Self-similarity in the chemical evolution of galaxies and the delay
... Since the genesis of this paper, more samples have appeared that extended the very local samples used here using CoRoT and Kepler data with spectroscopic follow-up (Chiappini et al. 2015; Anders et al. 2016; Martig et al. 2015). Adding these stars would not change the conclusions of this paper in an ...
... Since the genesis of this paper, more samples have appeared that extended the very local samples used here using CoRoT and Kepler data with spectroscopic follow-up (Chiappini et al. 2015; Anders et al. 2016; Martig et al. 2015). Adding these stars would not change the conclusions of this paper in an ...
Observations of Interstellar Carbon Compounds
... also x(H) / x(C sp3 ) ∼ 2.33. Taking into account that only the infrared moderately active modes are observed, this sets a lower limit to the hydrogen content of the material observed, meaning a fractional hydrogen content in the a-C:H of x(H)≥0.2. These constraints can be brought together in a tern ...
... also x(H) / x(C sp3 ) ∼ 2.33. Taking into account that only the infrared moderately active modes are observed, this sets a lower limit to the hydrogen content of the material observed, meaning a fractional hydrogen content in the a-C:H of x(H)≥0.2. These constraints can be brought together in a tern ...
Observations with Herschel: High-mass star formation and the
... is essential to our understanding of the cosmos. When the Earth’s opaque atmosphere prevents the far-infrared radiation to reach ground based antennas, space observatories become crucial to collect that important piece of the large puzzle that otherwise would have been lost. In this thesis, we use o ...
... is essential to our understanding of the cosmos. When the Earth’s opaque atmosphere prevents the far-infrared radiation to reach ground based antennas, space observatories become crucial to collect that important piece of the large puzzle that otherwise would have been lost. In this thesis, we use o ...
Galaxies
... are also nearly all the same color: somewhat redder than the Sun. On the tuning fork diagram, they are classified as E, followed by a number indicating how elliptical a given galaxy is. The higher the number, the more elliptical the galaxy; that is, the longer the galaxy is with respect to its width ...
... are also nearly all the same color: somewhat redder than the Sun. On the tuning fork diagram, they are classified as E, followed by a number indicating how elliptical a given galaxy is. The higher the number, the more elliptical the galaxy; that is, the longer the galaxy is with respect to its width ...
BD−21 3873: another yellow-symbiotic barium star
... A discussion of the f -values employed in the calculations and of the corresponding uncertainties has been presented in Paper I and will not be repeated here. Since the H − K and J − K colors of BD−21◦ 3873 and AG Dra are almost identical (J − K = 0.91 and 0.94, H − K = 0.16 and 0.18 for AG Dra and ...
... A discussion of the f -values employed in the calculations and of the corresponding uncertainties has been presented in Paper I and will not be repeated here. Since the H − K and J − K colors of BD−21◦ 3873 and AG Dra are almost identical (J − K = 0.91 and 0.94, H − K = 0.16 and 0.18 for AG Dra and ...
Option D Lesson 6 Cosmology and Further - Physics
... evidence for the Big Bang? • The cosmic background radiation (sometimes called the CBR), is the afterglow of the big bang, cooled to a faint whisper in the microwave spectrum by the expansion of the Universe for 15 billion years (which causes the radiation originally produced in the big bang to reds ...
... evidence for the Big Bang? • The cosmic background radiation (sometimes called the CBR), is the afterglow of the big bang, cooled to a faint whisper in the microwave spectrum by the expansion of the Universe for 15 billion years (which causes the radiation originally produced in the big bang to reds ...
Chapter 4 On the possibility of a helium white dwarf donor in the
... layers that were lost being outside the Roche lobe. Juett et al. and Nelemans et al. suggest that spallation of accreted elements may be important (e.g., Bildsten, Salpeter & Wasserman 1992). However, it is not trivial to invoke spallation. Spallation requires hydrogen nuclei (protons) to bombard th ...
... layers that were lost being outside the Roche lobe. Juett et al. and Nelemans et al. suggest that spallation of accreted elements may be important (e.g., Bildsten, Salpeter & Wasserman 1992). However, it is not trivial to invoke spallation. Spallation requires hydrogen nuclei (protons) to bombard th ...
Dr. David Toback Lecture 19
... Problem: We don’t know if we have discovered all the fundamental particles yet! ...
... Problem: We don’t know if we have discovered all the fundamental particles yet! ...
