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On the trend of [Mg/Fe] among giant elliptical galaxies
... the more recent index calibrations and show that none of the current models for the chemical evolution of elliptical galaxies is able to reproduce exactly the observed slope of the < F e > versus M g2 relation, although the existing spread in the data makes this comparison quite difficult. In other ...
... the more recent index calibrations and show that none of the current models for the chemical evolution of elliptical galaxies is able to reproduce exactly the observed slope of the < F e > versus M g2 relation, although the existing spread in the data makes this comparison quite difficult. In other ...
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... obje t brighter than about 1/3 L , whi h orresponds to a period of about 5 minutes for a 1.4 M neutron star mass donor. Additionally, ultra ompa t binaries should stand out as being too hot for their magnitudes when plotted in a olor magnitude diagram. We note that ar hival HST data an be used ...
... obje t brighter than about 1/3 L , whi h orresponds to a period of about 5 minutes for a 1.4 M neutron star mass donor. Additionally, ultra ompa t binaries should stand out as being too hot for their magnitudes when plotted in a olor magnitude diagram. We note that ar hival HST data an be used ...
Neutron stars - Institut de Physique Nucleaire de Lyon
... L.D.Landau (1931) – anticipation [L.D.Landau, “On the theory of stars,” Physikalische Zs. Sowjetunion 1 (1932) 285]: for stars with M>1.5M☼ “density of matter becomes so great that atomic nuclei come in close contact, foming one gigantic nucleus’’. J.Chadwick – discovery of a neutron [Nature, Feb. ...
... L.D.Landau (1931) – anticipation [L.D.Landau, “On the theory of stars,” Physikalische Zs. Sowjetunion 1 (1932) 285]: for stars with M>1.5M☼ “density of matter becomes so great that atomic nuclei come in close contact, foming one gigantic nucleus’’. J.Chadwick – discovery of a neutron [Nature, Feb. ...
THE FINAL FATE OF STARS THAT IGNITE NEON AND OXYGEN
... the persistence of a propagating nuclear flame in the stellar interior (the radial stratification of the peak energy production and temperature). Figure 2 shows the energy production due to the key neon- and oxygen-burning reactions during the peak of the first neon shell flash episode in the 8.8 M ...
... the persistence of a propagating nuclear flame in the stellar interior (the radial stratification of the peak energy production and temperature). Figure 2 shows the energy production due to the key neon- and oxygen-burning reactions during the peak of the first neon shell flash episode in the 8.8 M ...
Neutron stars: compact objects with relativistic gravity
... solar system tests and binary pulsars, one may hope to provide even more stringent tests of general relativity by measuring mass and radius of neutron stars. This is hampered by the fact that the mass and radius of neutron stars are determined not only by the hydrostatic equilibrium equations of the ...
... solar system tests and binary pulsars, one may hope to provide even more stringent tests of general relativity by measuring mass and radius of neutron stars. This is hampered by the fact that the mass and radius of neutron stars are determined not only by the hydrostatic equilibrium equations of the ...
Winds of Main-Sequence Stars - Harvard
... • Wood et al. (2001, 2002, 2005) distinguished cool ISM H I Lyα absorption from hotter “piled up” H0 in stellar astrospheres. Derived M depends on models . . . ...
... • Wood et al. (2001, 2002, 2005) distinguished cool ISM H I Lyα absorption from hotter “piled up” H0 in stellar astrospheres. Derived M depends on models . . . ...
From PAHs to Solid Carbon
... produced using catalysts (Harris 2009). A single-wall CNT can be imagined as a graphene sheet rolled at a certain chiral angle. CNTs can grow up to lengths over 1 μm and with a range of diameters from 1 nm (for single walled) to around 50 nm for multi walled ones. The electronic properties vary from ...
... produced using catalysts (Harris 2009). A single-wall CNT can be imagined as a graphene sheet rolled at a certain chiral angle. CNTs can grow up to lengths over 1 μm and with a range of diameters from 1 nm (for single walled) to around 50 nm for multi walled ones. The electronic properties vary from ...
asteroseismological study of massive zz ceti stars with
... above ∼1.05 M , resulting from a progenitor star with masses between ∼7–8.5 M .6 High-mass white dwarf stars are not easy to find, not only because their intrinsically smaller number with respect to lower mass white dwarfs, but also because they evolve fast and have low luminosity due to their sma ...
... above ∼1.05 M , resulting from a progenitor star with masses between ∼7–8.5 M .6 High-mass white dwarf stars are not easy to find, not only because their intrinsically smaller number with respect to lower mass white dwarfs, but also because they evolve fast and have low luminosity due to their sma ...
