Neutron stars: compact objects with relativistic
... [e.g. Ref. 26]. This value is 14 orders of magnitude larger than its solar counterpart. These two estimates on compactness and curvature assert that relativistic gravity is indispensable for the description of neutron stars. One may thus hope to employ neutron stars for seeking deviations from gener ...
... [e.g. Ref. 26]. This value is 14 orders of magnitude larger than its solar counterpart. These two estimates on compactness and curvature assert that relativistic gravity is indispensable for the description of neutron stars. One may thus hope to employ neutron stars for seeking deviations from gener ...
L25 A NEW CULPRIT IN THE SECOND
... reveal that the red horizontal branch (RHB) stars are strongly concentrated toward the center of the galaxy relative to the dominant old population in Sculptor, confirming an earlier claim of such a gradient. Since we find no radial gradients of the age or metallicity distribution within Sculptor, n ...
... reveal that the red horizontal branch (RHB) stars are strongly concentrated toward the center of the galaxy relative to the dominant old population in Sculptor, confirming an earlier claim of such a gradient. Since we find no radial gradients of the age or metallicity distribution within Sculptor, n ...
Visible neutral helium lines in main sequence B-type stars
... in the 410-710 nm interval for a sample of B-type main sequence stars. Such measurements have been compared with new calculations which combine ATLAS9 LTE model atmospheres, and NLTE radiative transfer for the line formation with updated atomic parameters. We have investigated the effects of line bl ...
... in the 410-710 nm interval for a sample of B-type main sequence stars. Such measurements have been compared with new calculations which combine ATLAS9 LTE model atmospheres, and NLTE radiative transfer for the line formation with updated atomic parameters. We have investigated the effects of line bl ...
Super and massive AGB stars-IV. Final fates
... 1 M⊙ noting this value is highly dependent on stellar model parameters, and in particular on the accurate determination of the core mass at the cessation of central helium burning. The white dwarf/gravitational collapse supernova boundary is also important from a galactic chemical evolution perspect ...
... 1 M⊙ noting this value is highly dependent on stellar model parameters, and in particular on the accurate determination of the core mass at the cessation of central helium burning. The white dwarf/gravitational collapse supernova boundary is also important from a galactic chemical evolution perspect ...
PowerPoint
... • Study tips. We have covered a lot of material in a short time, so here are some tips on how to approach your studies for the exam. – Topics covered in lectures should be stressed. – Homework questions have good examples of questions that may show up on the exam. An excellent way to begin studying ...
... • Study tips. We have covered a lot of material in a short time, so here are some tips on how to approach your studies for the exam. – Topics covered in lectures should be stressed. – Homework questions have good examples of questions that may show up on the exam. An excellent way to begin studying ...
Oscillation Modes of Strange Quark Stars with a Strangelet Crust
... “constant” is really an effective parameter of the model, and not an actual physical quantity. We therefore keep the value of quark mass fixed at 100 MeV and hold the central density constant, but vary the value of the Bag constant and µcrit self-consistently from the equation of state to generate d ...
... “constant” is really an effective parameter of the model, and not an actual physical quantity. We therefore keep the value of quark mass fixed at 100 MeV and hold the central density constant, but vary the value of the Bag constant and µcrit self-consistently from the equation of state to generate d ...
Stars in the Sky Stars in the Sky
... that light travels through space in 1 year. Because the speed of light through space is about 300,000 km/s, it travels approximately 9.46 trillion kilometers in 1 year! Figure 6 below illustrates how far away some stars that we see really are. Even after astronomers figured out that stars were far a ...
... that light travels through space in 1 year. Because the speed of light through space is about 300,000 km/s, it travels approximately 9.46 trillion kilometers in 1 year! Figure 6 below illustrates how far away some stars that we see really are. Even after astronomers figured out that stars were far a ...
Survey of Astrophysics A110 Cosmology
... we are looking further and further into the past this implies that the Universe is not constant --- it evolves with time. • Attempts (sometimes very elaborate) to modify the Steady State Theory to account for the observed evolution do not provide a convincing explanation of the Universe. The Big Ban ...
... we are looking further and further into the past this implies that the Universe is not constant --- it evolves with time. • Attempts (sometimes very elaborate) to modify the Steady State Theory to account for the observed evolution do not provide a convincing explanation of the Universe. The Big Ban ...