The Age and Stellar Parameters of the Procyon Binary System
... from measurements of the angular diameter with the ESO Very Large Telescope Interferometer. The radius is R = 2.031±0.013R⊙ or ±0.65% (Aufdenberg, Ludwig, & Kervella 2005). This radius value is based on the authors “best estimate” angular diameter of 5.404±0.031 mas at 2.2µ. Note that the authors co ...
... from measurements of the angular diameter with the ESO Very Large Telescope Interferometer. The radius is R = 2.031±0.013R⊙ or ±0.65% (Aufdenberg, Ludwig, & Kervella 2005). This radius value is based on the authors “best estimate” angular diameter of 5.404±0.031 mas at 2.2µ. Note that the authors co ...
The Spirit in Biodynamic Agriculture
... source from where all other things arise, has to be considered as central to manifestation as the much talked of Etheric and Astral. In several ways it is unfortunate we use the term Spirit, as it has so many connotations for so many people. Many folks give it some religious reference, pertaining to ...
... source from where all other things arise, has to be considered as central to manifestation as the much talked of Etheric and Astral. In several ways it is unfortunate we use the term Spirit, as it has so many connotations for so many people. Many folks give it some religious reference, pertaining to ...
chemical compositions of rv tauri stars and related objects
... single stars; in fact, RVa objects are known to have binary companions, e.g., AC Her (see van Winckel et al. 1998) and RU Cen (see Maas, van Winckel, & Waelkens 2002). From a comprehensive study of RV Tauri binaries, van Winckel et al. (1999); Maas et al. (2002) proposed that the RV Tauri photometri ...
... single stars; in fact, RVa objects are known to have binary companions, e.g., AC Her (see van Winckel et al. 1998) and RU Cen (see Maas, van Winckel, & Waelkens 2002). From a comprehensive study of RV Tauri binaries, van Winckel et al. (1999); Maas et al. (2002) proposed that the RV Tauri photometri ...
Dark matter
... controversial whether or not these nebulae were "island universes" outside our Milky Way.[3] Ten years later, Alexander Friedmann, a Russian cosmologist and mathematician, derived the Friedmann equations from Albert Einstein's equations of general relativity, showing that the universe might be expan ...
... controversial whether or not these nebulae were "island universes" outside our Milky Way.[3] Ten years later, Alexander Friedmann, a Russian cosmologist and mathematician, derived the Friedmann equations from Albert Einstein's equations of general relativity, showing that the universe might be expan ...
Galactic Evolution of Silicon Isotopes: Application to Presolar SiC
... Type II supernovae are the principle origin site of the vast majority of the chemical elements, including the silicon isotopes. Typically, the matter ejected contains about 10 times as many atoms of a given heavy element than did the initial matter of the massive star. Type Ia supernovae can a ect t ...
... Type II supernovae are the principle origin site of the vast majority of the chemical elements, including the silicon isotopes. Typically, the matter ejected contains about 10 times as many atoms of a given heavy element than did the initial matter of the massive star. Type Ia supernovae can a ect t ...
Chemical evolution models for the dwarf spheroidal galaxies Leo 1
... mainly by the star formation rate (SFR) and galactic wind efficiency prescriptions, chosen to reproduce the main observational constraints. In our model, when the thermal energy of the interstellar medium (ISM) is equal or higher than the binding energy of the galaxy, a galactic wind occurs, thus remo ...
... mainly by the star formation rate (SFR) and galactic wind efficiency prescriptions, chosen to reproduce the main observational constraints. In our model, when the thermal energy of the interstellar medium (ISM) is equal or higher than the binding energy of the galaxy, a galactic wind occurs, thus remo ...
L103 A NEW MILKY WAY DWARF SATELLITE IN CANES
... of the Milky Way. Together with the two dwarf irregulars (the Large and Small Magellanic Clouds), these make up all the known satellite galaxies of the Milky Way. The dSphs have such low surface brightness that they have often been found serendipitously. For example, while Sextans (Irwin et al. 1990 ...
... of the Milky Way. Together with the two dwarf irregulars (the Large and Small Magellanic Clouds), these make up all the known satellite galaxies of the Milky Way. The dSphs have such low surface brightness that they have often been found serendipitously. For example, while Sextans (Irwin et al. 1990 ...
Protogalaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org S G Djorgovski
... that about a half of the STELLAR MASS in galaxies today is in the old populations, bulges and stellar halos, and thus about a half of all star formation in the universe’s history can be associated with PGs (this is admittedly dependent on how one wishes to define PGs). The key to estimating this ene ...
