ASTRONOMY AND ASTROPHYSICS How many low
... Let us focus on the stars of the present sample that have passed the bump and do not behave as the majority. If we consider the objects with MV lower than -0.5, only 3 stars appear to be really “deviant” (see Table 2). V8 (NGC6656). As can be seen in Figs. 1 and 2, as soon as they are more luminous ...
... Let us focus on the stars of the present sample that have passed the bump and do not behave as the majority. If we consider the objects with MV lower than -0.5, only 3 stars appear to be really “deviant” (see Table 2). V8 (NGC6656). As can be seen in Figs. 1 and 2, as soon as they are more luminous ...
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... We can in principle image H I condensations in the still neutral, prereionization universe using the 21cm line. Several experiments are now being constructed or planned to do this, e.g., the Mileura WideField Array in Australia, or the Square Kilometer Array (SKA) ...
... We can in principle image H I condensations in the still neutral, prereionization universe using the 21cm line. Several experiments are now being constructed or planned to do this, e.g., the Mileura WideField Array in Australia, or the Square Kilometer Array (SKA) ...
FREE Sample Here - Find the cheapest test bank for your
... 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 ...
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... 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 ...
Lecture 22 - Center for Astrophysics and Space Astronomy CASA
... • Electrons and Positrons have cooled to point where they are no longer in equilibrium. T=1010K • Create photons. • One matter particle in hundred million is left. • Those are today’s electrons. ...
... • Electrons and Positrons have cooled to point where they are no longer in equilibrium. T=1010K • Create photons. • One matter particle in hundred million is left. • Those are today’s electrons. ...
New Discoveries in Planetary Systems and Star Formation through
... broad-band infrared (IR) observations; water has now been observed spectroscopically on an exoplanet (Grillmair et al. 2008). In the next decade observations will continue to drive the sophistication of planet atmosphere models (e.g. winds from close-in Jupiters; Murray-Clay et al. 2008). Gas giants ...
... broad-band infrared (IR) observations; water has now been observed spectroscopically on an exoplanet (Grillmair et al. 2008). In the next decade observations will continue to drive the sophistication of planet atmosphere models (e.g. winds from close-in Jupiters; Murray-Clay et al. 2008). Gas giants ...
Rocky planetesimals as the origin of metals in DZ stars
... in sufficient density a few to several times per Galactic orbit (on average) for the solar neighbourhood (Dupuis et al. 1992, 1993a; Dupuis, Fontaine & Wesemael 1993b). Several factors have continually challenged the ISM pollution scenario. First, the typical dearth of hydrogen relative to calcium i ...
... in sufficient density a few to several times per Galactic orbit (on average) for the solar neighbourhood (Dupuis et al. 1992, 1993a; Dupuis, Fontaine & Wesemael 1993b). Several factors have continually challenged the ISM pollution scenario. First, the typical dearth of hydrogen relative to calcium i ...
Diapositiva 1 - Dipartimento di Fisica
... ratio will always be 1.72≤q2/q1≤1.83. Ratio values lower than 1.72 show the presence of solar-like differential rotation with the equator rotating faster than the poles, while values higher than 1.83 may point at the presence of anti-solar differential rotation (the poles rotate faster than the equa ...
... ratio will always be 1.72≤q2/q1≤1.83. Ratio values lower than 1.72 show the presence of solar-like differential rotation with the equator rotating faster than the poles, while values higher than 1.83 may point at the presence of anti-solar differential rotation (the poles rotate faster than the equa ...
Dark Matter Capture in the first stars
... • Start with a few solar masses, guess the radius, see if DM luminosity matches luminosity of star (photosphere at roughly 6000K). If not adjust radius until it does. Smaller radius means larger gas density, pulls in more DM via adiabatic contraction, higher DM density and heating. Equilibrium condi ...
... • Start with a few solar masses, guess the radius, see if DM luminosity matches luminosity of star (photosphere at roughly 6000K). If not adjust radius until it does. Smaller radius means larger gas density, pulls in more DM via adiabatic contraction, higher DM density and heating. Equilibrium condi ...
Boron Abundances Across the" Li
... Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #HST-G0-12294. ...
... Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #HST-G0-12294. ...
astro-ph/0301519 PDF
... We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ~20000-110000K, based on far-UV spectroscopy with STIS/GHRS on HST, IUE and FUSE. Using our latest heavy element blanketed non-LTE stellar atmosphere calculations we have addressed the heavy ...
... We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ~20000-110000K, based on far-UV spectroscopy with STIS/GHRS on HST, IUE and FUSE. Using our latest heavy element blanketed non-LTE stellar atmosphere calculations we have addressed the heavy ...
Ch. 19 - Astro1010
... Often as a large star ages much of the fuel is used up and deposited as ‘ash’ in the iron core. The inward pressure on the iron core is enormous, due to the high mass of the star. As the core continues to become more and more dense, the protons react with one another to become neutrons + a flood of ...
