scholarly journals The Light Elements: What is Known, What is Controversial

2000 ◽  
Vol 198 ◽  
pp. 3-10 ◽  
Author(s):  
F. Spite
Keyword(s):  
Big Bang ◽  
Stellar Atmospheres ◽  
Stellar Structure ◽  
H Ii Regions ◽  
Light Elements ◽  
Stellar Abundances ◽  
Stellar Interiors ◽  
The Big Bang ◽  
The Universe

The light elements are essential, because their primordial abundances are linked to the general parameters of the universe (at least in the Big Bang theory). Some of the light elements are fragile, and the interpretation of their abundances in stars requires a good knowledge of the stellar structure. The stellar abundances have to be known with a considerable accuracy, challenging the current level of representation of the stellar atmospheres. It is also difficult to reach accurate abundances in the gas : interstellar, H II regions, PN, intergalactic¨.On the other hand, the fragile light elements are important probes of the stellar interiors, and their observation helps to the determination of reliable models, which in turn will improve the accuracy of stellar abundances. A part of this symposium is devoted to this probing aspect.The talks (and many high quality posters) which build this symposium, cover all these aspects. I will try here to point out the controversial points and the reasonably well known facts. We expect from discussions, both formal and informal, a number of (eagerly awaited for) clarifications.

scholarly journals Joint Discussion 10: 3D views on cool stellar atmospheres – theory meets observation

2009 ◽  
Vol 5 (H15) ◽  
pp. 331-343
Author(s):  
K.N. Nagendra ◽  
P. Bonifacio ◽  
H.-G. Ludwig
Keyword(s):  
Chemical Composition ◽  
High Efficiency ◽  
Big Bang ◽  
Stellar Atmosphere ◽  
Stellar Atmospheres ◽  
Stellar Spectra ◽  
Low Mass ◽  
Computational Resources ◽  
The Big Bang ◽  
The Universe

Much of what we know about the chemical composition of the Universe actually stems from the chemical composition of stars, which is often deciphered from the spectra emerging from their atmospheres. Cool, low-mass and long-living stars allow to study the evolution of the Universe's chemistry from a time shortly after the big bang until today. The observation and interpretation of stellar spectra is a classical field in astronomy but is still undergoing vivid developments. The enormous increase in available computational resources opened-up possibilities which led to a revolution in the degree of realism to which modelers can mimic Nature. High-resolution, high-stability, high-efficiency spectrographs are now routinely providing stellar spectra whose full information content can only be exploited if a very much refined description of a stellar atmosphere is at hand.

scholarly journals Light Elements in the Universe

2021 ◽  
Vol 8 ◽  
Author(s):  
Sofia Randich ◽  
Laura Magrini
Keyword(s):  
Globular Clusters ◽  
Light Element ◽  
Big Bang ◽  
Stellar Structure ◽  
Age Dating ◽  
Sequence Evolution ◽  
Light Elements ◽  
Chemical Enrichment ◽  
Star Formation Histories ◽  
The Universe

Due to their production sites, as well as to how they are processed and destroyed in stars, the light elements are excellent tools to investigate a number of crucial issues in modern astrophysics: from stellar structure and non-standard processes at work in stellar interiors to age dating of stars; from pre-main sequence evolution to the star formation histories of young clusters and associations and to multiple populations in globular clusters; from Big Bang nucleosynthesis to the formation and chemical enrichment history of the Milky Way Galaxy and its populations, just to cite some relevant examples. In this paper, we focus on lithium, beryllium, and boron (LiBeB) and on carbon, nitrogen, and oxygen (CNO). LiBeB are rare elements, with negligible abundances with respect to hydrogen; on the contrary, CNO are among the most abundant elements in the Universe, after H and He. Pioneering observations of light-element surface abundances in stars started almost 70 years ago and huge progress has been achieved since then. Indeed, for different reasons, precise measurements of LiBeB and CNO are difficult, even in our Sun; however, the advent of state-of-the-art ground- and space-based instrumentation has allowed the determination of high-quality abundances in stars of different type, belonging to different Galactic populations, from metal-poor halo stars to young stars in the solar vicinity and from massive stars to cool dwarfs and giants. Noticeably, the recent large spectroscopic surveys performed with multifiber spectrographs have yielded detailed and homogeneous information on the abundances of Li and CNO for statistically significant samples of stars; this has allowed us to obtain new results and insights and, at the same time, raise new questions and challenges. A complete understanding of the light-element patterns and evolution in the Universe has not been still achieved. Perspectives for further progress will open up soon thanks to the new generation instrumentation that is under development and will come online in the coming years.

