Stellar Structure and Evolution
... The present notes grew out of an introductory course in stellar evolution which I have given for several years to third-year undergraduate students in physics at the University of Aarhus. The goal of the course and the notes is to show how many aspects of stellar evolution can be understood relative ...
... The present notes grew out of an introductory course in stellar evolution which I have given for several years to third-year undergraduate students in physics at the University of Aarhus. The goal of the course and the notes is to show how many aspects of stellar evolution can be understood relative ...
astronomical oxygen isotopic evidence for supernova
... with that of the solar system (on the order of hundreds of astronomical units). By embodying an entirely different scale of observation and an independent method of measurement, these new data should circumvent sampling bias and/or systematic errors that might be present in the radio emission result ...
... with that of the solar system (on the order of hundreds of astronomical units). By embodying an entirely different scale of observation and an independent method of measurement, these new data should circumvent sampling bias and/or systematic errors that might be present in the radio emission result ...
black holes are created when stars collapse and die from burning its
... • as long as a black hole has material to pull into to its core to provide energy, it will continue to grow • the process of pulling matter into its core releases a giant amount of energy, which causes surrounding material to disperse, so it doesn’t grow as fast • once all the starts burn out in 10 ...
... • as long as a black hole has material to pull into to its core to provide energy, it will continue to grow • the process of pulling matter into its core releases a giant amount of energy, which causes surrounding material to disperse, so it doesn’t grow as fast • once all the starts burn out in 10 ...
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 ...
Infrared Photometry of Red Supergiants in Young Clusters in the
... parameter with in each model hence its value is potentially a resting place for the effects of assumptions and uncertainties within the particular model. To investigate the model dependence of αP we show the models of Schaerer et al (1993) and Charbonnel et al. (1993) (hereafter the Geneva group). W ...
... parameter with in each model hence its value is potentially a resting place for the effects of assumptions and uncertainties within the particular model. To investigate the model dependence of αP we show the models of Schaerer et al (1993) and Charbonnel et al. (1993) (hereafter the Geneva group). W ...
constraints on grain formation around carbon stars
... take this as the minimum mass for stars of any kind that could have contributed grains to the solar nebula. We also adopt 1.1 M as the benchmark for carbon stars that could have produced presolar graphite. However, we note that the mass range in which carbon stars are capable of forming is thought ...
... take this as the minimum mass for stars of any kind that could have contributed grains to the solar nebula. We also adopt 1.1 M as the benchmark for carbon stars that could have produced presolar graphite. However, we note that the mass range in which carbon stars are capable of forming is thought ...
Starburst Galaxies Encyclopedia of Astronomy & Astrophysics eaa.iop.org T Heckman
... hydrogen). The production of these ionizing photons is dominated by the most massive, shortest-lived stars (M > 25M and lifetimes less than 7 million years). Measurements of Q are based on measurements of the rate at which H ions and electrons recombine, which in turn is measured by the luminosity ...
... hydrogen). The production of these ionizing photons is dominated by the most massive, shortest-lived stars (M > 25M and lifetimes less than 7 million years). Measurements of Q are based on measurements of the rate at which H ions and electrons recombine, which in turn is measured by the luminosity ...
Planet-Mediated Precision-Reconstruction of the Evolution of the
... HU Aquarii opens unusual opportunities for understanding the formation and evolution of this system. In particular the orbital parameters of the planets constrains the past and enables us to reconstruct the evolution of the system through the common-envelope phase. During this dramatic event the ent ...
... HU Aquarii opens unusual opportunities for understanding the formation and evolution of this system. In particular the orbital parameters of the planets constrains the past and enables us to reconstruct the evolution of the system through the common-envelope phase. During this dramatic event the ent ...
Boson Stars: Alternatives to primordial black holes?
... mass of the W boson would be small. Above 1.2 TeV/c2 , however, the self–interaction U (Φ) of the Higgs field is so large that the perturbative approach of the standard model becomes unreliable. Therefore a conformal extension of the standard model with gravity included could be necessary, see [35]. ...
... mass of the W boson would be small. Above 1.2 TeV/c2 , however, the self–interaction U (Φ) of the Higgs field is so large that the perturbative approach of the standard model becomes unreliable. Therefore a conformal extension of the standard model with gravity included could be necessary, see [35]. ...
Stellar Evolution - Astrophysics
... While mass, radius, luminosity and photospheric abundances characterise a star’s evolutionary state, the mass-loss rate is another critical parameter in the case of massive, binary and giant stars. The neutrino flux where it can be observed, as in the case of the Sun, gives vital information about c ...
... While mass, radius, luminosity and photospheric abundances characterise a star’s evolutionary state, the mass-loss rate is another critical parameter in the case of massive, binary and giant stars. The neutrino flux where it can be observed, as in the case of the Sun, gives vital information about c ...
Understanding Mass-Loss and the Late Evolution of Intermediate
... New Mexico, first light in 2010), with resolutions ranging from 0.1 to 100, can be used to probe the launch regions of CFWs in late AGB stars and PPNs, in particular the disk temperature, geometry and density structure. Direct imaging, with space-based telescopes such as HST and JWST will remain uns ...
... New Mexico, first light in 2010), with resolutions ranging from 0.1 to 100, can be used to probe the launch regions of CFWs in late AGB stars and PPNs, in particular the disk temperature, geometry and density structure. Direct imaging, with space-based telescopes such as HST and JWST will remain uns ...
Document
... • The sun is not powered by cooling! • Nuclear fusion – We understand the physics of this very well indeed • We can create fusion reactions on Earth! • We can measure the sun’s energy output • We know the processes causing this • We know how much fuel the sun has ...
... • The sun is not powered by cooling! • Nuclear fusion – We understand the physics of this very well indeed • We can create fusion reactions on Earth! • We can measure the sun’s energy output • We know the processes causing this • We know how much fuel the sun has ...
A Study of the Nature and Representative Features of Supernova
... The nature of supernovae was not initially understood. They were referred to as “guest stars” and seen as omens in a variety of cultures in Asian and European countries. Approximately 231 confirmed nearby (Galactic) supernovae remnants exist, with a few dozen other heavily suspected. For a listing a ...
... The nature of supernovae was not initially understood. They were referred to as “guest stars” and seen as omens in a variety of cultures in Asian and European countries. Approximately 231 confirmed nearby (Galactic) supernovae remnants exist, with a few dozen other heavily suspected. For a listing a ...
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.