scholarly journals Abundance Clues to Early Galactic Chemical Evolution

1988 ◽  
Vol 132 ◽  
pp. 577-583 ◽  
Author(s):  
James W. Truran
Keyword(s):  
Chemical Evolution ◽  
Globular Cluster ◽  
Current Knowledge ◽  
Spectroscopic Studies ◽  
Early History ◽  
Galactic Chemical Evolution ◽  
Abundance Patterns ◽  
History Of ◽  
Halo Population ◽  
Theoretical Considerations

High S/N spectroscopic studies of the abundance patterns characterizing extremely metal-deficient halo field stars and globular cluster stars have served to provide significant clues to and increasingly stringent boundary conditions upon the chemical evolution of the halo population of our galaxy. Guided by our current knowledge of nucleosynthesis as a function of stellar mass occurring in stars and supernovae, we identify some interesting constraints that these combined observational and theoretical considerations impose upon theories of the early history of our galaxy.

scholarly journals Chemical Evolution of Galaxies: Abundance Trends and Implications

1991 ◽  
Vol 145 ◽  
pp. 13-19
Author(s):  
James W. Truran
Keyword(s):  
Massive Stars ◽  
Current Knowledge ◽  
Spectroscopic Studies ◽  
Early History ◽  
Elemental Abundance ◽  
Type Ii ◽  
Halo Stars ◽  
Abundance Patterns ◽  
Abundance Trends ◽  
History Of

Recent spectroscopic studies of the elemental abundance patterns associated with extremely metal deficient field halo stars and globular cluster stars are briefly reviewed. These metal deficient stellar populations have been found to be characterized by abundance patterns which differ quite distinctly from those of solar system abundances, but are consistent with the view that they reflect primarily the nucleosynthesis products of the evolution of massive stars and associated Type II supernovae. Guided by our current knowledge of nucleosynthesis as a function of stellar mass occurring in stars and supernovae, we identify some interesting constraints upon theories of the formation and early history of our Galaxy.

scholarly journals The Early History of Our Galaxy: Chemical Evolution

1974 ◽  
Vol 58 ◽  
pp. 141-156
Author(s):  
Manuel Peimbert
Keyword(s):  
Chemical Evolution ◽  
Stellar Evolution ◽  
Local Group ◽  
Early History ◽  
The Other ◽  
Heavy Elements ◽  
Galactic Chemical Evolution ◽  
Chemical Abundance ◽  
Iron Abundance ◽  
History Of

A general review is given of chemical abundance determinations; particular emphasis is given to abundances of galactic and extragalactic metal-poor objects since presumably they represent the abundances of the primeval material from which our Galaxy was formed. The following results are stressed: (a) most of the helium present in the galaxies of the local group as well as in other galaxies was produced before these objects were formed, (b) the heavy elements were produced mainly as the result of stellar evolution, (c) there is a chemical abundance gradient in our Galaxy and, by analogy with other galaxies, it is expected to be steeper near the nucleus, (d) the carbon and oxygen content of our Galaxy increased at a rate different from the metals, reaching their present abundance earlier than the other heavy elements, and (e) the increase of the iron abundance in the disk of our Galaxy with time has been small while that of carbon is negligible; furthermore, as a group the super-metal-rich stars correspond to the old disk population. Several models of galactic chemical evolution are reviewed.

scholarly journals Extragalactic planetary nebulae: Tracers of the chemical evolution of nearby galaxies

2011 ◽  
Vol 7 (S283) ◽  
pp. 251-258 ◽  
Author(s):  
Laura Magrini ◽  
Letizia Stanghellini ◽  
Denise R. Gonçalves
Keyword(s):  
Chemical Evolution ◽  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Spectroscopic Studies ◽  
Disk Galaxies ◽  
Chemical Enrichment ◽  
History Of ◽  
External Galaxies ◽  
Low Metallicity ◽  
Nearby Galaxies

AbstractThe study of the chemical composition of Planetary Nebulae in external galaxies is of paramount importance for the fields of stellar evolution and chemical enrichment history of galaxies. In recent years a number of spectroscopic studies with 6-8m-class telescopes have been devoted to this subject improving our knowledge of, among other, the time-evolution of the radial metallicity gradient in disk galaxies, the chemical evolution of dwarf galaxies, and stellar evolution at low metallicity.

scholarly journals Spectroscopic Study of Cepheids in the Globular Cluster Omega Cen

1993 ◽  
Vol 139 ◽  
pp. 378-379
Author(s):  
Guillermo Gonzalez ◽  
George Wallerstein
Keyword(s):  
Spectroscopic Study ◽  
Globular Cluster ◽  
Preliminary Report ◽  
Globular Clusters ◽  
Spectroscopic Studies ◽  
Horizontal Branch ◽  
Present Sample ◽  
Abundance Patterns

AbstractUntil now there have been few spectroscopic studies of cepheids in globular clusters. In this preliminary report we present sample spectra of the stars Vl and V29 in ω Cen. Eventually, we hope to use the abundance patterns, masses, and period changes of cepheids to better understand post-horizontal branch evolution in globular clusters.

