Chapter 15
... • Despite uncertainties, the basic idea of the initial stars being made of pure hydrogen and helium is still true – so where are they • These population III stars may not be observable for three reasons – Only short-lived massive population III stars can form – consequently none are left today – Pop ...
... • Despite uncertainties, the basic idea of the initial stars being made of pure hydrogen and helium is still true – so where are they • These population III stars may not be observable for three reasons – Only short-lived massive population III stars can form – consequently none are left today – Pop ...
Cosmology * The Origin and Evolution of the Universe
... Density Possessed by Space Itself? • Yes – the Casimir Effect • Predicted by the Dutch physicist Hendrick Casimir in 1948. According to quantum theory, the vacuum contains virtual particles which are in a continuous state of fluctuation (see physics FAQ article on virtual particles). Casimir realise ...
... Density Possessed by Space Itself? • Yes – the Casimir Effect • Predicted by the Dutch physicist Hendrick Casimir in 1948. According to quantum theory, the vacuum contains virtual particles which are in a continuous state of fluctuation (see physics FAQ article on virtual particles). Casimir realise ...
Stellar Populations For many modern applications, one is not
... The above analytic solutions are only useful for guidance. To compare with observations, predictions must be made in specific bandpasses, or for specific absorption lines. This requires numerical calculations which include 1) sets of stellar isochrones, detailing the precise number of stars at any p ...
... The above analytic solutions are only useful for guidance. To compare with observations, predictions must be made in specific bandpasses, or for specific absorption lines. This requires numerical calculations which include 1) sets of stellar isochrones, detailing the precise number of stars at any p ...
Element Segregation in Low Metallicity Stars and the Primordial
... star. This result leads to the idea that the observed lithium abundances may be related to this maximum value. When VC95 computed the effect of mass loss on the lithium abundances in Pop II stars, they found the following characteristic behavior : for very small mass loss rates, the surface lithium ...
... star. This result leads to the idea that the observed lithium abundances may be related to this maximum value. When VC95 computed the effect of mass loss on the lithium abundances in Pop II stars, they found the following characteristic behavior : for very small mass loss rates, the surface lithium ...
Chapter 15 Stars, Galaxies, and Universe Galaxies
... nearby stars (within a few hundred light years, that is). ...
... nearby stars (within a few hundred light years, that is). ...
Chapter 17--Star Stuff
... The length of time from the formation of a protostar to the birth of a main-sequence star depends on the star’s mass. Massive stars do everything faster. The contraction of a high-mass protostar into a main-sequence star may take only a million years or less. A star like our Sun takes about 50 milli ...
... The length of time from the formation of a protostar to the birth of a main-sequence star depends on the star’s mass. Massive stars do everything faster. The contraction of a high-mass protostar into a main-sequence star may take only a million years or less. A star like our Sun takes about 50 milli ...
Chpt17-18
... The expanding universe also caused the wavelengths of radiation from the Big Bang to be red shifted. We see this today as the microwave background radiation. ...
... The expanding universe also caused the wavelengths of radiation from the Big Bang to be red shifted. We see this today as the microwave background radiation. ...
W. M. White Geochemistry Chapter 10: Cosmochemistry
... the cosmos by looking at old stars. The old stars of Population II are considerably poorer in heavy elements than are young stars. In particular, Population II stars have a Fe/H ratio typically a factor of 100 lower than the Sun. This suggests that much of the heavy element inventory of the galaxy h ...
... the cosmos by looking at old stars. The old stars of Population II are considerably poorer in heavy elements than are young stars. In particular, Population II stars have a Fe/H ratio typically a factor of 100 lower than the Sun. This suggests that much of the heavy element inventory of the galaxy h ...
