arXiv:astro-ph/0612072v1 4 Dec 2006 Theory of core
... core collapse and supernova explosions on the one hand, and in the description of the microphysics input of such models on the other, since Hans Bethe published his grand review article in 1990 [1]. The field is very broad and has experienced also a great expansion after long-soft gamma-ray bursts h ...
... core collapse and supernova explosions on the one hand, and in the description of the microphysics input of such models on the other, since Hans Bethe published his grand review article in 1990 [1]. The field is very broad and has experienced also a great expansion after long-soft gamma-ray bursts h ...
The Black Hole at the Beginning of Time
... energy. We imagine that, shortly after the big bang, the uni- nuclear fusion powers a star for most of its life, but eventually verse was filled with energy that takes the form of a hypotheti- the star exhausts all its nuclear fuel, and gravity takes over. A cal particle called the inflaton (pronoun ...
... energy. We imagine that, shortly after the big bang, the uni- nuclear fusion powers a star for most of its life, but eventually verse was filled with energy that takes the form of a hypotheti- the star exhausts all its nuclear fuel, and gravity takes over. A cal particle called the inflaton (pronoun ...
lecture27
... have determined whether a galaxy ended up as a spiral galaxy with a gaseous disk or as an elliptical galaxy without a disk. (1) Angular momentum tends to shape a collapsing gas cloud into a spinning disk. Thus, ellipticals may have formed from protogalactic clouds with relatively small amounts of an ...
... have determined whether a galaxy ended up as a spiral galaxy with a gaseous disk or as an elliptical galaxy without a disk. (1) Angular momentum tends to shape a collapsing gas cloud into a spinning disk. Thus, ellipticals may have formed from protogalactic clouds with relatively small amounts of an ...
Power-point slides for Lecture 1
... • Nebular spectrum at late times dominated by Fe II, III, Co II, III • Found in all kinds of galaxies, elliptical to spiral, some (controversial) evidence for a mild association with spiral arms ...
... • Nebular spectrum at late times dominated by Fe II, III, Co II, III • Found in all kinds of galaxies, elliptical to spiral, some (controversial) evidence for a mild association with spiral arms ...
The Evolution of Isotope Ratios in the Milky Way Galaxy
... Super AGB stars — The fate of stars with initial masses between about 8 − 10M⊙ is uncertain. The upper limit of AGB stars, Mu,1 , is defined as the minimum mass for carbon ignition, and is estimated to be larger at high metallicity and also at low metallicity than at Z ∼ 10−4 (Gil-Pons et al. 2007; ...
... Super AGB stars — The fate of stars with initial masses between about 8 − 10M⊙ is uncertain. The upper limit of AGB stars, Mu,1 , is defined as the minimum mass for carbon ignition, and is estimated to be larger at high metallicity and also at low metallicity than at Z ∼ 10−4 (Gil-Pons et al. 2007; ...
Cosmology
... Cosmic background radiation is the afterglow of the Big Bang • The cosmic microwave background radiation, corresponding to a temperature of 2.7 K at the present day, is the greatly redshifted remnant of the hot universe as it existed about 380,000 years after the Big Bang • During the first 380,000 ...
... Cosmic background radiation is the afterglow of the Big Bang • The cosmic microwave background radiation, corresponding to a temperature of 2.7 K at the present day, is the greatly redshifted remnant of the hot universe as it existed about 380,000 years after the Big Bang • During the first 380,000 ...
TO THE STATISTICS OF DOUBLE STARS It was indicated by a
... It was indicated by a number of authors, that the study of distribution law of elements of double stars orbits, as well as of other statistical interrelations for these objects, can give interesting results for cosmogony in general and for the age problem of our star system in particular. However, a ...
... It was indicated by a number of authors, that the study of distribution law of elements of double stars orbits, as well as of other statistical interrelations for these objects, can give interesting results for cosmogony in general and for the age problem of our star system in particular. However, a ...
Chemical composition of 90 F and G disk dwarfs
... that the products of supernovae of different types are thoroughly mixed into the interstellar medium (ISM) before significant star formation occurs. Based on this, the large scatter in [Fe/H] may be explained by infall of unprocessed gas with a characteristic mixing time much longer than that of the ...