scholarly journals THE CMB DIPOLE AND CIRCULAR GALAXY DISTRIBUTION

2007 ◽  
Vol 22 (21) ◽  
pp. 1553-1567 ◽  
Author(s):  
YUKIO TOMOZAWA
Keyword(s):  
Mass Distribution ◽  
Big Bang ◽  
Tidal Force ◽  
Galaxy Distribution ◽  
Special Direction ◽  
Hubble’S Law ◽  
The Big Bang ◽  
The Universe ◽  
Hubble Flow

The validity of Hubble's law defies the determination of the center of the big bang expansion, even if it exists. Every point in the expanding universe looks like the center from which the rest of the universe flies away. In this paper, we show that the distri- bution of apparently circular galaxies is not uniform in the sky and that there exists a special direction in the universe in our neighborhood. The data is consistent with the assumption that the tidal force due to the mass distribution around the universe center causes the deformation of galactic shapes depending on its orientation and location relative to the center and our galaxy. Moreover, the CMB dipole data can also be associated with the center of the universe expansion, if the CMB dipole at the center of our supercluster is assumed to be due to Hubble flow. The location of the center is estimated from the CMB dipole data. The direction to the center from both sets of data is consistent and the distance to the center is computed from the CMB dipole data.

8. Where do the elements come from?

2019 ◽  
pp. 117-131
Author(s):  
Geoff Cottrell
Keyword(s):  
Neutron Stars ◽  
Chemical Elements ◽  
Big Bang ◽  
Life Cycles ◽  
Light Elements ◽  
Hydrogen Atoms ◽  
The Big Bang ◽  
The Universe ◽  
Made In

To understand where the chemical elements came from, we look at the earliest moments of the universe. ‘Where do the elements come from?’ traces the evolution of all the matter and energy in the universe, starting from a fraction of a second after its birth in the ‘Big Bang’, 13.8 billion years ago. The light elements, for example the hydrogen atoms in your body, were made in the Big Bang. The middleweight elements, such as carbon and oxygen, were (and still are being) forged deep inside stars, while the heavyweight elements, like gold and platinum, were produced in violent stellar explosions. The life cycles of stars, including supernovae, neutron stars, and pulsars is outlined.

scholarly journals Insights Into Chemical Reactions at the Beginning of the Universe: From HeH+ to H3+

2021 ◽  
Vol 9 ◽  
Author(s):  
Soumya Ranjan Dash ◽  
Tamal Das ◽  
Kumar Vanka
Keyword(s):  
Big Bang ◽  
Light Elements ◽  
Hydrogen Atoms ◽  
Big Bang Nucleosynthesis ◽  
Special Cases ◽  
The Big Bang ◽  
The Universe ◽  
Dynamics Method ◽  
Positively Charged ◽  
Dense Atmosphere

At the dawn of the Universe, the ions of the light elements produced in the Big Bang nucleosynthesis recombined with each other. In our present study, we have tried to mimic the conditions in the early Universe to show how the recombination process would have led to the formation of the first ever formed diatomic species of the Universe: HeH+, as well as the subsequent processes that would have led to the formation of the simplest triatomic species: H3+. We have also studied some special cases: higher positive charge with fewer number of hydrogen atoms in a dense atmosphere, and the formation of unusual and interesting linear, dicationic He chains beginning from light elements He and H in a positively charged atmosphere. For all the simulations, the ab initio nanoreactor (AINR) dynamics method has been employed.