... • Despite uncertainties, the basic idea of the initial stars being made of pure hydrogen and helium is still true – so where are they • These population III stars may not be observable for three reasons – Only short-lived massive population III stars can form – consequently none are left today – Pop ...
ppt - ciera
... fields reveals no new 530 s pulsars, so there is a <0.5% chance of finding a magnetar in any field (Nechita, Gaensler, Muno, et al. in prep). • The pulsar is well within the cluster, with a <10% chance of being an unrelated X-ray source. ...
... fields reveals no new 530 s pulsars, so there is a <0.5% chance of finding a magnetar in any field (Nechita, Gaensler, Muno, et al. in prep). • The pulsar is well within the cluster, with a <10% chance of being an unrelated X-ray source. ...
Lecture 15
... night sky, stars are very far apart from each other – Remember that the next closest star to the Sun is 4.3 light-years – That’s 25 trillion miles! ...
... night sky, stars are very far apart from each other – Remember that the next closest star to the Sun is 4.3 light-years – That’s 25 trillion miles! ...
Spectral line mapping of the Milky Way
... are good tracers of molecular gas (under different density and excitation conditions), and have provided fundamental insights in the processes of star formation [21]. On the other hand, maser emission from different molecules (OH, SiO, CH3 OH, H2 O) are useful signposts of energetic phenomena in the ...
... are good tracers of molecular gas (under different density and excitation conditions), and have provided fundamental insights in the processes of star formation [21]. On the other hand, maser emission from different molecules (OH, SiO, CH3 OH, H2 O) are useful signposts of energetic phenomena in the ...
ASTR 001 Introduction to the Cosmos
... the universe? A) 4 percent B) 10 percent C) 25 percent D) 50 percent 18. Based on inventoried matter in the universe, including dark matter known to exist in galaxies and clusters, the actual matter density of the universe is what fraction of the critical density? A) 1 percent B) 10 percent C) 30 pe ...
... the universe? A) 4 percent B) 10 percent C) 25 percent D) 50 percent 18. Based on inventoried matter in the universe, including dark matter known to exist in galaxies and clusters, the actual matter density of the universe is what fraction of the critical density? A) 1 percent B) 10 percent C) 30 pe ...
L133 VERY LARGE TELESCOPE SPECTRA OF CARBON STARS
... In general, stars are oxygen-rich when they enter the AGB phase. Third dredge-up leads to 12C enrichment in the atmospheres of AGB stars. If the C/O ratio exceeds unity after the third dredge-up, the star is classified as a carbon star. Theoretical models have predicted that the amount of 12C enrich ...
... In general, stars are oxygen-rich when they enter the AGB phase. Third dredge-up leads to 12C enrichment in the atmospheres of AGB stars. If the C/O ratio exceeds unity after the third dredge-up, the star is classified as a carbon star. Theoretical models have predicted that the amount of 12C enrich ...
Astroparticle physics A.M. van den Berg () O. Scholten
... - Universe is hot, expanding plasma of radiation & relativistic particles - roughly equal # electrons, positrons, (anti)neutrinos, and photons - nucleons outnumbered by more than a billion to one ...
... - Universe is hot, expanding plasma of radiation & relativistic particles - roughly equal # electrons, positrons, (anti)neutrinos, and photons - nucleons outnumbered by more than a billion to one ...
11 Solar Masses
... MHC and is more conducive to explosion. Less electron capture, less neutrino escape, larger initial Ye could raise YL. ...
... MHC and is more conducive to explosion. Less electron capture, less neutrino escape, larger initial Ye could raise YL. ...
Name - MIT
... 4) The two most abundant elements in our Galaxy are? A) oxygen and carbon. B) hydrogen and helium. C) iron and hydrogen. D) carbon and iron. E) iron and helium. 5) The two most abundant elements in the Universe are? A) oxygen and carbon. B) iron and hydrogen. C) hydrogen and helium. D) carbon and ir ...
... 4) The two most abundant elements in our Galaxy are? A) oxygen and carbon. B) hydrogen and helium. C) iron and hydrogen. D) carbon and iron. E) iron and helium. 5) The two most abundant elements in the Universe are? A) oxygen and carbon. B) iron and hydrogen. C) hydrogen and helium. D) carbon and ir ...