Chemical hormesis: its historical foundations as a biological hypothesis

2000 ◽  
Vol 19 (1) ◽  
pp. 2-31 ◽  
Author(s):  
E J Calabrese ◽  
L A Baldwin
Keyword(s):  
Risk Assessment ◽  
Experimental Research ◽  
Hazard Assessment ◽  
Current Knowledge ◽  
Early History ◽  
Assessment Practices ◽  
Related Research ◽  
Systematic Effort ◽  
History Of ◽  
Scientific Fields

Despite the long history of hormesis-related experimental research no systematic effort to describe its early history has been undertaken. The present paper attempts to reconstruct and assess the early history of such research and to evaluate how advances in related scientific fields affected the course of hormesis-related research. The purpose of this paper is not only to satisfy this gap in current knowledge, but also to provide a foundation for the assessment of how the concept of hormetic dose-response relationships may have affected the nature of the bioassay especially with respect to hazard assessment practices within a modern risk assessment Eramework.

Preface

2009 ◽  
Vol 81 (9) ◽  
pp. vi
Author(s):  
Devens Gust
Keyword(s):  
Spin Dynamics ◽  
Global Climate ◽  
Spectroscopic Studies ◽  
Fluorescent Markers ◽  
Molecular Logic ◽  
Northwestern University ◽  
Photosynthetic Antennas ◽  
History Of ◽  
Oral Presentations ◽  
Theoretical Considerations

<div>Extending a long history of successful conferences, the XXIInd IUPAC Symposium on Photochemistry was held in Göteborg, Sweden, from 28 July to 1 August 2008. It was attended by participants from 51 countries. The Symposium featured 7 plenary lectures, 12 invited lectures, 96 selected oral presentations, and 414 posters given by attendees. One of the highlights was the presentation of the Porter Medal to Prof. Michael R. Wasielewski of Northwestern University, USA. The title of his lecture was "Photodriven charge and spin dynamics in molecules and materials: From photosynthesis to spintronics."<br /><br />A featured theme of the Symposium was solar energy conversion in the context of global climate change and the energy crisis. However, a large variety of subjects were covered, including spectroscopy of single molecules and of nanostructures, molecular photochemistry in solution and in microhetero - geneous media, photochemistry of pharmaceuticals, fluorescent markers and sensors, photochemically based molecular logic, supramolecular units mimicking photosynthetic antennas and reaction centers, photopolymerizations and photochemistry in solid state, theoretical considerations and calculations of excited states, and spectroscopic studies of biological photosensors and biomedically important materials. Many of the topics were of both fundamental scientific interest and practical and technological importance. The next Symposium will be held in Ferrara, Italy in 2010.<br /><br />This issue of <i>Pure and Applied Chemistry</i> contains a collection of papers based on plenary and invited lectures given at the Symposium and kindly supplied by the speakers. They cover a variety of modern photochemical topics and appear in the order of their presentation at the Symposium. They help illustrate the vital place of modern photochemistry in promoting the health and welfare of humanity, and indeed of all life on the planet.</a> <br /><br /><i>Devens Gust</i><br />Conference Editor<br /></div>

Re-examining the early history of the Leiden jar: Stabilization and variation in transforming a phenomenon into a fact

2018 ◽  
Vol 56 (3) ◽  
pp. 314-342 ◽  
Author(s):  
Cibelle Celestino Silva ◽  
Peter Heering
Keyword(s):  
Knowledge Production ◽  
Current Knowledge ◽  
Early Period ◽  
Electrical Circuit ◽  
Early History ◽  
Primary Sources ◽  
New Device ◽  
Scientific Knowledge Production ◽  
History Of

In this paper, we examine the period that immediately followed the invention of the Leiden jar. Historians of science have developed narrations that emphasize the role of grounding during the process of charging the jar. In this respect, this episode shows significant aspects that can be used to characterize science, scientific knowledge production, and the nature of science. From our own experimentation, we learned that grounding was not necessary in order to produce the effect. These experiences inspired us to go back to primary sources. In doing so, we came to a new understanding of the early period after Kleist’s and Musschenbroek’s initial creation of the effect. From our analysis, we conclude that it is not the grounding which was perceived as a major innovation (as well as a challenge) during this early period of the discussion but the concept of an electrical circuit. This understanding was fundamental in characterizing the Leiden jar as a new device challenging the then current knowledge of experimental practices in the field of electricity.

scholarly journals Supernova Nucleosynthesis in the early universe

2008 ◽  
Vol 4 (S255) ◽  
pp. 189-193
Author(s):  
Nozomu Tominaga ◽  
Hideyuki Umeda ◽  
Keiichi Maeda ◽  
Ken'ichi Nomoto ◽  
Nobuyuki Iwamoto
Keyword(s):  
Early Universe ◽  
Chemical Evolution ◽  
Energy Deposition ◽  
Main Sequence ◽  
Metal Enrichment ◽  
Deposition Rates ◽  
Abundance Patterns ◽  
History Of ◽  
The Universe

AbstractThe first metal enrichment in the universe was made by supernova (SN) explosions of population (Pop) III stars. The history of chemical evolution is recorded in abundance patterns of extremely metal-poor (EMP) stars. We investigate the properties of nucleosynthesis in Pop III SNe by comparing their yields with the abundance patterns of the EMP stars. We focus on (1) jet-induced SNe with various properties of the jets, especially energy deposition rates [Ėdep = (0.3 − 1500) × 1051 ergs s−1], and (2) SNe of stars with various main-sequence masses (Mms = 13 − 50M⊙) and explosion energies [E = (1 − 40) × 1051ergs]. The varieties of Pop III SNe can explain the observations of the EMP stars: (1) higher [C/Fe] for lower [Fe/H] and (2) trends of abundance ratios [X/Fe] against [Fe/H].

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