L12 - QUB Astrophysics Research Centre
... Mn and Rn are constants that vary with polytropic index n (from solution of ...
... Mn and Rn are constants that vary with polytropic index n (from solution of ...
@let@token Stellar Oscillations: Pulsations of Stars Throughout the
... A more careful derivation (including density perturbations in the quasi-adiabatic approximation) shows that the condition for local driving due to the Kappa-gamma mechanism is actually ...
... A more careful derivation (including density perturbations in the quasi-adiabatic approximation) shows that the condition for local driving due to the Kappa-gamma mechanism is actually ...
Slide 1
... Turn Off - As the hydrogen fuel in a star's core runs out the core begins to collapse due to gravity and the star moves away from the main sequence. At the turn off nearly all the central fuel is gone. Red Giant Branch - When the central fuel is gone, hydrogen starts to burn in an envelope around a ...
... Turn Off - As the hydrogen fuel in a star's core runs out the core begins to collapse due to gravity and the star moves away from the main sequence. At the turn off nearly all the central fuel is gone. Red Giant Branch - When the central fuel is gone, hydrogen starts to burn in an envelope around a ...
TO THE STATISTICS OF DOUBLE STARS It was indicated by a
... equilibrium between double and single stars, leads to an upper age bound of 1010 years for the ensemble of double stars. 1. Distribution of eccentricities of the double star orbits The distribution of eccentricities of double star orbits was discussed often enough. Namely it was established, that am ...
... equilibrium between double and single stars, leads to an upper age bound of 1010 years for the ensemble of double stars. 1. Distribution of eccentricities of the double star orbits The distribution of eccentricities of double star orbits was discussed often enough. Namely it was established, that am ...
The Life of a Star
... For the Sun, KH = 1:6 10 yrs (L = 3:827 1033 erg s 1 ). This implies that the Sun could shine only for about 10 million years, if the reactions at the center would be switched o . Stars evolve { in most cases { on much longer timescales, because they have energy sources much larger than jEg j. ...
... For the Sun, KH = 1:6 10 yrs (L = 3:827 1033 erg s 1 ). This implies that the Sun could shine only for about 10 million years, if the reactions at the center would be switched o . Stars evolve { in most cases { on much longer timescales, because they have energy sources much larger than jEg j. ...
Morphological characteristics of OB spectra and environments
... subregions, ranging from the pure dust/IR sources through, consecutively, centrally concentrated H II regions, giant shells, and dissipating nebulosities, to a region of bright blue stars and possibly red supergiants without any nebulosity. The intensity of the IR emission in the Spitzer images decl ...
... subregions, ranging from the pure dust/IR sources through, consecutively, centrally concentrated H II regions, giant shells, and dissipating nebulosities, to a region of bright blue stars and possibly red supergiants without any nebulosity. The intensity of the IR emission in the Spitzer images decl ...
The Milky Way II AST 112
... • The disk is full of hydrogen gas. The bulge doesn’t have much. • We see hydrogen clouds at high latitudes that are falling down onto the disk – This supports the galactic fountain idea! ...
... • The disk is full of hydrogen gas. The bulge doesn’t have much. • We see hydrogen clouds at high latitudes that are falling down onto the disk – This supports the galactic fountain idea! ...
Document
... long P, high amplitude High density short P, low amplitude Density profile decides how deep the pulsations penetrate in the star. ...
... long P, high amplitude High density short P, low amplitude Density profile decides how deep the pulsations penetrate in the star. ...
protostellar disks under the influence of winds and uv radiation
... within a dusty shroud and, if they are, could be interpreted as ultracompact HII (UCHII) regions. The lifetime of this configuration and the radio flux depend on the proximity and UV flux of the ionizing source. The most prominent UCHII regions will arise from disks extremely close to the UV source, ...
... within a dusty shroud and, if they are, could be interpreted as ultracompact HII (UCHII) regions. The lifetime of this configuration and the radio flux depend on the proximity and UV flux of the ionizing source. The most prominent UCHII regions will arise from disks extremely close to the UV source, ...
Parameters of massive stars in the Milky Way and nearby galaxies
... atmospheres that include sphericity, mass-loss and line-blanketing, in addition to NLTE. The combination of all these factors results in temperatures that are much cooler than those hitherto assumed. Vacca et al. (1996) presented a compilation of the spectroscopic determinations of effective temper ...
... atmospheres that include sphericity, mass-loss and line-blanketing, in addition to NLTE. The combination of all these factors results in temperatures that are much cooler than those hitherto assumed. Vacca et al. (1996) presented a compilation of the spectroscopic determinations of effective temper ...
Anna Frebel nucleosynthesis, stars + chemical evolution
... Chemical “fingerprint” of previous nucleosynthesis event (only “visible” in the oldest stars because of low metallicity) ~5% of metal-poor stars with [Fe/H] < 2.5 (Barklem et al. 05) Only 15-20 stars known so ...
... Chemical “fingerprint” of previous nucleosynthesis event (only “visible” in the oldest stars because of low metallicity) ~5% of metal-poor stars with [Fe/H] < 2.5 (Barklem et al. 05) Only 15-20 stars known so ...
Please Highlight this Area and Add your Main Title
... methodology and the photometric light curves seen above were created. The important piece of data that can be extracted from the photometric light curve is the periodicity of the variable star. The periodicity of any variable star describes the time it takes to change from least magnitude to greates ...
... methodology and the photometric light curves seen above were created. The important piece of data that can be extracted from the photometric light curve is the periodicity of the variable star. The periodicity of any variable star describes the time it takes to change from least magnitude to greates ...
