Results 221 to 230 of about 7,914 (245)

Lithium abundance at the formation of the Galaxy

Nature, 1982
The observed abundance of lithium in population I stars (young stars)1 seems to have been stable during the past 5 × 109 yr (ref. 2). This stability has been used previously1,3 to estimate the abundance of lithium at the time of formation of the Galaxy and at pre-galactic times1,3. But because the basis for this estimate was not completely satisfactory,
M. Spite, F. Spite
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He abundances in disc galaxies

Astronomy & Astrophysics, 2019
We investigate how the stellar and gas-phase He abundances evolve as a function of time within simulated star-forming disc galaxies with different star formation histories. We make use of a cosmological chemodynamical simulation for galaxy formation and evolution, which includes star formation as well as energy and chemical enrichment feedback from ...
Vincenzo, F., Miglio, A., Kobayashi, C., Mackereth, J. T., Montalban, J.   +4 more
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Chemical Abundances in Galaxies

1988
This article is intended as a brief overview of chemical abundances in galaxies other than our own. Attention is concentrated on global properties of ellipticals and spirals, and the methods by which abundances are estimated. References are predominantly to work which has appeared since the review of Pagel and Edmunds (1981).
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Abundances in dwarf irregular galaxies

Publications of the Astronomical Society of the Pacific, 1986
The results of abundance studies of dwarf irregular galaxies and similar objects are reviewed with special attention to variations in the CNO element group. Observations of the forbidden N II and semiforbidden C III lines in the most metal-poor galaxy known, IZw 18, are presented for the first time and CNO abundances are derived via a photoionization ...
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Chandra X-ray measurement of gas-phase heavy element abundances in the central parsec of the galaxy

Monthly Notices of the Royal Astronomical Society, 2023
, Mengfei Zhang, Mark Morris
exaly  

Abundance Gradients in Spiral Galaxies

1997
The study of HII regions in the disks of spiral galaxies has given us important information about their physical conditions. In particular the study of their chemical abundances soon showed the existence of negative gradients with higher abundance towards the centre of a galaxy (e.g. Pagel and Edmunds 1981; McCall 1982; Diaz 1989; Dinerstein 1990).
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Reviving old controversies: is the early Galaxy flat or round?

Astronomy and Astrophysics, 2020
M Haywood, P Bonifacio, E Caffau
exaly  

Extending Ultra-Diffuse Galaxy abundances to Milky Way analogues

Monthly Notices of the Royal Astronomical Society, 2022
Ananthan Karunakaran, Dennis Zaritsky
exaly  

Interstellar Abundances in External Galaxies

1977
This field has been excellently reviewed recently by Peimbert (1975), Burbidge and Burbidge (1975) and Searle (1975). The present discussion will cover work since these and in particular the evidence for composition gradients across galaxies and the systematics with galactic type.
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Chromium: NLTE abundances in metal-poor stars and nucleosynthesis in the Galaxy

Astronomy and Astrophysics, 2010
M Bergemann, G Cescutti
exaly