Document
... • Stellar evolution rather well understood • Stellar spectra computed from stellar model atmospheres → the galactic spectrum can be computed if one knows the number of stars as a function of their mass, chemical composition, evolution stage ...
... • Stellar evolution rather well understood • Stellar spectra computed from stellar model atmospheres → the galactic spectrum can be computed if one knows the number of stars as a function of their mass, chemical composition, evolution stage ...
Absolute Magnitudes of Turnoff Stars in Globular Clusters Palomar
... using high accuracy Hubble Space Telescope data, Piotto et al. (2012) recently showed that many globular clusters have more than one stellar population, visible from a broad subgiant branch (SBG) or distinct separation between multiple SGBs [4]. All of the stars begin on the main sequence of the HR ...
... using high accuracy Hubble Space Telescope data, Piotto et al. (2012) recently showed that many globular clusters have more than one stellar population, visible from a broad subgiant branch (SBG) or distinct separation between multiple SGBs [4]. All of the stars begin on the main sequence of the HR ...
Abundance Trends of Alpha and Fe
... of only a handful of neutron-capture elements are normally reported in the cluster literature. Chief among these are Ba and La (prime representatives of the s-process), and Eu (the main representative of the r-process). In Sneden et al. (2003) and Gratton et al. (2004) various correlations of relati ...
... of only a handful of neutron-capture elements are normally reported in the cluster literature. Chief among these are Ba and La (prime representatives of the s-process), and Eu (the main representative of the r-process). In Sneden et al. (2003) and Gratton et al. (2004) various correlations of relati ...
Spectral Matching for Elemental Abundances of Evolved Stars of Globular Clusters
... Sky location of the stars of the different datasets of 47 Tuc. . . . . . . . . . . . . . . . . . . . . . . . . . . CMD of the 94 stars of 47 Tuc from AAOmega. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AAOmega spectrum of Lee 2525. . . . . . . . . . . . . . . . . . . . . . . . . ...
... Sky location of the stars of the different datasets of 47 Tuc. . . . . . . . . . . . . . . . . . . . . . . . . . . CMD of the 94 stars of 47 Tuc from AAOmega. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AAOmega spectrum of Lee 2525. . . . . . . . . . . . . . . . . . . . . . . . . ...
View - ESA
... The first part of this report addresses the preliminary phase in which information about the Solar Neighborhood has been collected. This part has been particularly time consuming since the data sources are many and generally incomplete in several respects, making it necessary to merge information of ...
... The first part of this report addresses the preliminary phase in which information about the Solar Neighborhood has been collected. This part has been particularly time consuming since the data sources are many and generally incomplete in several respects, making it necessary to merge information of ...
MS Word
... order to keep the range of velocities between 1 and 100 on the x-axis of the graph, you may wish to convert each velocity from centimeters to meters (simply divide by 100). 18. In what way does velocity matter? (i.e., describe the plot) ...
... order to keep the range of velocities between 1 and 100 on the x-axis of the graph, you may wish to convert each velocity from centimeters to meters (simply divide by 100). 18. In what way does velocity matter? (i.e., describe the plot) ...
Student Manual - Gettysburg College
... shrink, and the density, pressure, and temperature are highest at the center. Eventually, the temperature and pressure in the collapsing core get so high that hydrogen atoms can fuse together, forming helium. This fusion process releases a huge amount of energy, which heats up the gas and stops the ...
... shrink, and the density, pressure, and temperature are highest at the center. Eventually, the temperature and pressure in the collapsing core get so high that hydrogen atoms can fuse together, forming helium. This fusion process releases a huge amount of energy, which heats up the gas and stops the ...
Gamma - Ray Observations of Olaf Reimer
... Binary systems of a compact object (neutron star or black hole) and a stellar companion Matter is flowing over from the stellar companion onto the compact object. Angular momentum conservation => Formation of an accretion disk Matter in the accretion disk heats up to ~ 106 K => X-ray emission ...
... Binary systems of a compact object (neutron star or black hole) and a stellar companion Matter is flowing over from the stellar companion onto the compact object. Angular momentum conservation => Formation of an accretion disk Matter in the accretion disk heats up to ~ 106 K => X-ray emission ...
