10) Physics and Chemistry of the Diffuse Interstellar Medium
... Non-thermal rotational populations in the outer layers (optical pumping), Increasing self-shielding with cloud depth. HD ...
... Non-thermal rotational populations in the outer layers (optical pumping), Increasing self-shielding with cloud depth. HD ...
Review: How does a star`s mass determine its life story?
... According to the conservation of angular momentum, what would happen if a star orbiting in a direction opposite the neutron’s star rotation fell onto a neutron star? A. The neutron star’s rotation would speed up. B. The neutron star’s rotation would slow down. C. Nothing. The directions would cancel ...
... According to the conservation of angular momentum, what would happen if a star orbiting in a direction opposite the neutron’s star rotation fell onto a neutron star? A. The neutron star’s rotation would speed up. B. The neutron star’s rotation would slow down. C. Nothing. The directions would cancel ...
THREE Li-RICH K GIANTS - Indian Institute of Astrophysics
... near-solar metallicity spans a small range: log ( Li) 3:3 for ½Fe/ H 0:0 to log (Li) 3:1 for ½ Fe/H 0:3 (Lambert & Reddy 2004). This lithium abundance is identified with that of the interstellar gas from which the stars formed. Lithium is predicted to be destroyed throughout a main-se ...
... near-solar metallicity spans a small range: log ( Li) 3:3 for ½Fe/ H 0:0 to log (Li) 3:1 for ½ Fe/H 0:3 (Lambert & Reddy 2004). This lithium abundance is identified with that of the interstellar gas from which the stars formed. Lithium is predicted to be destroyed throughout a main-se ...
Mass-radius Relations for Helium White Dwarfs
... In recent years, white dwarf stars are receiving increasing attention. The theoretical relationship between the mass and radius of a white dwarf is important in interpreting some of the observational results. M-R relation was first defined by Chandrasekhar [4]. Later Hamada and Salpeter [5] obtained ...
... In recent years, white dwarf stars are receiving increasing attention. The theoretical relationship between the mass and radius of a white dwarf is important in interpreting some of the observational results. M-R relation was first defined by Chandrasekhar [4]. Later Hamada and Salpeter [5] obtained ...
Galactic Evolution of Silicon Isotopes: Applications to
... vast majority of the chemical elements, including the silicon ...
... vast majority of the chemical elements, including the silicon ...
A third red supergiant rich cluster in the Scutum
... Therefore, given their magnitudes and red colours, we identify S23–27 as potential objects of interest, but as with our second group, they require spectroscopic follow up to ascertain their nature and relationship to RSGC3 (Table 1). To summarise, based solely on their near-IR properties we identify ...
... Therefore, given their magnitudes and red colours, we identify S23–27 as potential objects of interest, but as with our second group, they require spectroscopic follow up to ascertain their nature and relationship to RSGC3 (Table 1). To summarise, based solely on their near-IR properties we identify ...
The Evolutionary Status of Be Stars in Clusters and in the Galactic
... by a scenario of evolutionary enhancement of the rotational velocity over the main sequence lifetime. The likelihood of such hypothesis is supported by recent theoretical and observational results. ¿From theoretical evolutionary models taking into account the stellar rotation, Meynet & Maeder (2000) ...
... by a scenario of evolutionary enhancement of the rotational velocity over the main sequence lifetime. The likelihood of such hypothesis is supported by recent theoretical and observational results. ¿From theoretical evolutionary models taking into account the stellar rotation, Meynet & Maeder (2000) ...
When Will Mankind Achieve “First Contact” with Extraterrestrial Life
... advanced intelligent life forms that exist in our solar system, we must look beyond our own “backyard” to even have a chance at finding other life forms that have had enough time, as well as luck (in terms of avoiding destruction) to be able to slowly evolve into creatures more similar to us. Fortun ...
... advanced intelligent life forms that exist in our solar system, we must look beyond our own “backyard” to even have a chance at finding other life forms that have had enough time, as well as luck (in terms of avoiding destruction) to be able to slowly evolve into creatures more similar to us. Fortun ...