... that the products of supernovae of different types are thoroughly mixed into the interstellar medium (ISM) before significant star formation occurs. Based on this, the large scatter in [Fe/H] may be explained by infall of unprocessed gas with a characteristic mixing time much longer than that of the ...
A comparison of the s- and r-process element evolution in local
... formation and evolution. Methods. We compare the evolution of [Ba/Fe], [Eu/Fe], [La/Fe], [Y/Fe], [Ba/Y], [Ba/Eu], [Y/Eu], and [La/Eu] observed in dSph galaxies and in our Galaxy with predictions of detailed chemical evolution models. The models for all dSph galaxies and for the Milky Way are able to ...
... formation and evolution. Methods. We compare the evolution of [Ba/Fe], [Eu/Fe], [La/Fe], [Y/Fe], [Ba/Y], [Ba/Eu], [Y/Eu], and [La/Eu] observed in dSph galaxies and in our Galaxy with predictions of detailed chemical evolution models. The models for all dSph galaxies and for the Milky Way are able to ...
Precision Measurement of Transition Matrix Elements via Light Shift
... initially stationary atoms, the |l| = 1 orders are equivalent and can be represented as a single state, which along with the l = 0 state are the two poles of the Bloch sphere. Free evolution corresponds to precession about the vertical axis with period h/(4ER ), called the Talbot time [31]. During a ...
... initially stationary atoms, the |l| = 1 orders are equivalent and can be represented as a single state, which along with the l = 0 state are the two poles of the Bloch sphere. Free evolution corresponds to precession about the vertical axis with period h/(4ER ), called the Talbot time [31]. During a ...
atmospheric extinction
... Neutral gas in our Galaxy absorbs thru photoelectric effect. This is predominantly neutral hydrogen (HI): the Lyman limit occurs at 912 Å = 13.6 eV At frequencies higher than 13.6 eV part of the X-ray flux is Absorbed, in a frequency-dependent way Morrison & McCammon (1983, ApJ, 270, 119) have comp ...
... Neutral gas in our Galaxy absorbs thru photoelectric effect. This is predominantly neutral hydrogen (HI): the Lyman limit occurs at 912 Å = 13.6 eV At frequencies higher than 13.6 eV part of the X-ray flux is Absorbed, in a frequency-dependent way Morrison & McCammon (1983, ApJ, 270, 119) have comp ...
Evolution of the barium abundance in the early Galaxy from a NLTE
... levels and overpopulates the upper ones (this “pumping” is described e.g. in Bruls et al. 1992, or Asplund 2005). The depth of the effective formation of the radiation in b-b transitions changes significantly with the metallicity (and the corresponding barium abundance) of the star (Fig. 3). This exp ...
... levels and overpopulates the upper ones (this “pumping” is described e.g. in Bruls et al. 1992, or Asplund 2005). The depth of the effective formation of the radiation in b-b transitions changes significantly with the metallicity (and the corresponding barium abundance) of the star (Fig. 3). This exp ...
Lecture notes 8
... Average must be taken over the orbital energies to allow for the possible partitioning of the atom’s electrons among its orbitals. This is done by calculating the partition function, Z, for the initial and final atoms. Z is the weighted sum of the number of ways the atom can arrange its electrons wi ...
... Average must be taken over the orbital energies to allow for the possible partitioning of the atom’s electrons among its orbitals. This is done by calculating the partition function, Z, for the initial and final atoms. Z is the weighted sum of the number of ways the atom can arrange its electrons wi ...
Carbon-enhanced metal-poor stars: a window on AGB
... Many of the carbon-enhanced metal-poor (CEMP) stars that we observe in the Galactic halo are found in binary systems and show enhanced abundances of elements produced by the slow neutron-capture process (s-elements). The origin of the peculiar chemical abundances of these CEMP-s stars is believed to ...
... Many of the carbon-enhanced metal-poor (CEMP) stars that we observe in the Galactic halo are found in binary systems and show enhanced abundances of elements produced by the slow neutron-capture process (s-elements). The origin of the peculiar chemical abundances of these CEMP-s stars is believed to ...
Neutron Stars - Lick Observatory
... Neutron stars are small compact stars with densities comparable to that inside nuclei, !0 = 2.8 × 1014 g cm!3, and radii R ! 10–15 km. They consist predominantly of NEUTRONS and a few percent of PROTONS and ELECTRONS. These huge neutron-rich ‘nuclei’ are bound by gravitation and require a minimum ne ...