Starburst Galaxies - Beck-Shop
... 80% have masses less than that of the Sun. The higher mass stars are thus few and far between, but their brightnesses are out of all proportion greater than those of the lower mass stars – a star with a mass half that of the Sun will have a luminosity about 3% that of the Sun, while a five solar-mas ...
... 80% have masses less than that of the Sun. The higher mass stars are thus few and far between, but their brightnesses are out of all proportion greater than those of the lower mass stars – a star with a mass half that of the Sun will have a luminosity about 3% that of the Sun, while a five solar-mas ...
Shock?heating of stellar envelopes: a possible common mechanism
... reader to WHW02 for a discussion of the physics included in such models. These physically consistent models give envelope structures that obey the equations and principles of stellar structure and evolution. The exact details of these models are not relevant since we aim at developing a general, qua ...
... reader to WHW02 for a discussion of the physics included in such models. These physically consistent models give envelope structures that obey the equations and principles of stellar structure and evolution. The exact details of these models are not relevant since we aim at developing a general, qua ...
Supervisors
... of very strong spectral lines, it can even depend on whether all of the line or only its wings are used. For example, Przybilla et al. (2011) showed that the LTE model ATLAS9/SYNTHE (Kurucz, 1993; Kurucz and Avrett, 1981) can be used to determine the parameters of stars with effective temperatures 1 ...
... of very strong spectral lines, it can even depend on whether all of the line or only its wings are used. For example, Przybilla et al. (2011) showed that the LTE model ATLAS9/SYNTHE (Kurucz, 1993; Kurucz and Avrett, 1981) can be used to determine the parameters of stars with effective temperatures 1 ...
ONE- AND MULTI- ZONE MODELS: Chemical properties
... infall and gas depletion by star formation gives rise to a non monotonic time dependence of the star formation rate which instead of steadily decreasing from the initial stage as in the closed-box model starts small, increase to a peak value, and than declines over a time scale which is a sizable fr ...
... infall and gas depletion by star formation gives rise to a non monotonic time dependence of the star formation rate which instead of steadily decreasing from the initial stage as in the closed-box model starts small, increase to a peak value, and than declines over a time scale which is a sizable fr ...
... The expansion of the jets in CRL 618 was reanalyzed using HST images by Riera et al. (2014): they find a Hubble-type flow. The mirror symmetry in the lobes of CRL 618 may show indications of alternate ejection in the two polar directions (Velázquez et al. 2014), caused by one-sided heating of the acc ...
Orbital period decay of compact black hole X
... detailed evolutionary sequences of a BHXB with an initial orbital period of 0.9 d, which consist of a 5.0 M BH and a 3.0 M donor star. The calculation shows that if the fraction of the transferred mass feeds into the circumbinary disk δ is greater than 0.00035, the mass transfer becomes dynamicall ...
... detailed evolutionary sequences of a BHXB with an initial orbital period of 0.9 d, which consist of a 5.0 M BH and a 3.0 M donor star. The calculation shows that if the fraction of the transferred mass feeds into the circumbinary disk δ is greater than 0.00035, the mass transfer becomes dynamicall ...
General relativistic spectra of accretion discs around rapidly
... Accepted 2001 February 21. Received 2001 February 21; in original form 2000 October 12 ...
... Accepted 2001 February 21. Received 2001 February 21; in original form 2000 October 12 ...
Population synthesis for double white dwarfs. I. Close - UvA-DARE
... CO white dwarf is formed first. It starts with a more extreme mass ratio and a relatively wide orbit, which shrinks in a phase of envelope ejection. The secondary does not accrete anything and fills its Roche lobe when it ascends the first giant branch, having a degenerate helium core. It then evolv ...
... CO white dwarf is formed first. It starts with a more extreme mass ratio and a relatively wide orbit, which shrinks in a phase of envelope ejection. The secondary does not accrete anything and fills its Roche lobe when it ascends the first giant branch, having a degenerate helium core. It then evolv ...
SherwoodWA_1973redux - Edinburgh Research Archive
... which have been adapted for this thesis by Herr W. David Cooper and ...
... which have been adapted for this thesis by Herr W. David Cooper and ...
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.