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Trends in the enrichment of elements with stellar ages are a powerful avenue to identify unexplained origins of the elements. We investigate the stellar abundance trends of low to intermediate-mass stars using the GALAH DR3 high-resolution…

Astrophysics of Galaxies · Physics 2024-10-15 Evans K. Owusu , Sven Buder , Ashley J. Ruiter , Ivo R. Seitenzahl , Nicolás Rodríguez-Segovia

Galactic chemical evolution models which include sodium from type II supernovae alone underestimate the abundance of sodium in the interstellar medium by a factor of two to three over about 3 dex in metallicity and predict a flat behaviour…

Astrophysics · Physics 2007-05-23 Robert G. Izzard , Brad K. Gibson , Richard J. Stancliffe

Stellar evolution models predict that internal mixing should cause some sodium overabundance at the surface of red giants more massive than ~ 1.5--2.0 Msun. The surface aluminium abundance should not be affected. Nevertheless, observational…

We present sodium abundances for a sample of nearby stars. All results have been derived from NLTE statistical equilibrium calculations. The influence of collisional interactions with electrons and hydrogen atoms is evaluated by comparison…

Astrophysics · Physics 2009-11-10 J. R. Shi , T. Gehren , G. Zhao

Inhomogeneous chemical evolution models of galaxies which try to reproduce the scatter seen in element-to-iron ratios of metal-poor halo stars are heavily dependent on theoretical nucleosynthesis yields of core-collapse supernovae. Hence…

Astrophysics · Physics 2009-11-06 D. Argast , M. Samland , F. -K. Thielemann , O. E. Gerhard

Context. The [Mg/Fe] abundance ratios are a fundamental fossil signature to trace the chemical evolution of the disc. Despite of the huge observational and theoretical effort, discrepancies between models and data are still present and…

Astrophysics of Galaxies · Physics 2022-07-20 Marco Palla , Pablo Santos-Peral , Alejandra Recio-Blanco , Francesca Matteucci

We investigate the chemical evolution of odd-numbered elements such as sodium (Na) and aluminum (Al) during the early epochs of the Galactic halo with the use of a model that reproduces the observed box-shaped distribution of extremely…

Astrophysics · Physics 2009-11-07 Takuji Tsujimoto , Toshikazu Shigeyama , Yuzuru Yoshii

Recent observations have shown that [P/Fe] in the Galactic stars decreases with increasing [Fe/H] for [Fe/H] > -1 whereas it is almost subsolar for [Fe/H]< -2. These [P/Fe] trends with [Fe/H] have not been well reproduced by previous…

Astrophysics of Galaxies · Physics 2024-05-13 Kenji Bekki , Takuji Tsujimoto

New detailed stellar yields of several elemental species are derived for massive stars in a wide range of masses (from 6 to 120 Msol) and metallicities (Z= 0.0004, 0.004, 0.008, 0.02, 0.05). Our calculations are based on the Padova…

Astrophysics · Physics 2009-10-12 L. Portinari , C. Chiosi , A. Bressan

We calculate the mean evolution of the iron-peak abundance ratios [(Cr,Mn,Co,Zn)/Fe] in the Galaxy, using modern supernova and hypernova chemical yields and a Galactic Chemical Evolution code that assumes homogeneous chemical evolution. We…

Astrophysics of Galaxies · Physics 2020-07-01 J. J. Grimmett , Amanda I. Karakas , Alexander Heger , Bernhard Müller , Christopher West

We analyse for the first time the radial abundance gradients of the disc stars of a disc galaxy simulated with our three dimensional, fully cosmological chemodynamical galaxy evolution code GCD+. We study how [Fe/H], [N/O], [O/Fe], [Mg/Fe]…

Astrophysics of Galaxies · Physics 2015-05-27 Awat Rahimi , Daisuke Kawata , Carlos Allende Prieto , Chris B. Brook , Brad K. Gibson , Alina Kiessling

We investigate the contribution of sub-Chandrasekhar mass Type Ia supernovae to the chemical enrichment of the Gaia Sausage galaxy, the progenitor of a significant merger event in the early life of the Milky Way. Using a combination of data…

Astrophysics of Galaxies · Physics 2021-07-21 Jason L. Sanders , Vasily Belokurov , Kai T. F. Man

We determined the silicon abundances of 253 metal-poor stars in the metallicity range $-4<\mathrm{[Fe/H]} <-1.5$, based on non-local thermodynamic equilibrium (NLTE) line formation calculations of neutral silicon and high-resolution spectra…

Solar and Stellar Astrophysics · Physics 2015-05-19 L. Zhang , T. Karlsson , N. Christlieb , A. J. Korn , P. S. Barklem , G. Zhao

We calculate the evolution of heavy element abundances from C to Zn in the solar neighborhood adopting our new nucleosynthesis yields. Our yields are calculated for wide ranges of metallicity (Z=0-Z_\odot) and the explosion energy (normal…

Astrophysics · Physics 2008-11-26 C. Kobayashi , H. Umeda , K. Nomoto , N. Tominaga , T. Ohkubo

Using data from the GALAH survey, we explore the dependence of elemental abundances on stellar age and metallicity among Galactic disc stars. We find that the abundance of most elements can be predicted from age and [Fe/H] with an intrinsic…

Sodium abundances have been determined in a large number of giants of open clusters but conflicting results, ranging from solar values to overabundances of up to five orders of magnitude, have been found. The reasons for this disagreement…

Solar and Stellar Astrophysics · Physics 2015-06-04 Rodolfo Smiljanic

I present a review of chemical evolution models of the solar neighborhood. I give special attention to the necessary ingredients to reproduce the observed [Xi/Fe] ratios in nearby metal and super metal rich stars, and to the chemical…

Astrophysics · Physics 2007-05-23 L. Carigi

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

We develop a hybrid model of galactic chemical evolution that combines a multi-ring computation of chemical enrichment with a prescription for stellar migration and the vertical distribution of stellar populations informed by a cosmological…

We have studied 23 long-lived G dwarfs that belong to the thin disk and thick disk stellar populations. Abundances have been derived for 24 elements: O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd,…

Astrophysics · Physics 2008-11-26 Mary-Margaret Brewer , Bruce W. Carney
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