Formation and Disruption of Cosmological Low Mass Objects
... the intergalactic medium and the presence of heavy elements at high-z suggest that there are other population of luminous objects, which precedes normal galaxies. Thus, theoretical approach to reveal the formation mechanism of the such unseen luminous objects is very important. It is now widely acce ...
... the intergalactic medium and the presence of heavy elements at high-z suggest that there are other population of luminous objects, which precedes normal galaxies. Thus, theoretical approach to reveal the formation mechanism of the such unseen luminous objects is very important. It is now widely acce ...
THE FUTURE IS NOW: THE FORMATION OF SINGLE LOW
... ABSTRACT Low-mass helium-core white dwarfs (M < 0:45 M ) can be produced from interacting binary systems, and traditionally all of them have been attributed to this channel. However, a low-mass white dwarf could also result from a single star that experiences severe mass loss on the first ascent gi ...
... ABSTRACT Low-mass helium-core white dwarfs (M < 0:45 M ) can be produced from interacting binary systems, and traditionally all of them have been attributed to this channel. However, a low-mass white dwarf could also result from a single star that experiences severe mass loss on the first ascent gi ...
Bildungskonzepte von Galaxien - uni
... Stellar dynamics (2): Contracting galaxy: two extreme cases Potentials changing slowly Eccentricity is invariant Potentials changing rapidly Eccentricity increase with mass concentration Thus Angular momentum conserved Slow potential change: eccentricity is conserved, height above ...
... Stellar dynamics (2): Contracting galaxy: two extreme cases Potentials changing slowly Eccentricity is invariant Potentials changing rapidly Eccentricity increase with mass concentration Thus Angular momentum conserved Slow potential change: eccentricity is conserved, height above ...
Surface temperature distribution and absorption features in Isolated
... nuclei to form helium. When H is spent in the core, He starts to be burnt at ∼ 108 K producing oxygen and carbon. A star of initial mass above 8 M is able to ignite O and C in order to produce heavier elements, such as neon and silicon. The star internal temperature increases and burning continues ...
... nuclei to form helium. When H is spent in the core, He starts to be burnt at ∼ 108 K producing oxygen and carbon. A star of initial mass above 8 M is able to ignite O and C in order to produce heavier elements, such as neon and silicon. The star internal temperature increases and burning continues ...
Large-eddy simulations of isolated disc galaxies with thermal and
... Miura et al. 2012) before they are destroyed by supernova explosions (SNe) and stellar winds. Actively star-forming molecular clouds are known to be strongly supersonically turbulent with typical velocity dispersions around 10 km s−1 (e.g. Leroy et al. 2008; Stilp et al. 2013), or larger in interact ...
... Miura et al. 2012) before they are destroyed by supernova explosions (SNe) and stellar winds. Actively star-forming molecular clouds are known to be strongly supersonically turbulent with typical velocity dispersions around 10 km s−1 (e.g. Leroy et al. 2008; Stilp et al. 2013), or larger in interact ...
Document
... 1938 H. A. Bethe and C. L. Critchfield: “The formation of deuterons by proton combination” ...
... 1938 H. A. Bethe and C. L. Critchfield: “The formation of deuterons by proton combination” ...
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 ...
observingglobularclusters
... 2. Follow the line to the next bright star to the West, called Muphrid. 3. Now locate Alpha Coma Berenices, the bottom of the right triangle M53 is above and to the left of Alpha Coma Berenices. Nudge the scope up and eastward to find it. The pair of stars in the wide field help you confirm you have ...
... 2. Follow the line to the next bright star to the West, called Muphrid. 3. Now locate Alpha Coma Berenices, the bottom of the right triangle M53 is above and to the left of Alpha Coma Berenices. Nudge the scope up and eastward to find it. The pair of stars in the wide field help you confirm you have ...
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... by considering the stellar wind. Our method provides a fast means to assess which planets are most affected by the stellar magnetic field, which can be used as a first study to be followed by more sophisticated models. We show that hypothetical Earth-like planets with similar terrestrial magnetisati ...
... by considering the stellar wind. Our method provides a fast means to assess which planets are most affected by the stellar magnetic field, which can be used as a first study to be followed by more sophisticated models. We show that hypothetical Earth-like planets with similar terrestrial magnetisati ...
Photometric transit search for planets around cool stars from the
... stellar evolutionary models the detailed treatment of the effects of non-zero magnetic fields on the properties of low-mass stars (e.g., Mullan & McDonald 2001; Ribas 2006; Torres et al. 2010, and references therein), has significant repercussions on the inferred composition of the planet. An import ...
... stellar evolutionary models the detailed treatment of the effects of non-zero magnetic fields on the properties of low-mass stars (e.g., Mullan & McDonald 2001; Ribas 2006; Torres et al. 2010, and references therein), has significant repercussions on the inferred composition of the planet. An import ...
Manuscript - Kapteyn Astronomical Institute
... Md = 0.008 and 0.04 × Mvir , and are embedded in a Hernquist halo with mass Mvir = 1010 h−1 M⊙ , and scale-radius a = 9.3 kpc, i.e. ηgal ∼ 5% and 23% respectively. The disks are radially exponential with scale-length Rd = 0.67h−1 kpc, and vertically they follow sech2 (z/2z0 ), with z0 = 0.05Rd . The ...
... Md = 0.008 and 0.04 × Mvir , and are embedded in a Hernquist halo with mass Mvir = 1010 h−1 M⊙ , and scale-radius a = 9.3 kpc, i.e. ηgal ∼ 5% and 23% respectively. The disks are radially exponential with scale-length Rd = 0.67h−1 kpc, and vertically they follow sech2 (z/2z0 ), with z0 = 0.05Rd . The ...
Dynamics of the Milky Way
... • Relaxation is expected to have occurred in some globular clusters and the densest nuclei of galaxies Dynamics of the Milky Way --- Part 1: Introduction and Fundamental Stellar Dynamics ...
... • Relaxation is expected to have occurred in some globular clusters and the densest nuclei of galaxies Dynamics of the Milky Way --- Part 1: Introduction and Fundamental Stellar Dynamics ...
Abstracts - Space Telescope Science Institute
... Universe. After Servicing Mission 4, the study of YSCs has been revived. The access to sensitive UV detectors with a large field of view has allowed to survey wider samples of cluster populations. The inclusion of the U-band is crucial for cluster analysis because it breaks the degeneracy between ag ...
... Universe. After Servicing Mission 4, the study of YSCs has been revived. The access to sensitive UV detectors with a large field of view has allowed to survey wider samples of cluster populations. The inclusion of the U-band is crucial for cluster analysis because it breaks the degeneracy between ag ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.