Pulsating Stars: Stars that Breathe
... In 1914, the American astronomer, Harlow Shapley, suggested that the observed variations in temperature and brightness of Cepheid variables were caused by radial pulsation. He argued that binary theories of stellar pulsation should be discarded and that astronomers should seek a mechanism by which s ...
... In 1914, the American astronomer, Harlow Shapley, suggested that the observed variations in temperature and brightness of Cepheid variables were caused by radial pulsation. He argued that binary theories of stellar pulsation should be discarded and that astronomers should seek a mechanism by which s ...
the reality of the wolf 630 moving group - TigerPrints
... and chemical evolution of the Galactic disk. To this end, one of the principle approaches for probing the disk has been to study the so-called galactic (or open) clusters, broadly defined as gravitionally bound groups of hundreds to thousands of stars in the galactic disk. Clusters are valuable astr ...
... and chemical evolution of the Galactic disk. To this end, one of the principle approaches for probing the disk has been to study the so-called galactic (or open) clusters, broadly defined as gravitionally bound groups of hundreds to thousands of stars in the galactic disk. Clusters are valuable astr ...
Follow-up observations of extremely metal
... Context. The most metal-poor stars in the Milky Way witnessed the early phases of formation of the Galaxy, and have chemical ...
... Context. The most metal-poor stars in the Milky Way witnessed the early phases of formation of the Galaxy, and have chemical ...
Evolution, Mass Loss and Variability of Low and Intermediate
... Mass Loss from Low and Intermediate Mass Stars Significant mass loss occurs in two phases 1. In red giants before large amplitude (Mira) pulsation starts. These mass loss rates are slow (<10-8 Msun/year). This is the dominant form of mass loss in the lowest mass evolved stars – globular cluster sta ...
... Mass Loss from Low and Intermediate Mass Stars Significant mass loss occurs in two phases 1. In red giants before large amplitude (Mira) pulsation starts. These mass loss rates are slow (<10-8 Msun/year). This is the dominant form of mass loss in the lowest mass evolved stars – globular cluster sta ...
Observations and three-dimensional photoionization modelling of
... in Table 5, together with the ionization potential required to create the emitting ions. We obtained Te and Ne from temperaturesensitive and density-sensitive emission lines by solving the equilibrium equations of level populations for a multilevel atomic model using EQUIB code (Howarth & Adams 1981 ...
... in Table 5, together with the ionization potential required to create the emitting ions. We obtained Te and Ne from temperaturesensitive and density-sensitive emission lines by solving the equilibrium equations of level populations for a multilevel atomic model using EQUIB code (Howarth & Adams 1981 ...
Astrophysics in a Nutshell, Second Edition
... Figure 4.1 Illustration of post-main-sequence evolution on the H-R diagram. Top: Observed H-R diagram for stars in the globular cluster M3 (more on star clusters in chapter 5.1.4). The main-sequence turnoff marks the point at which stars are now leaving the main sequence and evolving onto the red-gi ...
... Figure 4.1 Illustration of post-main-sequence evolution on the H-R diagram. Top: Observed H-R diagram for stars in the globular cluster M3 (more on star clusters in chapter 5.1.4). The main-sequence turnoff marks the point at which stars are now leaving the main sequence and evolving onto the red-gi ...
- Mineralogical Society of America
... in the early Solar System, such as heating and collision, and were eventually incorporated into the parent bodies of primitive meteorites. Presolar grains are identified by their having isotopic compositions that can be drastically different from terrestrial, and from one another, depending on their ...
... in the early Solar System, such as heating and collision, and were eventually incorporated into the parent bodies of primitive meteorites. Presolar grains are identified by their having isotopic compositions that can be drastically different from terrestrial, and from one another, depending on their ...
Nucleus Chapter 1
... a billion atoms in a typical virus and a single glass of water contains more atoms than there are glasses of water in all the seas and oceans on Earth. This book is about entities much smaller even than atoms. Each atom has a nucleus at its centre that is typically about ten thousand times smaller s ...
... a billion atoms in a typical virus and a single glass of water contains more atoms than there are glasses of water in all the seas and oceans on Earth. This book is about entities much smaller even than atoms. Each atom has a nucleus at its centre that is typically about ten thousand times smaller s ...
Chemical Evolution of Galactic Systems
... models, in order to gain insight into the protogalaxy’s age and star formation history. We continue investigating the high-redshift universe, turning our attention to the issue of space-time variations in the fine-structure constant, as suggested by quasar absorption-line constraints. An excess abun ...
