Recent Developments in Cosmology
... (nearly infinite density and Temperature) beginning about 14 Billion years ago: ...
... (nearly infinite density and Temperature) beginning about 14 Billion years ago: ...
PH607lec07
... structure within the Milky Way that does not seem to fit within our current models. The collection of stars rises close to perpendicular to the plane of the spiral arms of the Milky Way. The proposed likely interpretation is that a dwarf galaxy is merging with the Milky Way. This galaxy is tenativel ...
... structure within the Milky Way that does not seem to fit within our current models. The collection of stars rises close to perpendicular to the plane of the spiral arms of the Milky Way. The proposed likely interpretation is that a dwarf galaxy is merging with the Milky Way. This galaxy is tenativel ...
superbubbles vs super-galactic winds
... superbubbles. These have often been mistaken with SGWs, despite their unique appearance which at all wavelengths is completely different to that presented by SGWs. Here we stress some of the main differences between SGWs and superbubbles and center our attention on three important issues: 1) The exp ...
... superbubbles. These have often been mistaken with SGWs, despite their unique appearance which at all wavelengths is completely different to that presented by SGWs. Here we stress some of the main differences between SGWs and superbubbles and center our attention on three important issues: 1) The exp ...
THE CHEMICAL COMPOSITION AND AGE OF THE METAL
... ultra–metal-poor halo stars (those with ½Fe=Hd 2:5, hereafter UMP stars). This technique has been used recently with Th (produced solely in the r-process), particularly with respect to the stable r-process element europium, in both halo field stars (S96; Cowan et al. 1997; Pfeiffer, Kratz, & Thiele ...
... ultra–metal-poor halo stars (those with ½Fe=Hd 2:5, hereafter UMP stars). This technique has been used recently with Th (produced solely in the r-process), particularly with respect to the stable r-process element europium, in both halo field stars (S96; Cowan et al. 1997; Pfeiffer, Kratz, & Thiele ...
The cosmic origin of fluorine and sulphur
... Practically only the two lightest elements, hydrogen and helium, were formed during the Big Bang when our Universe was born. All other elements have been formed, and keep being formed, in different processes in different types of stars. is means that all atoms, except hydrogen and helium, that build ...
... Practically only the two lightest elements, hydrogen and helium, were formed during the Big Bang when our Universe was born. All other elements have been formed, and keep being formed, in different processes in different types of stars. is means that all atoms, except hydrogen and helium, that build ...
Sample
... will interact with your body. Still smaller neutral particles called neutrinos, the most elusive yet most numerous and fastest of all particles, pass through us every moment. But they do so without consequence, for only very rarely, perhaps once or so per year, do any make a bull’s-eye collision wit ...
... will interact with your body. Still smaller neutral particles called neutrinos, the most elusive yet most numerous and fastest of all particles, pass through us every moment. But they do so without consequence, for only very rarely, perhaps once or so per year, do any make a bull’s-eye collision wit ...
The Structure of White Dwarf and Neutron Stars∗ Abstract
... Stars in their prime, while they are on the “main sequence,” support themselves against gravitational collapse by the pressure of hot gas, the energy being released in nuclear fusion reactions at the star’s core. For most of its life, the fusion reactions are dominated by protons (hydrogen nuclei) f ...
... Stars in their prime, while they are on the “main sequence,” support themselves against gravitational collapse by the pressure of hot gas, the energy being released in nuclear fusion reactions at the star’s core. For most of its life, the fusion reactions are dominated by protons (hydrogen nuclei) f ...
11.1 Introduction
... Despite such advances, star formation is still considered to be a poorlyunderstood problem in astrophysics. The reason is that we do not yet have a predictive theory of star formation; for example, given a set of initial conditions, we do not yet have the means to predict reliably important properti ...
... Despite such advances, star formation is still considered to be a poorlyunderstood problem in astrophysics. The reason is that we do not yet have a predictive theory of star formation; for example, given a set of initial conditions, we do not yet have the means to predict reliably important properti ...
Cosmology - 2015 - johndistefano.com.au
... The period when quarks became confined within hadrons – protons and neutrons- is known as the hadron 2 epoch. It started approximately 10−6 seconds after the Big Bang. Solitary neutrons decay into protons in about 15 minutes. So there was an interval of time from about 1 to 15 minutes in the age of ...
... The period when quarks became confined within hadrons – protons and neutrons- is known as the hadron 2 epoch. It started approximately 10−6 seconds after the Big Bang. Solitary neutrons decay into protons in about 15 minutes. So there was an interval of time from about 1 to 15 minutes in the age of ...
