Chemical Evolution of Galaxies

G. A. Shields

Home/Archive/arXiv

arXiv · astro-ph/0104237

Chemical Evolution of Galaxies

G. A. Shields

View original source ↗Read source document ↗Export metadata ↓

Abstract

Chemical abundances provide important clues to the evolution of galaxies. Ionized nebulae are one of the main sources of chemical abundance measurements, especially in external galaxies. Studies of H II regions have shown that the overall metallicity of galaxies increases with galactic luminosity, and that spiral galaxies characteristically have radial gradients in chemical composition. There are indications of environmental influences on chemical abundances. Planetary nebulae provide another measure of abundances in the Milky Way and other galaxies. Space facilities have allowed measurements for elements that are inaccessible at optical wavelengths. Large telescopes make possible the study of individual stars in external galaxies and the study of interstellar abundances in galaxies at intermediate and high redshifts. These advances promise exciting times as astrophysicists strive to paint a complete picture of galactic evolution from the Big Bang to the present.

Explore related subjects

astro-ph

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

G. A. Shields. 2001-04-13. Chemical Evolution of Galaxies. https://arxiv.org/abs/astro-ph/0104237

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Cosmic Conundrums with Quantum Corrections

Darh energy was discovered over 25 years ago and we do not have an explanation of it. Dark matter comprises 95% of matter in the universe and we still don't know what it is. The Webb telescope has been finding fully formed galaxies with massive black holes millions of times the mass of the sun in the early universe and we don't have any explanation. A quantum density limitation will be used to solve these and other outstanding problems.

astro-ph↗

arXiv2026

On binary pulsars and the force of gravity

The energy-momentum budget of the astrophysical systems can be studied by the exact local conservation equation derived by Landau and Lifshitz. We show that a similar equation is valid for the Einstein-Cartan gravity. We reanalyze a binary pulsar system using the Landau-Lifshitz conservation equation and show that the orbital period change rate can be completely understood as a curvature backreaction process. Taking into account the detailed theoretical and observational research of relativistic binary pulsar systems, especially the system of Hulse and Taylor, we conclude that general relativity and astrophysical observations rule out the existence of gravitational radiation. We comment upon the LIGO GW events and their alternative explanation, as well as the recent pulsar timing arrays data.

astro-ph↗

arXiv2026

Oscillation frequencies and mode lifetimes in alpha Centauri A

We analyse our recently-published velocity measurements of alpha Cen A (Butler et al. 2004). After adjusting the weights on a night-by-night basis in order to optimize the window function to minimize sidelobes, we extract 42 oscillation frequencies with l=0 to 3 and measure the large and small frequency separations. We give fitted relations to these frequencies that can be compared with theoretical models and conclude that the observed scatter about these fits is due to the finite lifetimes of the oscillation modes. We estimate the mode lifetimes to be 1-2 d, substantially shorter than in the Sun.

astro-ph↗