Origin of close binary systems
... - example: the multiplicities of the Orion Trapezium stars and the companion star frequency of high-mass vs. low-mass stars - SPH simulations: hierarchical star cluster formation and the merging of subclusters as a model for the origin of Trapezia - origin due to formation or early dynamical N-body ...
... - example: the multiplicities of the Orion Trapezium stars and the companion star frequency of high-mass vs. low-mass stars - SPH simulations: hierarchical star cluster formation and the merging of subclusters as a model for the origin of Trapezia - origin due to formation or early dynamical N-body ...
Investigating the Structure of Electroweak Stars
... only be prevented from collapsing upon themselves by the huge amount of energy released by the baryon number violating interactions going on in the core. A static solution for such a star has been calculated, but it remains to be seen whether such stars are stable. This project investigates the stru ...
... only be prevented from collapsing upon themselves by the huge amount of energy released by the baryon number violating interactions going on in the core. A static solution for such a star has been calculated, but it remains to be seen whether such stars are stable. This project investigates the stru ...
Counter-rotating Stellar Components in Simulated Disk Galaxies
... major axis shows striking bimodality. This bimodality indicates the presence of two disk components, photometrically inseparable, but counterstreaming at projected velocities of 100km/s and +150km/s (Rix et al 1992) ...
... major axis shows striking bimodality. This bimodality indicates the presence of two disk components, photometrically inseparable, but counterstreaming at projected velocities of 100km/s and +150km/s (Rix et al 1992) ...
Spots on Ap Stars
... observed line profile, one can construct an image of the surface of the star. This technique has been applied to many different types of stars. ...
... observed line profile, one can construct an image of the surface of the star. This technique has been applied to many different types of stars. ...
The First Stars in the Universe
... not emit radiation or lose energy, they would remain scattered in the primordial cloud. Thus, the starforming system would come to resemble a miniature galaxy, with a disk of ordinary matter and a halo of dark matter. Inside the disk, the densest clumps of gas would continue to contract, and eventu ...
... not emit radiation or lose energy, they would remain scattered in the primordial cloud. Thus, the starforming system would come to resemble a miniature galaxy, with a disk of ordinary matter and a halo of dark matter. Inside the disk, the densest clumps of gas would continue to contract, and eventu ...
Massive star evolution: luminous blue variables as unexpected
... LBVs (e.g. Clark et al. 2009). The 25 M model predicts a more chemically enriched surface with He and N (0.92 and 0.016 by mass fraction, respectively) and, as expected, its spectrum shows stronger He I and N II lines than that of the 20 M model or the LBV observations. Still, the 25 M model spec ...
... LBVs (e.g. Clark et al. 2009). The 25 M model predicts a more chemically enriched surface with He and N (0.92 and 0.016 by mass fraction, respectively) and, as expected, its spectrum shows stronger He I and N II lines than that of the 20 M model or the LBV observations. Still, the 25 M model spec ...
Oxygen production on the AGB and the relevance of planetary
... • After each He-shell flash, the base of the envelope may “dredge” into the intershell region " third dredge-up • This can lead to carbon star production, where C/O > 1 at the stellar surface • Correlated with an enrichment of heavy elements (s-process) Standard picture: Dominant process in stars ...
... • After each He-shell flash, the base of the envelope may “dredge” into the intershell region " third dredge-up • This can lead to carbon star production, where C/O > 1 at the stellar surface • Correlated with an enrichment of heavy elements (s-process) Standard picture: Dominant process in stars ...
What keeps stars shining? What holds them up? Lecture 14. The
... converted to energy by famous equation E = Mc2. More later) Stability: Why doesn't all the Hydrogen in the Universe spontaneously fuse in a humongous Hydrogen Bomb? The hydrogen nuclei (pure protons) in the first step have positive charge, so they push each other away. Must slam them together very h ...
... converted to energy by famous equation E = Mc2. More later) Stability: Why doesn't all the Hydrogen in the Universe spontaneously fuse in a humongous Hydrogen Bomb? The hydrogen nuclei (pure protons) in the first step have positive charge, so they push each other away. Must slam them together very h ...
Unresolved Stellar Populations
... Let us first see a few general trends: • An SSP generally fades and becomes redder with increasing age due to the decrease of the MS extension and He-burning luminosity. These general trends are briefly interrupted, especially when the K band is involved, by the appearance of a large number of red H ...
... Let us first see a few general trends: • An SSP generally fades and becomes redder with increasing age due to the decrease of the MS extension and He-burning luminosity. These general trends are briefly interrupted, especially when the K band is involved, by the appearance of a large number of red H ...
12C13C1414N21312C/13C3he43He/4He Sub-surface
... zones achieve higher velocities. For a quantitative analysis, we define an average convective velocity where is the upper boundary of the convective zone, and where we set α = 1.5. From Figures 2 and 3, three trends for the extent of the sub-surface convection zones are noticeable. First, with incre ...
... zones achieve higher velocities. For a quantitative analysis, we define an average convective velocity where is the upper boundary of the convective zone, and where we set α = 1.5. From Figures 2 and 3, three trends for the extent of the sub-surface convection zones are noticeable. First, with incre ...
15.1 Introduction
... makes a number of excursions to and fro across the HR diagram. In highmass stars, these rightward (core exhaustion) and leftward (core ignition) excursions, between the red and blue (supergiant) branches respectively, occur with only a slight systematic increase in luminosity. Thus, the evolutionary ...
... makes a number of excursions to and fro across the HR diagram. In highmass stars, these rightward (core exhaustion) and leftward (core ignition) excursions, between the red and blue (supergiant) branches respectively, occur with only a slight systematic increase in luminosity. Thus, the evolutionary ...