Modeling the chemical evolution of the Galaxy halo
... system can be obtained from the kinematics and chemical composition of its stars. In particular, low-mass stars (m < 1 M ) live for a time comparable to or much longer than the present age of the Universe, retaining in their atmospheres a record of the chemical composition of the gas out of which t ...
... system can be obtained from the kinematics and chemical composition of its stars. In particular, low-mass stars (m < 1 M ) live for a time comparable to or much longer than the present age of the Universe, retaining in their atmospheres a record of the chemical composition of the gas out of which t ...
Spectroscopic Binaries - Thüringer Landessternwarte Tautenburg
... (valid for weak lines) - self-similar local profile shape - linear addition of blends Determination of P = linear deconvolution problem search for the least squares solution Improvements: - recover the individual line strengths - use line lists for multi-component atmospheres ...
... (valid for weak lines) - self-similar local profile shape - linear addition of blends Determination of P = linear deconvolution problem search for the least squares solution Improvements: - recover the individual line strengths - use line lists for multi-component atmospheres ...
Studying explosive phenomena in astrophysics by the example of
... to trace the entire life cycle of any concrete star. But huge number of observed stars gives us an opportunity to observe them at different stages of their existence - from initial formation by condensation of molecular clouds and up to their death, which for some stars is marked by the brightest fl ...
... to trace the entire life cycle of any concrete star. But huge number of observed stars gives us an opportunity to observe them at different stages of their existence - from initial formation by condensation of molecular clouds and up to their death, which for some stars is marked by the brightest fl ...
SouthamptonTalkPitkin - LIGO dcc
... • precision tests of correctness of GR in strong field regime • are black holes as GR predicts (“no-hair” theorem)? – Behavior of matter at nuclear densities and pressures • what is the composition of neutron star? Neutron star EOS: Credit: Demorest et al, Nature 467, 1081-1083 (2010) ...
... • precision tests of correctness of GR in strong field regime • are black holes as GR predicts (“no-hair” theorem)? – Behavior of matter at nuclear densities and pressures • what is the composition of neutron star? Neutron star EOS: Credit: Demorest et al, Nature 467, 1081-1083 (2010) ...
PDF Format
... Although there was some suspicion that W UMa stars were not contact systems (Wood 1969), the contact binary model is the generally accepted view. The pair are two main sequence stars of different masses in physical contact, with mass ratios higher than ten-to-one in some cases (Genet et al. 2005). T ...
... Although there was some suspicion that W UMa stars were not contact systems (Wood 1969), the contact binary model is the generally accepted view. The pair are two main sequence stars of different masses in physical contact, with mass ratios higher than ten-to-one in some cases (Genet et al. 2005). T ...
astronomical oxygen isotopic evidence for supernova
... instance signifies this logarithmic form of the delta notation). 2. GALACTIC CHEMICAL EVOLUTION OF 18 O/17 O Both 17 O and 18 O are secondary nuclides, produced by H and He burning, respectively (Meyer et al. 2008). One expects their solar ratio to be that of the bulk of the Galaxy at the time of so ...
... instance signifies this logarithmic form of the delta notation). 2. GALACTIC CHEMICAL EVOLUTION OF 18 O/17 O Both 17 O and 18 O are secondary nuclides, produced by H and He burning, respectively (Meyer et al. 2008). One expects their solar ratio to be that of the bulk of the Galaxy at the time of so ...
A new isolated dSph galaxy near the Local Group
... age and single metallicity populations). We used the Padova2000 theoretical isochrones (Girardi et al. 2000) and a Salpeter (1955) initial mass function (IMF). The synthetic diagrams were altered by the same incompleteness, crowding effects and photometric systematics as those determined for the obs ...
... age and single metallicity populations). We used the Padova2000 theoretical isochrones (Girardi et al. 2000) and a Salpeter (1955) initial mass function (IMF). The synthetic diagrams were altered by the same incompleteness, crowding effects and photometric systematics as those determined for the obs ...
