Sbordone, P. Francois, G. Cescutti, S. Salvadori
ASTRONOMY & ASTROPHYSICS
(2019)
Article
Astronomy & Astrophysics
S. A. Korotin, S. M. Andrievsky, E. Caffau, P. Bonifaciou, E. Oliva
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
Sergei M. Andrievsky, George Wallerstein, Sergey A. Korotin, Valery V. Kovtyukh, Sergii V. Khrapaty, Yuri Rydyak, Tamara V. Mishenina, Wenjin Huang
ASTRONOMISCHE NACHRICHTEN
(2020)
Article
Astronomy & Astrophysics
C. Abia, H. M. Tabernero, S. A. Korotin, D. Montes, E. Marfil, J. A. Caballero, O. Straniero, N. Prantzos, I Ribas, A. Reiners, A. Quirrenbach, P. J. Amado, V. J. S. Bejar, M. Cortes-Contreras, S. Dreizler, Th Henning, S. Jeffers, A. Kaminski, M. Kurster, M. Lafarga, A. Lopez-Gallifa, J. C. Morales, E. Nagel, V. M. Passegger, S. Pedraz, C. Rodriguez Lopez, A. Schweitzer, M. Zechmeister
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
Leonid S. Lyubimkov, Sergey A. Korotin, Dmitry Petrov, Dmitry B. Poklad, David E. Mkrtichian, Inwoo Han, Byeong-Cheol Lee
Summary: For nine bright K giants within 100 pc of the sun, the fundamental parameters and LTE abundances of three light elements (Li, C, and O) were accurately determined. These stars have typical parameters for K giants, with varying ages and masses. Metallicity indices show variability among the stars.
ASTRONOMISCHE NACHRICHTEN
(2021)
Article
Astronomy & Astrophysics
C. Abia, P. de Laverny, S. Korotin, A. Asensio Ramos, A. Recio-Blanco, N. Prantzos
Summary: By analyzing the Rb and Zr abundances in KM-type giant stars, it was found that there is a Rb deficiency in giant stars, but once NLTE corrections are performed, the ratios are very close to solar values. This contrasts with the Rb deficiency found in M dwarfs, indicating potential differences in nucleosynthesis mechanisms for different types of stars.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
E. Caffau, P. Bonifacio, S. A. Korotin, P. Francois, R. Lallement, A. M. Matas Pinto, P. Di Matteo, M. Steffen, A. Mucciarelli, D. Katz, M. Haywood, L. Chemin, P. Sartoretti, L. Sbordone, S. M. Andrievsky, V. V. Kovtyukh, M. Spite, F. Spite, P. Panuzzo, F. Royer, F. Thevenin, H-G Ludwig, O. Marchal, G. Plum
Summary: The Gaia satellite's RVS lacks a wavelength calibration lamp, relying on known radial velocity stars for dispersion. Good ground-based observations in the RVS wavelength range are crucial for determining the LSF. Increasing the number of radial velocity standard stars and high-quality spectra for LSF calibration can enhance accuracy.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Sergei M. Andrievsky, Sergey A. Korotin, Valery V. Kovtyukh, Sergey Khrapaty, Yuri Rudyak
Summary: This study conducted a direct non-local thermodynamic equilibrium analysis of carbon and nitrogen lines in the spectra of nine RR Lyrae stars, showing an increase in nitrogen content in metallicity-deficient stars as a sign of the first dredge up. The effect is significantly enhanced by thermohaline mixing, particularly in metal-poor RR Lyrae stars, leading to a gradual decrease in C/N ratio as metallicity decreases. Oxygen abundance displays a similar dependence on metallicity as seen in Population II stars.
ASTRONOMISCHE NACHRICHTEN
(2021)
Article
Astronomy & Astrophysics
V Dobrovolskas, E. Kolomiecas, A. Kucinskas, J. Klevas, S. Korotin
Summary: The study did not find significant Ba-Na correlation or 2P-1P Ba abundance difference in 261 RGB stars in the Galactic globular cluster 47 Tuc, consistent with previous research findings. The average barium-to-iron ratio obtained suggests the abundance of primordial protocluster gas has not been altered during the cluster's subsequent chemical evolution.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
S. Korotin, A. Kucinskas
Summary: Previous studies have suggested that non-local thermodynamic equilibrium (NLTE) has a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. However, the use of more up-to-date atomic physics and new atomic data to construct a model atom indicates that deviations from LTE have a significant influence on the strength of the Be II 313 nm line. Particularly in metal-poor stars, NLTE effects become significant.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
E. Kolomiecas, V Dobrovolskas, A. Kucinskas, P. Bonifacio, S. Korotin
Summary: In this study, abundances of Na and Zr in the atmospheres of RGB stars in Galactic globular cluster 47 Tuc were determined, showing a slight Zr over-abundance in 2P stars and a correlation between Zr and Na.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. S. Lyubimkov, S. A. Korotin, D. Petrov, D. B. Poklad, D. O. Kudryavtsev, D. N. Baklanova
Summary: This study focuses on the red giants EK Eri and OU And, which are presumed to be descendants of magnetic Ap-stars, and analyzes their fundamental parameters and chemical composition. The study finds the abundances of 17 elements and the nitrogen abundance and carbon isotope ratio using molecular lines. It is determined that these giants have passed through deep convective mixing in the FDU phase based on the carbon isotope ratio. The research also concludes that none of the three giants have anomalies in the abundances of heavy elements and explores unexpected phenomena such as the presence of a magnetic field and lithium in the atmospheres.
Article
Astronomy & Astrophysics
V. V. Kovtyukh, S. A. Korotin, S. M. Andrievsky, N. Matsunaga, K. Fukue
Summary: This paper presents a revised abundance analysis of four yellow supergiant stars Cepheids located in the Galactic nucleus. The results confirm solar metallicity level at the Galaxy center and suggest that the program stars may originate from an interstellar medium with homogeneous chemical properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
S. A. Korotin
ASTRONOMY LETTERS-A JOURNAL OF ASTRONOMY AND SPACE ASTROPHYSICS
(2020)
