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The details of bulge formation via collapse, mergers, secular processes or their interplay remain unresolved. To start answering this question and quantify the importance of distinct mechanisms, we mapped a sample of three galactic bulges…

Within the framework of the current models for the slow neutron capture (s) process in Asymptotic Giant Branch (AGB) stars we explore the uncertainties introduced by the assumptions made on stellar modeling. On the basis of star models…

天体物理学 · 物理学 2009-10-31 Maria Lugaro , Falk Herwig

This paper presents the first census of Galactic post-Asymptotic Giant Branch stars in the HR diagram. We combined Gaia DR3 parallax-based distances with extinction corrected integrated fluxes, and derived luminosities for a sample of 185…

太阳与恒星天体物理 · 物理学 2022-08-17 René D. Oudmaijer , Emma R. M. Jones , Miguel Vioque

Abridged: Getting a better understanding of the evolution and nucleosynthetic yields of the most metal-poor stars (appr. Z<=10^-5) is critical because they are part of the big picture of the history of the primitive Universe. Yet many of…

We have determined detailed elemental abundances and stellar ages for a sample of now 38 microlensed dwarf and subgiant stars in the Galactic bulge. Stars with sub-solar metallicities are all old and have enhanced alpha-element abundances…

We obtained high-resolution near-IR spectra of 45 AGB stars located in the Galactic bulge. The aim of the project is to determine key elemental abundances in these stars to help constrain the formation history of the bulge. A further aim is…

We present a new model atmosphere analysis of nine central stars of planetary nebulae. This study is based on a new generation of realistic stellar model atmospheres for hot stars; state-of-the-art, hydrodynamically consistent, spherically…

天体物理学 · 物理学 2009-11-10 A. W. A. Pauldrach , T. L. Hoffmann , R. H. Mendez

We summarize what large surveys of the contemporary universe have taught us about the physics and phenomenology of the processes that link the formation and evolution of galaxies and their central supermassive black holes. We present a…

星系天体物理 · 物理学 2015-06-19 Timothy Heckman , Philip Best

To better understand the mixing and mass loss experienced by low-mass stars as they ascend the asymptotic giant branch (AGB), I have gathered from the literature the abundances of CNO and s-process elements in post-AGB stars in Galactic…

太阳与恒星天体物理 · 物理学 2023-11-09 William V. Dixon

We compute the chemical evolution of the Galactic bulge to explain the existence of two main stellar populations recently observed. After comparing model results and observational data we suggest that the old more metal poor stellar…

星系天体物理 · 物理学 2015-06-11 V. Grieco , F. Matteucci , A. Pipino , G. Cescutti

The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. We present a detailed framework for constraining model luminosity functions of TP-AGB stars using resolved…

This paper is focused on the transition phase between central stars and white dwarfs, i.e. objects in the effective temperature range 100,000 - 200,000 K. We confine our review to hydrogen-deficient stars because the common H-rich objects…

太阳与恒星天体物理 · 物理学 2015-05-30 K. Werner

We consider interesting results on the kinematics of the bulge, beginning with Mould's (1983) measurement of the velocity dispersion of the late M giants in the bulge, and carrying the discussion on to the present day, to discuss the…

The concept of overshoot has already been considered for numerous cases in stellar evolution calculations. We explore the consequences of overshoot at the convection zone which forms during the He-flash (thermal pulse) in AGB stars. We find…

天体物理学 · 物理学 2007-05-23 F. Herwig , T. Bloecker

Context. When low and intermediate-mass stars leave the Asymptotic Giant Branch (AGB) phase, and before they reach the Planetary Nebulae stage, they enter a very brief and rather puzzling stellar evolutionary stage named post-AGB. Aims. To…

太阳与恒星天体物理 · 物理学 2024-08-28 Iker González-Santamaría , Minia Manteiga , Arturo Manchado , Eva Villaver , Ana Ulla , Carlos Dafonte

Disks of gas accreting onto supermassive black holes may host numerous stellar-mass objects, formed within the disk or captured from a nuclear star cluster. We present a simplified model of stellar evolution applicable to these dense…

星系天体物理 · 物理学 2024-09-06 Alexander J. Dittmann , Matteo Cantiello

We study the asymptotic giant branch (AGB) evolution of stars with masses between $1~M_{\odot} - 8.5~M_{\odot}$. We focus on stars with a solar chemical composition, which allows us to interpret evolved stars in the Galaxy. We present a…

太阳与恒星天体物理 · 物理学 2018-02-14 P. Ventura , A. Karakas , F. Dell'Agli , D. A. García-Hernández , L. Guzman-Ramirez

We report a new hot post-asymptotic giant branch (PAGB) star in the Galactic globular cluster (GC) E3, which is one of the first of the identified PAGB stars in a GC to show a binary signature. The star stands out as the brightest source in…

太阳与恒星天体物理 · 物理学 2024-05-08 R. Kumar , A. Moharana , S. Piridi , A. C. Pradhan , K. G. Hełminiak , N. Ikonnikova , A. Dodin , R. Szczerba , M. Giersz , D. K. Ojha , M. R. Samal

We present an evolutionary sequence of a low mass star from the Asymptotic Giant Branch (AGB) through its post-AGB stage, during which its surface chemical composition changes from hydrogen-rich to strongly hydrogen-deficient as consequence…

天体物理学 · 物理学 2007-05-23 F. Herwig , T. Bloecker , N. Langer , T. Driebe

The structural and nucleosynthetic evolution of 3, 4, 5, 6 and \mass{7} stars with two metallicities ($Z = 0.005$ and 0.02) has been computed in detail, from the early pre-main sequence phase up to the thermally pulsing (TP) AGB phase or…

天体物理学 · 物理学 2018-06-27 Manuel Forestini , Corinne Charbonnel