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We present a detailed study of the composition of 20 M giants in the Galactic center with 15 of them confirmed to be in the Nuclear Star Cluster. As a control sample we have also observed 7 M giants in the Milky Way Disk with similar…

k-mers (nucleotide strings of length k) form the basis of several algorithms in computational genomics. In particular, k-mer abundance information in sequence data is useful in read error correction, parameter estimation for genome…

Data Structures and Algorithms · Computer Science 2016-09-20 Naveen Sivadasan , Rajgopal Srinivasan , Kshama Goyal

We obtained an axi-symmetric model for the large-scale distribution of stars and dust in the Milky Way (MW) using a radiative transfer code that can account for the existing near-infrared (NIR)/mid-infrared/submm all-sky emission maps of…

Astrophysics of Galaxies · Physics 2022-01-19 Giovanni Natale , Cristina C. Popescu , Mark Rushton , Ruizhi Yang , Jordan J. Thirlwall , Dumitru Pricopi

Metal-poor M subdwarfs are among the oldest stellar populations and carry valuable information about the chemical enrichment history of the Milky Way. The measurements of chemical abundances of these stars therefore provide essential…

Solar and Stellar Astrophysics · Physics 2025-05-02 Neda Hejazi , Sebastien Lepine , Thomas Nordlander , Wei-Chun Jao , David R. Coria , Kathryn V. Lester

We analyse the chemical properties of a set of solar vicinity stars, and show that the small dispersion in abundances of \alpha-elements at all ages provides evidence that the SFH has been uniform throughout the thick disk. In the context…

Astrophysics of Galaxies · Physics 2015-04-13 M. Haywood , P. Di Matteo , O. Snaith , M. Lehnert

Kernel power $k$-means (KPKM) leverages a family of means to mitigate local minima issues in kernel $k$-means. However, KPKM faces two key limitations: (1) the computational burden of the full kernel matrix restricts its use on extensive…

Machine Learning · Computer Science 2025-11-14 Yixi Chen , Weixuan Liang , Tianrui Liu , Jun-Jie Huang , Ao Li , Xueling Zhu , Xinwang Liu

It is argued that the abundances of r-process related elements in stars with -3<[Fe/H]<-1 can be explained by the contributions of three sources. The sources are: the first generations of very massive (>100 solar masses) stars that are…

Astrophysics · Physics 2009-11-06 Y. -Z. Qian , G. J. Wasserburg

Heavy elements are synthesized by the r-process in neutron star mergers and potentially in rare supernovae linked to strong magnetic fields. Expensive hydrodynamic simulations of these extreme environments are usually post-processed to…

High Energy Astrophysical Phenomena · Physics 2025-06-03 Jan Kuske , Almudena Arcones , Moritz Reichert

We search for signatures of past accretion events in the Milky Way in the recently published catalogue by Nordstrom et al.(2004), containing accurate spatial and kinematic information as well as metallicities for 13240 nearby stars. To…

Astrophysics · Physics 2009-11-11 Amina Helmi , J. F. Navarro , B. Nordstrom , J. Holmberg , M. G. Abadi , M. Steinmetz

[Abridged] Ensemble studies of red-giant stars with exquisite asteroseismic, spectroscopic, and astrometric constraints offer a novel opportunity to recast and address long-standing questions concerning the evolution of stars and of the…

In this paper, we study the formation and chemical evolution of the Milky Way disc with particular focus on the abundance patterns ([$\alpha$/Fe] vs. [Fe/H]) at different Galactocentric distances, the present-time abundance gradients along…

Astrophysics of Galaxies · Physics 2018-09-12 V. Grisoni , E. Spitoni , F. Matteucci

Stellar parameters and abundances provide crucial insights into stellar and Galactic evolution studies. In this work, we developed a convolutional neural network (CNN) to estimate stellar parameters: effective temperature…

Astrophysics of Galaxies · Physics 2025-06-23 Haoyang Liu , Cuihua Du , Mingji Deng , Jian Zhang

The abundances of iron and oxygen are homogeneously determined in a sample of 523 nearby (d<150 pc) FGK disk and halo stars with metallicities in the range -1.5<[Fe/H]<0.5. The oxygen abundances were inferred from a restricted non-LTE…

Astrophysics · Physics 2009-11-13 I. Ramirez , C. Allende Prieto , D. L. Lambert

With the advent of large spectroscopic surveys the amount of high quality chemo-dynamical data in the Milky Way (MW) increased tremendously. Accurately and correctly capturing and explaining the detailed features in the high-quality…

The chemical evolution of the Milky Way is investigated using a dual-phase metal-enriched infall model in which primordial gas fuels the earliest epoch of star formation, followed by the ongoing formation of stars from newly accreted gas.…

Astrophysics · Physics 2009-11-07 Yeshe Fenner , Brad K. Gibson

The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that…

Astrophysics of Galaxies · Physics 2025-07-16 A. Feldmeier-Krause , T. Veršič , G. van de Ven , E. Gallego-Cano , N. Neumayer

The atmospheric parameters and abundances of Mg, Si, Ca, and Ti have been determined for 20 stars using the Gaia DR2 parallaxes, high-resolution spectra, and the non-local thermodynamic equilibrium (non-LTE) line formation modeling. A…

Solar and Stellar Astrophysics · Physics 2019-09-04 Lyudmila Mashonkina , Maria Neretina , Tatyana Sitnova , Yuri Pakhomov

The Ks band differential star count of the Two Micron All Sky Survey (2MASS) is used to derive the global structure parameters of the smooth components of the Milky Way. To avoid complication introduced by other fine structures and…

Astrophysics of Galaxies · Physics 2015-05-28 Chan-Kao Chang , Chung-Ming Ko , Ting-Hung Peng

The Milky Way's stellar disk exhibits a bimodality in the [Fe/H] vs. [$\alpha$/Fe] plane, showing a distinct high-$\alpha$ and low-$\alpha$ sequence whose origin is still under debate. We examine the [Fe/H]-[$\alpha$/Fe] abundance plane in…

Astrophysics of Galaxies · Physics 2020-01-28 Tobias Buck

The ratios of elemental abundances observed in metal-poor stars of the Galactic halo provide a unique present-day record of the nucleosynthesis products of its earliest stars. While the heaviest elements were synthesized by the r- and…

Solar and Stellar Astrophysics · Physics 2015-06-15 Ruth C. Peterson
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