The title of my PDF
... (n, γ) and its inverse photo-dissociation (γ, n) with the much slower β-decays slowly building up each successive isotope. This picture holds true for most of the r-process; however, as the gas expands and cools, the photo-dissociation rates fall off very quickly with temperature. The neutron-captur ...
... (n, γ) and its inverse photo-dissociation (γ, n) with the much slower β-decays slowly building up each successive isotope. This picture holds true for most of the r-process; however, as the gas expands and cools, the photo-dissociation rates fall off very quickly with temperature. The neutron-captur ...
Cosmic Rays and Climate
... Understanding the cosmic ray climate link could have large implications in our understanding of climate changes and possible evolution on Earth. The evolution of the Milky Way and the Earth is linked ...
... Understanding the cosmic ray climate link could have large implications in our understanding of climate changes and possible evolution on Earth. The evolution of the Milky Way and the Earth is linked ...
Chemical analysis of 24 dusty (pre-) main
... in abundance analyses and the fairly high projected rotational velocities severely limit the amount of suitable lines. For a few slowly rotating stars (e.g. HD 18256, HD 20010, HD 104327 and HD 139614) we were able to use hundreds of lines in the analysis; the average value for the amount of lines i ...
... in abundance analyses and the fairly high projected rotational velocities severely limit the amount of suitable lines. For a few slowly rotating stars (e.g. HD 18256, HD 20010, HD 104327 and HD 139614) we were able to use hundreds of lines in the analysis; the average value for the amount of lines i ...
Nuclear Physics and Astrophysics
... Earth formed ~ 4.5 billion years ago Material rich in Fe, C, O, Si Heavier elements created in process of Nucleosynthesis from supernovae ...
... Earth formed ~ 4.5 billion years ago Material rich in Fe, C, O, Si Heavier elements created in process of Nucleosynthesis from supernovae ...
ASTRONOMY AND ASTROPHYSICS Barium and europium
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
On the origin of stars with and without planets
... either on the evolutionary stage of the star or on its age3 . In Fig. 1 we plot the T c slope against the stellar age. The plot and Table 1 clearly show that the correlation with age is quite significant and confirms the result obtained for the surface gravity: old stars are more depleted in refract ...
... either on the evolutionary stage of the star or on its age3 . In Fig. 1 we plot the T c slope against the stellar age. The plot and Table 1 clearly show that the correlation with age is quite significant and confirms the result obtained for the surface gravity: old stars are more depleted in refract ...
Barium and europium abundances in cool dwarf stars and
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
... Galactic interstellar gas. Overabundances of α-elements relative to iron observed in old stars argue in favour of this model (see the review of McWilliam 1997). Another argument can be obtained from observations of the heavy elements beyond the iron group. Abundances of these elements in the solar s ...
Richard Congdon. pdf
... Only a few of the elements in the universe were created at its beginning during the Big Bang, namely: hydrogen, deuterium, helium-3 and lithium (1H, 2H, 3He, 7Li). No further stable elements were created at this time because the rapid expansion and cooling, as the Universe expanded into of the void. ...
... Only a few of the elements in the universe were created at its beginning during the Big Bang, namely: hydrogen, deuterium, helium-3 and lithium (1H, 2H, 3He, 7Li). No further stable elements were created at this time because the rapid expansion and cooling, as the Universe expanded into of the void. ...
The Dark Age of the Universe
... overview of these events z ⬵ 1200. Later, when the first stars formed and emitted ionizing radiation, ionized regions formed around the sources will be described, with re- that eventually overlapped, filling all of space. The size of the HII regions should be much smaller on the redshift scale spect t ...
... overview of these events z ⬵ 1200. Later, when the first stars formed and emitted ionizing radiation, ionized regions formed around the sources will be described, with re- that eventually overlapped, filling all of space. The size of the HII regions should be much smaller on the redshift scale spect t ...
introduction - Wayne State University Physics and Astronomy
... Nucleosynthesis is the method where by nuclides heavier than that of Hydrogen are generated in celestial bodies. Neodymium (Nd) is a Rare-Earth lanthanide metal found in chemically peculiar (C.P.) stars, Gallium (Ga) is a heavy element (Z=31) also found in certain HgMn stars; these elements are of s ...
... Nucleosynthesis is the method where by nuclides heavier than that of Hydrogen are generated in celestial bodies. Neodymium (Nd) is a Rare-Earth lanthanide metal found in chemically peculiar (C.P.) stars, Gallium (Ga) is a heavy element (Z=31) also found in certain HgMn stars; these elements are of s ...