RESEARCH STATEMENT Chromospheres and winds
... pulsations strong enough to deliver sufficient acoustic energy to the outer layers of cool stars are also not evident. Magnetic processes such as Alfvén waves are likely a major contributor to winds of dust–free, non–pulsating K and M giant and supergiant stars. However, current magnetic models do ...
... pulsations strong enough to deliver sufficient acoustic energy to the outer layers of cool stars are also not evident. Magnetic processes such as Alfvén waves are likely a major contributor to winds of dust–free, non–pulsating K and M giant and supergiant stars. However, current magnetic models do ...
Evolution of low mass stars
... resulted as the Universe cooled (this belief allowed him to predict the existence of the microwave background radiation, though). Sir Fred Hoyle (1915–2001), a British astronomer, disliked the big bang theory so much (he named the theory “big bang” in order to taunt over it) and argued that stars sh ...
... resulted as the Universe cooled (this belief allowed him to predict the existence of the microwave background radiation, though). Sir Fred Hoyle (1915–2001), a British astronomer, disliked the big bang theory so much (he named the theory “big bang” in order to taunt over it) and argued that stars sh ...
On the possibility of a helium white dwarf donor in the presumed
... outer 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 et al. 1992). However, it is not trivial to invoke spallation. Spallation requires hydrogen nuclei (protons) to bombard the higher- ...
... outer 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 et al. 1992). However, it is not trivial to invoke spallation. Spallation requires hydrogen nuclei (protons) to bombard the higher- ...
Here
... This work would not have been possible without the help and support of many people. I would like to take this opportunity to offer my thanks. First and foremost I would like to thank Chris for supervising me through the past three year. I have learnt much from him in this time, from the details of s ...
... This work would not have been possible without the help and support of many people. I would like to take this opportunity to offer my thanks. First and foremost I would like to thank Chris for supervising me through the past three year. I have learnt much from him in this time, from the details of s ...
Experimental f-Value and Isotopic Structure for the
... the forbidden line [O i] l6300 used for the determination of the oxygen abundance in cool stars. We also give wavelengths of the two isotopic line components of 58Ni and 60Ni derived from the asymmetric laboratory line profile. These two line components of Ni i have to be considered when calculating ...
... the forbidden line [O i] l6300 used for the determination of the oxygen abundance in cool stars. We also give wavelengths of the two isotopic line components of 58Ni and 60Ni derived from the asymmetric laboratory line profile. These two line components of Ni i have to be considered when calculating ...
The Universe - the Scientia Review
... Of the various types of galaxies, the spiral galaxy is by far the most common. In fact, About 77% of all known galaxies are spiral. There are a few main features that are found in all spiral galaxies, including a disc-like shape and a galactic bulge. The discs are usually This image of a spiral gala ...
... Of the various types of galaxies, the spiral galaxy is by far the most common. In fact, About 77% of all known galaxies are spiral. There are a few main features that are found in all spiral galaxies, including a disc-like shape and a galactic bulge. The discs are usually This image of a spiral gala ...
Priestly Contributions to Modern Science: The
... Lemaître’s principal area of study was relativistic cosmology. After completing his first doctorate in mathematics and studying relativity on his own as a seminarian, he had the tools to join Sir Arthur Eddington and Harlow Shapley in their investigation of the astronomical implications of relativi ...
... Lemaître’s principal area of study was relativistic cosmology. After completing his first doctorate in mathematics and studying relativity on his own as a seminarian, he had the tools to join Sir Arthur Eddington and Harlow Shapley in their investigation of the astronomical implications of relativi ...
A Test of Pre-Main-Sequence Lithium Depletion Models
... These studies clearly show that the presence of a strong Li I line at 6707.8Å is an indicator of youth in late-type stars. The regularity of lithium depletion in open clusters implies that the lithium line can act as a mass-dependent clock (Jeffries & Naylor 2001). By combining a measurement of the ...
... These studies clearly show that the presence of a strong Li I line at 6707.8Å is an indicator of youth in late-type stars. The regularity of lithium depletion in open clusters implies that the lithium line can act as a mass-dependent clock (Jeffries & Naylor 2001). By combining a measurement of the ...
constraints on grain formation around carbon stars
... laboratory study of presolar grains has emerged as a rich complementary source of information not only about its nature but about the conditions of its formation. Presolar grains are found in primitive meteorites and interplanetary dust particles, and are minerals that condensed prior to the formati ...