... Neutron stars are small compact stars with densities comparable to that inside nuclei, !0 = 2.8 × 1014 g cm!3, and radii R ! 10–15 km. They consist predominantly of NEUTRONS and a few percent of PROTONS and ELECTRONS. These huge neutron-rich ‘nuclei’ are bound by gravitation and require a minimum ne ...
4. Star Formation
... The Initial Mass Function and binary frequency of stars can as well be reproduced by the models. Mass accretion rates are time varying and strongly influenced by the cluster environment. Star formation is a highly stochastic process !!! ...
... The Initial Mass Function and binary frequency of stars can as well be reproduced by the models. Mass accretion rates are time varying and strongly influenced by the cluster environment. Star formation is a highly stochastic process !!! ...
ChESS: ChaMP Extended Stellar Survey
... LX : Median oronal X-ray luminosity for main-sequen e spe tral types; ...
... LX : Median oronal X-ray luminosity for main-sequen e spe tral types; ...
Chapter 5 Nuclear reactions in stars
... a star. By putting these ingredients together we can construct models of spherically symmetric stars. Because the complete set of equations is highly non-linear and time-dependent, their full solution requires a complicated numerical procedure. This is what is done in detailed stellar evolution code ...
... a star. By putting these ingredients together we can construct models of spherically symmetric stars. Because the complete set of equations is highly non-linear and time-dependent, their full solution requires a complicated numerical procedure. This is what is done in detailed stellar evolution code ...
Document
... – Take into account: – two p-p fusions per branch – weightings of each branch – 15 MeV per p-p fusion – Given number of fusions per m-3 calculated earlier, energy production rate ~ 120 Wm-3 ...
... – Take into account: – two p-p fusions per branch – weightings of each branch – 15 MeV per p-p fusion – Given number of fusions per m-3 calculated earlier, energy production rate ~ 120 Wm-3 ...
A massive hypergiant star as the progenitor of the supernova SN
... Magellanic Cloud—has a star been detected at the supernova location before the explosion, and been subsequently shown to have vanished after the supernova event1. The progenitor of SN 1987A was a blue supergiant, which required a rethink of stellar evolution models2. The progenitor of supernova SN 2 ...
... Magellanic Cloud—has a star been detected at the supernova location before the explosion, and been subsequently shown to have vanished after the supernova event1. The progenitor of SN 1987A was a blue supergiant, which required a rethink of stellar evolution models2. The progenitor of supernova SN 2 ...
REVIEWS The formation of the first stars and galaxies Volker Bromm
... which posits that structure grew hierarchically, such that small objects formed first and then merged to form increasingly larger systems6. Within this model, dark-matter ‘minihaloes’ (see below), forming a few hundred million years after the Big Bang, were identified as the sites where the first st ...
... which posits that structure grew hierarchically, such that small objects formed first and then merged to form increasingly larger systems6. Within this model, dark-matter ‘minihaloes’ (see below), forming a few hundred million years after the Big Bang, were identified as the sites where the first st ...
Lithium abundances for 185 main-sequence stars
... Before adopting this explanation we should, however, be able to explain why stars with [Fe/H] > ∼ −1.4 have such a large dispersion of their Li abundances. Furthermore, it is not clear if stars along the upper envelope have retained their original Li abundances or suffered a mild degree of Li deplet ...
... Before adopting this explanation we should, however, be able to explain why stars with [Fe/H] > ∼ −1.4 have such a large dispersion of their Li abundances. Furthermore, it is not clear if stars along the upper envelope have retained their original Li abundances or suffered a mild degree of Li deplet ...
The 100-billion-body problem A full-scale computer simulation of the
... from O(N 2 ) to O(N log N), a huge improvement. For 1011 stars, the number of force evaluations per time step falls from 1022 to as few as 1013. The tradeoff between speed and accuracy can be fine-tuned by adjusting the crossover point between individual and aggregated force computations. To observe ...
... from O(N 2 ) to O(N log N), a huge improvement. For 1011 stars, the number of force evaluations per time step falls from 1022 to as few as 1013. The tradeoff between speed and accuracy can be fine-tuned by adjusting the crossover point between individual and aggregated force computations. To observe ...
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.