... models, in order to gain insight into the protogalaxy’s age and star formation history. We continue investigating the high-redshift universe, turning our attention to the issue of space-time variations in the fine-structure constant, as suggested by quasar absorption-line constraints. An excess abun ...
FORMATION OF LATE-TYPE SPIRAL GALAXIES: GAS RETURN
... (Governato et al. 2009b), the standard models apparently fail to form high-spin, disk-dominated galaxies. A stellar evolution process that is more general than supernovae feedback is the continuous return of gas from stars of any mass, in particular through stellar winds and planetary nebulae (Faber ...
... (Governato et al. 2009b), the standard models apparently fail to form high-spin, disk-dominated galaxies. A stellar evolution process that is more general than supernovae feedback is the continuous return of gas from stars of any mass, in particular through stellar winds and planetary nebulae (Faber ...
radioactive 26a1 in the galaxy: observations versus theory
... of cases observations reveal only elemental abundances, through electromagnetic transitions in the atomic shells. However, it is individual isotopes, not elements, that participate in nuclear reactions. This is not necessarily a big problem, since many elements have only one dominant isotope. Still, ...
... of cases observations reveal only elemental abundances, through electromagnetic transitions in the atomic shells. However, it is individual isotopes, not elements, that participate in nuclear reactions. This is not necessarily a big problem, since many elements have only one dominant isotope. Still, ...
Astronomy Astrophysics Massive open star clusters using the VVV survey &
... the cluster area revealed that two objects are part of the disk population (two early-B dwarfs), and two stars form part of the cluster main-sequence population. From their spectral classification and the cluster CMD we were able to deduce that earlier stars than these two observed OB-stars are prob ...
... the cluster area revealed that two objects are part of the disk population (two early-B dwarfs), and two stars form part of the cluster main-sequence population. From their spectral classification and the cluster CMD we were able to deduce that earlier stars than these two observed OB-stars are prob ...
The star-forming environment of an ultraluminous X-ray
... a young BH originating in the recent episode of massive star formation; however, they also rule out an association with young massive star clusters (none are present in the X7 field). We speculate that other mechanisms may lead to the formation of relatively massive BHs (perhaps M ∼ 50–100 M ) from ...
... a young BH originating in the recent episode of massive star formation; however, they also rule out an association with young massive star clusters (none are present in the X7 field). We speculate that other mechanisms may lead to the formation of relatively massive BHs (perhaps M ∼ 50–100 M ) from ...
The Mass-loss Rate of Red Supergiant
... the end stages of massive stars. The final stages of massive star evolution can enrich our knowledge about a multitude of astrophysical processes. 1. which stars produce neutron stars and black holes 2. how galaxies are seeded with heavy elements ...
... the end stages of massive stars. The final stages of massive star evolution can enrich our knowledge about a multitude of astrophysical processes. 1. which stars produce neutron stars and black holes 2. how galaxies are seeded with heavy elements ...
looking for progenitors of cool Ap stars
... ages in our sample did not present any evidence supporting the hypothesis that Ap stars suffer considerable magnetic braking during their MS life. According to these results, there must exist progenitors of Ap stars in the form of normal A stars, which probably rotate slowly unless some unknown mech ...
... ages in our sample did not present any evidence supporting the hypothesis that Ap stars suffer considerable magnetic braking during their MS life. According to these results, there must exist progenitors of Ap stars in the form of normal A stars, which probably rotate slowly unless some unknown mech ...
www.astro.utu.fi
... 2000 very nearby halo stars as model constraints. Our model is physical, the Sirko 'model' phenomological. ...
... 2000 very nearby halo stars as model constraints. Our model is physical, the Sirko 'model' phenomological. ...
Collisions and close encounters involving massive main
... In this work, we study a smaller parameter space than that covered by Freitag & Benz (2005), but our SPH calculations are at higher resolution (typically involving ∼7 × 104 particles) and include the highest-resolution simulations of massive stellar encounters ever performed, using ∼6 × 105 particle ...
... In this work, we study a smaller parameter space than that covered by Freitag & Benz (2005), but our SPH calculations are at higher resolution (typically involving ∼7 × 104 particles) and include the highest-resolution simulations of massive stellar encounters ever performed, using ∼6 × 105 particle ...
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.