... that about a half of the STELLAR MASS in galaxies today is in the old populations, bulges and stellar halos, and thus about a half of all star formation in the universe’s history can be associated with PGs (this is admittedly dependent on how one wishes to define PGs). The key to estimating this ene ...
Testing
... Stars in the disk all orbit in the same direction with a little up-and-down motion. © 2010 Pearson Education, Inc. ...
... Stars in the disk all orbit in the same direction with a little up-and-down motion. © 2010 Pearson Education, Inc. ...
Protogalaxies
... that about a half of the STELLAR MASS in galaxies today is in the old populations, bulges and stellar halos, and thus about a half of all star formation in the universe’s history can be associated with PGs (this is admittedly dependent on how one wishes to define PGs). The key to estimating this ene ...
... that about a half of the STELLAR MASS in galaxies today is in the old populations, bulges and stellar halos, and thus about a half of all star formation in the universe’s history can be associated with PGs (this is admittedly dependent on how one wishes to define PGs). The key to estimating this ene ...
Word - The Open University
... reduced. This has important implications for the ways in which the four fundamental interactions manifest themselves at different epochs. The four fundamental interactions, that is electromagnetic interaction, weak interaction, strong interaction and gravitational interaction, have very different st ...
... reduced. This has important implications for the ways in which the four fundamental interactions manifest themselves at different epochs. The four fundamental interactions, that is electromagnetic interaction, weak interaction, strong interaction and gravitational interaction, have very different st ...
The Alpha Centauri binary system
... λλ 5100, 5245, 5342, 5411, 5528, 5691, 5825, 6128 and 6242 Å, with spectral coverage of 90 Å each. The chemical species represented by spectral lines reasonably free from blending are Na I, Si I, Ca I, Sc I, Sc II, Ti I, Ti II,V I, Cr I, Cr II, Mn I, Fe I, Fe II, Co I, Ni I, Cu I, Y II, Ba II. Add ...
... λλ 5100, 5245, 5342, 5411, 5528, 5691, 5825, 6128 and 6242 Å, with spectral coverage of 90 Å each. The chemical species represented by spectral lines reasonably free from blending are Na I, Si I, Ca I, Sc I, Sc II, Ti I, Ti II,V I, Cr I, Cr II, Mn I, Fe I, Fe II, Co I, Ni I, Cu I, Y II, Ba II. Add ...
Massive close binaries, observational characteristics - UvA-DARE
... close binary system with a not too small initial mass ratio (q = M2/M1 >_0.4) is, theoretically, expected to pass (see for example Van den Heuvel 1974, 1978, 1983 and 1993 and references therein). For such systems the first phase of mass transfer proceeds more or less "conservatively", i.e.: total m ...
... close binary system with a not too small initial mass ratio (q = M2/M1 >_0.4) is, theoretically, expected to pass (see for example Van den Heuvel 1974, 1978, 1983 and 1993 and references therein). For such systems the first phase of mass transfer proceeds more or less "conservatively", i.e.: total m ...
Star Formation in the Milky Way - HubbleSOURCE
... initial cloud at T=0 evolving over ~250,000 years to collapse and fragment form a small cluster of ~1200 stars. Some of the low mass members are formed in the inner cloud regions and ejected into outer regions of the ...
... initial cloud at T=0 evolving over ~250,000 years to collapse and fragment form a small cluster of ~1200 stars. Some of the low mass members are formed in the inner cloud regions and ejected into outer regions of the ...
DISCOVERY OF HOT SUPERGIANT STARS NEAR THE GALACTIC
... We report new results of a campaign to find Wolf-Rayet and O (WR/O) stars and high-mass X-ray binaries (HMXBs) in the Galactic center. We searched for candidates by cross-correlating the Two Micron All Sky Survey with a deep Chandra X-Ray Observatory catalog of point sources in the Radio Arches regi ...
... We report new results of a campaign to find Wolf-Rayet and O (WR/O) stars and high-mass X-ray binaries (HMXBs) in the Galactic center. We searched for candidates by cross-correlating the Two Micron All Sky Survey with a deep Chandra X-Ray Observatory catalog of point sources in the Radio Arches regi ...
Overview and historical perspective on Cosmology
... protons. D, He, 3He, Li. Depends on number of neutrinos. • 1 year, z = 106.5, photon number fixed, CMB can have BoseEinstein distribution with chemical potential if energy added ...
... protons. D, He, 3He, Li. Depends on number of neutrinos. • 1 year, z = 106.5, photon number fixed, CMB can have BoseEinstein distribution with chemical potential if energy added ...
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.