![[WC 6] nucleus with other emission-lines nuclei of planetary nebulae](http://s1.studyres.com/store/data/004159324_1-0806f9baff29e598ec0946db112c7fad-300x300.png)
[WC 6] nucleus with other emission-lines nuclei of planetary nebulae
... [WC]-type CSPN, 38 are assigned to a "weak emission-lines star" CSPN (wels) class, 2 are WN8 stars belonging most probably to pop.I WR stars (Tylenda et al, 1993) , and about 15 are of uncertain class. The [WC] nuclei mostly populate subclasses [WC 3-4] and [WC 9-11] whereas the Population I WC star ...
... [WC]-type CSPN, 38 are assigned to a "weak emission-lines star" CSPN (wels) class, 2 are WN8 stars belonging most probably to pop.I WR stars (Tylenda et al, 1993) , and about 15 are of uncertain class. The [WC] nuclei mostly populate subclasses [WC 3-4] and [WC 9-11] whereas the Population I WC star ...
Oxygen and Neon Abundances of B-Type Stars in Comparison with
... contradicting the Galactic chemical evolution, we carried out oxygen abundance determinations for 64 mid- through late-B stars by using the O I 6156–8 lines while taking into account the non-LTE effect, and compared them with the solar O abundance established in the same manner. The resulting mean o ...
... contradicting the Galactic chemical evolution, we carried out oxygen abundance determinations for 64 mid- through late-B stars by using the O I 6156–8 lines while taking into account the non-LTE effect, and compared them with the solar O abundance established in the same manner. The resulting mean o ...
Can We Travel to Other Stars?
... travel. Yet just such a path of speculation can help explain how intelligent life could have emerged in our galaxy without interstellar travel becoming commonplace. When SETI was first proposed, in a paper published in Nature by Giuseppe Cocconi and Philip Morrison in 1959, the main method of electr ...
... travel. Yet just such a path of speculation can help explain how intelligent life could have emerged in our galaxy without interstellar travel becoming commonplace. When SETI was first proposed, in a paper published in Nature by Giuseppe Cocconi and Philip Morrison in 1959, the main method of electr ...
Lecture 13 Presupernova Models, Core Collapse and Bounce
... It is now generally agreed (despite what you may read in old astronomy text books), that the so called prompt shock mechanism – worked on extensively by Bethe, Brown, Baron, Cooperstein, and colleagues in the 1980 s – does not work. The shock fails and becomes in a short time (< 10 ms) an accretion ...
... It is now generally agreed (despite what you may read in old astronomy text books), that the so called prompt shock mechanism – worked on extensively by Bethe, Brown, Baron, Cooperstein, and colleagues in the 1980 s – does not work. The shock fails and becomes in a short time (< 10 ms) an accretion ...
DOC
... detailed study of about 50 stars which are chosen for their diagnostic potential. The exploratory program will consist on a number of smaller observation runs, lasting 20 consecutive days, during which several tens of ...
... detailed study of about 50 stars which are chosen for their diagnostic potential. The exploratory program will consist on a number of smaller observation runs, lasting 20 consecutive days, during which several tens of ...
Nucleosynthesis
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons. The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis. It was then that hydrogen and helium formed to become the content of the first stars, and this primeval process is responsible for the present hydrogen/helium ratio of the cosmos.With the formation of stars, heavier nuclei were created from hydrogen and helium by stellar nucleosynthesis, a process that continues today. Some of these elements, particularly those lighter than iron, continue to be delivered to the interstellar medium when low mass stars eject their outer envelope before they collapse to form white dwarfs. The remains of their ejected mass form the planetary nebulae observable throughout our galaxy.Supernova nucleosynthesis within exploding stars by fusing carbon and oxygen is responsible for the abundances of elements between magnesium (atomic number 12) and nickel (atomic number 28). Supernova nucleosynthesis is also thought to be responsible for the creation of rarer elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons (the R process) in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived elements uranium and thorium.Cosmic ray spallation, caused when cosmic rays impact the interstellar medium and fragment larger atomic species, is a significant source of the lighter nuclei, particularly 3He, 9Be and 10,11B, that are not created by stellar nucleosynthesis.In addition to the fusion processes responsible for the growing abundances of elements in the universe, a few minor natural processes continue to produce very small numbers of new nuclides on Earth. These nuclides contribute little to their abundances, but may account for the presence of specific new nuclei. These nuclides are produced via radiogenesis (decay) of long-lived, heavy, primordial radionuclides such as uranium and thorium. Cosmic ray bombardment of elements on Earth also contribute to the presence of rare, short-lived atomic species called cosmogenic nuclides.