Working with Magnitudes and Color Indices 1 A quick review of
... on the mass of the star, as does the color index. Thus the high mass stars, which tend to pull the B −V index negative because of their high Planck temperatures, also are the first to run out of Hydrogen in their core. They are the first ones to evolve off of the main sequence (remember that the time a ...
... on the mass of the star, as does the color index. Thus the high mass stars, which tend to pull the B −V index negative because of their high Planck temperatures, also are the first to run out of Hydrogen in their core. They are the first ones to evolve off of the main sequence (remember that the time a ...
radial metallicity gradients and age-metallicity relation of stars in the
... solar neighbourhood. The survey selection box was defined using the 2MASS photometry: 12 < J < 14 and 0.23 < J − K < 0.45 +0.5E(B−V); if there were not enough targets, the red edge was extended2. With these criteria, we are predominantly selecting FG stars with magnitudes down to V = 16.5 (Gilmore e ...
... solar neighbourhood. The survey selection box was defined using the 2MASS photometry: 12 < J < 14 and 0.23 < J − K < 0.45 +0.5E(B−V); if there were not enough targets, the red edge was extended2. With these criteria, we are predominantly selecting FG stars with magnitudes down to V = 16.5 (Gilmore e ...
Two extremely luminous WN stars in the Galactic center with
... and contains many OB-type stars, the more evolved Quintuplet cluster (3–5 Myr old) harbors many Wolf-Rayet (WR) stars. Besides these compact stellar conglomerates, many high-mass stars whose association with stellar clusters is not obvious are scattered in the GC. Among these are the rather isolated ...
... and contains many OB-type stars, the more evolved Quintuplet cluster (3–5 Myr old) harbors many Wolf-Rayet (WR) stars. Besides these compact stellar conglomerates, many high-mass stars whose association with stellar clusters is not obvious are scattered in the GC. Among these are the rather isolated ...
Magnetars origin and progenitors with enhanced rotation'
... Magnetars origin and progenitors with enhanced rotation S.B. Popov, M.E. Prokhorov (Sternberg Astronomical Institute) ...
... Magnetars origin and progenitors with enhanced rotation S.B. Popov, M.E. Prokhorov (Sternberg Astronomical Institute) ...
17.1 Introduction
... edge-on inclination) rotation velocity. In a general sense, the TF relation can be understood in terms of the virial relation applied to rotationally supported disk galaxies, under the assumption of a constant mass-to-light ratio. However, a detailed self-consistent physical picture that includes th ...
... edge-on inclination) rotation velocity. In a general sense, the TF relation can be understood in terms of the virial relation applied to rotationally supported disk galaxies, under the assumption of a constant mass-to-light ratio. However, a detailed self-consistent physical picture that includes th ...
nuclear
... persistent X-ray flux • The accretion rate cannot (much) exceed the Eddington limit, at which point the radiation pressure balances gravitational attraction, preventing further accretion • Many LMXBs are transients, that is they undergo outbursts of ~weeks separated by months-years • During these ou ...
... persistent X-ray flux • The accretion rate cannot (much) exceed the Eddington limit, at which point the radiation pressure balances gravitational attraction, preventing further accretion • Many LMXBs are transients, that is they undergo outbursts of ~weeks separated by months-years • During these ou ...
Chemical composition of B-type supergiants in the OB8, OB10
... Radial velocities of the OB48 stars and the OB78 stars, OB78-277 & OB78-478, agree within 10% of the radial velocities determined by Rubin & Ford (1970) for H II regions in the relevant OB associations. OB78-159 has a radial velocity significantly less than that expected from a star situated in the ...
... Radial velocities of the OB48 stars and the OB78 stars, OB78-277 & OB78-478, agree within 10% of the radial velocities determined by Rubin & Ford (1970) for H II regions in the relevant OB associations. OB78-159 has a radial velocity significantly less than that expected from a star situated in the ...
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.