A view of the universe before the big bang

2006 ◽  
Vol 190 ◽  
pp. 15-15
Author(s):  
D CASTELVECCHI
Keyword(s):  
Big Bang ◽  
The Big Bang ◽  
The Universe

The Planet in a Pebble

2010 ◽  
Author(s):  
Jan Zalasiewicz
Keyword(s):  
Solar System ◽  
Volcanic Eruptions ◽  
Big Bang ◽  
Forensic Analysis ◽  
Mineral Matter ◽  
Supernova Explosions ◽  
Deep Underground ◽  
The Big Bang ◽  
The Universe

This is the story of a single pebble. It is just a normal pebble, as you might pick up on holiday - on a beach in Wales, say. Its history, though, carries us into abyssal depths of time, and across the farthest reaches of space. This is a narrative of the Earth's long and dramatic history, as gleaned from a single pebble. It begins as the pebble-particles form amid unimaginable violence in distal realms of the Universe, in the Big Bang and in supernova explosions and continues amid the construction of the Solar System. Jan Zalasiewicz shows the almost incredible complexity present in such a small and apparently mundane object. Many events in the Earth's ancient past can be deciphered from a pebble: volcanic eruptions; the lives and deaths of extinct animals and plants; the alien nature of long-vanished oceans; and transformations deep underground, including the creations of fool's gold and of oil. Zalasiewicz demonstrates how geologists reach deep into the Earth's past by forensic analysis of even the tiniest amounts of mineral matter. Many stories are crammed into each and every pebble around us. It may be small, and ordinary, this pebble - but it is also an eloquent part of our Earth's extraordinary, never-ending story.

scholarly journals Relativistic Cosmology with an Introduction to Inflation

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 276
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis García Guirao
Keyword(s):  
Standard Model ◽  
Early Universe ◽  
Large Scale ◽  
Initial Conditions ◽  
Big Bang ◽  
Relativistic Cosmology ◽  
The Standard Model ◽  
Big Bang Model ◽  
The Big Bang ◽  
The Universe

In this review article, the study of the development of relativistic cosmology and the introduction of inflation in it as an exponentially expanding early phase of the universe is carried out. We study the properties of the standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. The geometric properties of space and spacetime ingrained into the standard model of cosmology are investigated in addition. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. The cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe. Further inflation and dark energy in fR modified gravity are also reviewed.

scholarly journals Dynamo effects in gravity

2019 ◽  
Vol 127 ◽  
pp. 02009
Author(s):  
Boris Shevtsov
Keyword(s):  
Gravitational Constant ◽  
Nonlinear Oscillations ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
System Of Equations ◽  
Fractal Structures ◽  
Expansion Of The Universe ◽  
The Big Bang ◽  
The Universe ◽  
Made In

Nonlinear oscillations in the dynamic system of gravitational and material fields are considered. The problems of singularities and caustics in gravity, expansion and baryon asymmetry of the Universe, wave prohibition of collapse into black holes, and failure of the Big Bang concept are discussed. It is assumed that the effects of the expansion of the Universe are coupling with the reverse collapse of dark matter. This hypothesis is used to substantiate the vortex and fractal structures in the distribution of matter. A system of equations is proposed for describing turbulent and fluctuation processes in gravitational and material fields. Estimates of the di usion parameters of such a system are made in comparison with the gravitational constant.

A swift and simple refutation of the Kalam cosmological argument?

1999 ◽  
Vol 35 (1) ◽  
pp. 57-72 ◽  
Author(s):  
WILLIAM LANE CRAIG
Keyword(s):  
Big Bang ◽  
Cosmological Argument ◽  
Convincing Argument ◽  
Realist Position ◽  
Big Bang Theory ◽  
Simple Demonstration ◽  
Kalam Cosmological Argument ◽  
John Taylor ◽  
The Big Bang ◽  
The Universe

John Taylor complains that the Kalam cosmological argument gives the appearance of being a swift and simple demonstration of the existence of a Creator of the universe, whereas in fact a convincing argument involving the premiss that the universe began to exist is very difficult to achieve. But Taylor's proffered defeaters of the premisses of the philosophical arguments for the beginning of the universe are themselves typically undercut due to Taylor's inadvertence to alternatives open to the defender of the Kalam arguments. With respect to empirical confirmation of the universe's beginning Taylor is forced into an anti-realist position on the Big Bang theory, but without sufficient warrant for singling out the theory as non-realistic. Therefore, despite the virtue of simplicity of form, the Kalam cosmological argument has not been defeated by Taylor's all too swift refutation.

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