... Often as a large star ages much of the fuel is used up and deposited as ‘ash’ in the iron core. The inward pressure on the iron core is enormous, due to the high mass of the star. As the core continues to become more and more dense, the protons react with one another to become neutrons + a flood of ...
pg. 271 - Cornell University
... on the lack of evidence of freshly synthesized carbon, concluded that the third dredge-up did not occur. For the first time, complete mid-infrared spectra (from 5.3 to 40 m) for this nebula are available. The infrared region of the spectrum is very useful for several reasons. The lines seen in the ...
... on the lack of evidence of freshly synthesized carbon, concluded that the third dredge-up did not occur. For the first time, complete mid-infrared spectra (from 5.3 to 40 m) for this nebula are available. The infrared region of the spectrum is very useful for several reasons. The lines seen in the ...
Stellar Evolution
... … another one, observed Energy equivalent to the entire mass by us with the MDM 1.3 m of the sun (E = mc2), converted into gamma-rays in just a few seconds! telescope on Kitt Peak! ...
... … another one, observed Energy equivalent to the entire mass by us with the MDM 1.3 m of the sun (E = mc2), converted into gamma-rays in just a few seconds! telescope on Kitt Peak! ...
exploring anticorrelations and light element variations
... up to 15 elements for nearly 100,000 stars, although fewer elements are generally detected in weak-lined metal-poor stars. APOGEE is in a unique position among the various Galactic spectroscopic surveys such as Gaia-ESO, (Gilmore et al. 2012), RAVE (Steinmetz et al. 2012), and GALAH (Freeman 2012), ...
... up to 15 elements for nearly 100,000 stars, although fewer elements are generally detected in weak-lined metal-poor stars. APOGEE is in a unique position among the various Galactic spectroscopic surveys such as Gaia-ESO, (Gilmore et al. 2012), RAVE (Steinmetz et al. 2012), and GALAH (Freeman 2012), ...
Stellar Winds and Hydrodynamic Atmospheres of Stars
... star with 8 Msun on main sequence ends up with 1 Msun 7 Msun re-cycled to ISM ejection of Planetary Nebula at tip of AGB ...
... star with 8 Msun on main sequence ends up with 1 Msun 7 Msun re-cycled to ISM ejection of Planetary Nebula at tip of AGB ...
Chemical Composition of Selected Metal Poor Stars
... of Big Bang nucleosynthesis, to understand the earliest episodes of star formation (or star formation history of our galaxy) and regarding the first heavy element producing objects. The study of their chemical composition, serve as a tool to constrain the model of stellar nucleosynthesis, yields of ...
... of Big Bang nucleosynthesis, to understand the earliest episodes of star formation (or star formation history of our galaxy) and regarding the first heavy element producing objects. The study of their chemical composition, serve as a tool to constrain the model of stellar nucleosynthesis, yields of ...
Interacting binary stars Properties of some binary stars are
... fades over a few weeks: Visual light curve of a classical nova event ...
... fades over a few weeks: Visual light curve of a classical nova event ...
G. Fiorentini a
... Gravitatio nal force between proton & electron ”This suggests that …large numbers are to be regarded not as constants, but as simple functions of our present epoch, expressed in atomic units. In this way we avoid the need of a theory to determine numbers of the order of 1039 “. ...
... Gravitatio nal force between proton & electron ”This suggests that …large numbers are to be regarded not as constants, but as simple functions of our present epoch, expressed in atomic units. In this way we avoid the need of a theory to determine numbers of the order of 1039 “. ...
Chapter 1 Introduction
... These equations bear further examination. The first and second terms on the left hand side of Equation 1.1 look like kinetic and gravitational potential energies, respectively, and the right hand side is effectively a total energy. Before continuing further, it is useful to define the “Hubble parame ...
... These equations bear further examination. The first and second terms on the left hand side of Equation 1.1 look like kinetic and gravitational potential energies, respectively, and the right hand side is effectively a total energy. Before continuing further, it is useful to define the “Hubble parame ...
Chapter 12 Pre-supernova evolution of massive stars
... We have seen that low- and intermediate-mass stars (with masses up to ≈ 8 M⊙ ) develop carbonoxygen cores that become degenerate after central He burning. As a consequence the maximum core temperature reached in these stars is smaller than the temperature required for carbon fusion. During the lates ...
... We have seen that low- and intermediate-mass stars (with masses up to ≈ 8 M⊙ ) develop carbonoxygen cores that become degenerate after central He burning. As a consequence the maximum core temperature reached in these stars is smaller than the temperature required for carbon fusion. During the lates ...
Chap 18 Cosmology v2
... cosmic light horizon. We cannot see any objects that may exist beyond the cosmic light horizon because light from these objects has not had enough time to reach us. ...
... cosmic light horizon. We cannot see any objects that may exist beyond the cosmic light horizon because light from these objects has not had enough time to reach us. ...
Astrophysics
... includes observations with space-based observatories, analytical and numerical modeling, and large-scale numerical simulations. In addition to work described below, topics include Big Bang nucleosynthesis, galactic chemical evolution, stellar winds, interacting binary stars, accretion disks, and pul ...
... includes observations with space-based observatories, analytical and numerical modeling, and large-scale numerical simulations. In addition to work described below, topics include Big Bang nucleosynthesis, galactic chemical evolution, stellar winds, interacting binary stars, accretion disks, and pul ...
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.