Name - MIT
... 21) Supermassive ___________________ are thought to be at the centers of active galactic nuclei and be the source of power for the tremendous amounts of energy they release. A) B) C) D) E) ...
... 21) Supermassive ___________________ are thought to be at the centers of active galactic nuclei and be the source of power for the tremendous amounts of energy they release. A) B) C) D) E) ...
Name
... 29) Why should you be able to determine the distance to a star with a spectral type of G2 in our galaxy? A) All G2 stars are at same distance to Earth B) The period of their variability is proportional to their distance from Earth C) G2 stars have similar luminosities to our Sun, which can be used t ...
... 29) Why should you be able to determine the distance to a star with a spectral type of G2 in our galaxy? A) All G2 stars are at same distance to Earth B) The period of their variability is proportional to their distance from Earth C) G2 stars have similar luminosities to our Sun, which can be used t ...
Problem Set 2 for Astro 322 Read chapter 24.2. (Some of this
... I(R = 8kpc) = I(R = 0)exp(−8/4) = 20.2 L pc−2 . We note that this M/LV ratio is integrated over all z, through the thick disk as well as the thin. The thick disk (due to its age) has no massive stars, so its M/LV ratio is rather higher than the ratio for stars near the Sun at the midplane, which in ...
... I(R = 8kpc) = I(R = 0)exp(−8/4) = 20.2 L pc−2 . We note that this M/LV ratio is integrated over all z, through the thick disk as well as the thin. The thick disk (due to its age) has no massive stars, so its M/LV ratio is rather higher than the ratio for stars near the Sun at the midplane, which in ...
Presolar History Recorded in Extraterrestrial Materials
... enormous number of Solar System grains of similar mineralogy. Indeed, the main component of meteorites and interplanetary dust particles (IDPs) are silicates that formed in the early solar nebula. The small size of presolar silicates, just a few hundred nanometers on average, made their detection ev ...
... enormous number of Solar System grains of similar mineralogy. Indeed, the main component of meteorites and interplanetary dust particles (IDPs) are silicates that formed in the early solar nebula. The small size of presolar silicates, just a few hundred nanometers on average, made their detection ev ...
Presentazione di PowerPoint
... in clusters which do not have any dispersion in [Fe/H] and Fe peak elements Some of these abundance spreads are present also at the level of main sequence and subgiant branch stars, which gives strong support to the idea that they could be primordial. (from Carretta et al. 2006, A&A, 450, 523) ...
... in clusters which do not have any dispersion in [Fe/H] and Fe peak elements Some of these abundance spreads are present also at the level of main sequence and subgiant branch stars, which gives strong support to the idea that they could be primordial. (from Carretta et al. 2006, A&A, 450, 523) ...
The Voronoi tessellation generated from different
... analyzed the puzzle of the periodic walls that characterize the galaxy distribution in the universe. In a recent beam pencil survey along the galactic poles peaks appear when the number of pairings of galaxies at a particular distance apart is plotted against the distance between them (see ref. [ 9 ...
... analyzed the puzzle of the periodic walls that characterize the galaxy distribution in the universe. In a recent beam pencil survey along the galactic poles peaks appear when the number of pairings of galaxies at a particular distance apart is plotted against the distance between them (see ref. [ 9 ...
Our Expanding Universe
... The Big Bang Theory Cosmologists—people who study the components, evolution, and physics of the entire Universe—now believe that all matter and energy in the Universe expanded from a point that was smaller than the period at the end of this sentence. This theory is called the Big Bang theory. Around ...
... The Big Bang Theory Cosmologists—people who study the components, evolution, and physics of the entire Universe—now believe that all matter and energy in the Universe expanded from a point that was smaller than the period at the end of this sentence. This theory is called the Big Bang theory. Around ...
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.