... laboratory study of presolar grains has emerged as a rich complementary source of information not only about its nature but about the conditions of its formation. Presolar grains are found in primitive meteorites and interplanetary dust particles, and are minerals that condensed prior to the formati ...
Subrahmanyan Chandrasekhar
... Traveling by ship in 1930 to begin his Ph.D. at Cambridge University, he had calculated a number. In his honor this number is now called The Chandrasekhar Limit: its value is 1.4. This number determines the fate of stars. Chandrasekhar published his result in 1931 in the Astrophysical Journal. In se ...
... Traveling by ship in 1930 to begin his Ph.D. at Cambridge University, he had calculated a number. In his honor this number is now called The Chandrasekhar Limit: its value is 1.4. This number determines the fate of stars. Chandrasekhar published his result in 1931 in the Astrophysical Journal. In se ...
cosmic-ray neon, wolf-rayet stars, and the superbubble origin of
... 2001); and (3) these W-R stars enrich the Galaxy locally in 22 Ne (Meynet & Maeder 1997; Maeder & Meynet 1993). This model predicts a 22 Ne/ 20 Ne ratio that has a weak energy dependence, increasing with energy from 1 to 100 GeV nucleon1. This energy dependence results from the W-R/OB gradient comb ...
... 2001); and (3) these W-R stars enrich the Galaxy locally in 22 Ne (Meynet & Maeder 1997; Maeder & Meynet 1993). This model predicts a 22 Ne/ 20 Ne ratio that has a weak energy dependence, increasing with energy from 1 to 100 GeV nucleon1. This energy dependence results from the W-R/OB gradient comb ...
Preliminary results of the Be stars proportion in LMC open
... Be phenomenon is transient. Be stars are fast rotators, reaching ~80% of their angular critical velocity. The fast rotation is a major factor in the matter ejection leading to the circumstellar disk and the emission, however it cannot explain alone the matter ejection and other mechanisms such as a ...
... Be phenomenon is transient. Be stars are fast rotators, reaching ~80% of their angular critical velocity. The fast rotation is a major factor in the matter ejection leading to the circumstellar disk and the emission, however it cannot explain alone the matter ejection and other mechanisms such as a ...
Why do some galaxies stop making new stars?
... versus those that are not? Easy. You look for stars But the spectra of red spiral galaxies identified by van den Bergh and Masters show the distinctive that die young. glow of hydrogen gas surrounding hot blue stars. These galaxies must still be forming new stars. Our yellowish sun is about halfway ...
... versus those that are not? Easy. You look for stars But the spectra of red spiral galaxies identified by van den Bergh and Masters show the distinctive that die young. glow of hydrogen gas surrounding hot blue stars. These galaxies must still be forming new stars. Our yellowish sun is about halfway ...
presentation
... Dust formation zone not well constrained (baselines were too long). Better (u,v) coverage with ATs. O-rich Miras: MIDI/AT program on 3 Miras C-rich Miras: MIDI+VISIR+AMBER program on 1 Mira Non-Mira AGB stars (majority of AGB stars) ...
... Dust formation zone not well constrained (baselines were too long). Better (u,v) coverage with ATs. O-rich Miras: MIDI/AT program on 3 Miras C-rich Miras: MIDI+VISIR+AMBER program on 1 Mira Non-Mira AGB stars (majority of AGB stars) ...
X-ray Binaries
... of the neutron star mass distribution in HMXBs are found to agree with theoretical expectations of core-collapse supernovae [60]. Constraints on neutron star forming supernovae do seem to be provided by two distinct populations of X-ray pulsars in Be/X-ray binaries; short Pspin pulsars with short or ...
... of the neutron star mass distribution in HMXBs are found to agree with theoretical expectations of core-collapse supernovae [60]. Constraints on neutron star forming supernovae do seem to be provided by two distinct populations of X-ray pulsars in Be/X-ray binaries; short Pspin pulsars with short or ...
... The role of magnetic fields received a boost with the finding of well-ordered fields along the polar outflow axis in CRL 618 and OH 231+04.1 (Sabin et al. 2014b), from dust polarization. Silicate dust shows higher polarization than carbon dust. The expansion of the jets in CRL 618 was reanalyzed using H ...
Cosmology
... 1930s Bethe & others: Sun heated by nuclear fusion 1938 Weizsacher: Stars NOT hot enough to cook up elements There must be a very-high-temperature “fire ball”. ...
... 1930s Bethe & others: Sun heated by nuclear fusion 1938 Weizsacher: Stars NOT hot enough to cook up elements There must be a very-high-temperature “fire ball”. ...
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.