Lecture 15
... begins to gravitationally collapse • Material from the molecular cloud falls on it, adding energy to its collapse • This raises the temperature ASTR111 Lecture 15 ...
... begins to gravitationally collapse • Material from the molecular cloud falls on it, adding energy to its collapse • This raises the temperature ASTR111 Lecture 15 ...
dm - The Institute of Mathematical Sciences
... When we see the night sky, it presents a picture of planets, stars, galaxies, and many other types of astronomical objects not necessarily visible to the naked eye. It is a picture of calm which hides the fact that the Universe is in fact fast expanding. This was first noted by Edwin Hubble in 1929. ...
... When we see the night sky, it presents a picture of planets, stars, galaxies, and many other types of astronomical objects not necessarily visible to the naked eye. It is a picture of calm which hides the fact that the Universe is in fact fast expanding. This was first noted by Edwin Hubble in 1929. ...
Nuclear and Particle Physics - Lecture 26 Nucleosynthesis 1
... release from fusion. In these cases, there are many different fusion reactions occuring and these steps are complex. They actually result in a whole range of nuclei up to iron, not just the carbon, oxygen, silicon and iron mentioned, although these are the most common. However, this does not mean no ...
... release from fusion. In these cases, there are many different fusion reactions occuring and these steps are complex. They actually result in a whole range of nuclei up to iron, not just the carbon, oxygen, silicon and iron mentioned, although these are the most common. However, this does not mean no ...
![Chapter 4 [PDF only] - Princeton University Press](http://s1.studyres.com/store/data/016931743_1-7c8ec22374457bf50a0a03f55488ddc7-300x300.png)
Chapter 4 [PDF only] - Princeton University Press
... The equations of pressure, opacity, and nuclear power density all depend sensitively on the abundances. Indeed, at some point, the hydrogen fuel in the core will be largely used up, and the star will lose the energy source that produces pressure, the gradient of which supports the star against gravi ...
... The equations of pressure, opacity, and nuclear power density all depend sensitively on the abundances. Indeed, at some point, the hydrogen fuel in the core will be largely used up, and the star will lose the energy source that produces pressure, the gradient of which supports the star against gravi ...
Presentation (PowerPoint File)
... Equation of state: isothermal or barotropic above 10^-14 g cm-3 Isothermal collapse results in many small fragments; barotropic collapse in a few. In no case did a massive star form (although simulation ran only until ~ 10% of mass had gone into stars). Require radiation-hydrodynamic simulations to ...
... Equation of state: isothermal or barotropic above 10^-14 g cm-3 Isothermal collapse results in many small fragments; barotropic collapse in a few. In no case did a massive star form (although simulation ran only until ~ 10% of mass had gone into stars). Require radiation-hydrodynamic simulations to ...
White Dwarf Stars
... ix billion years from now, someone looking up at the sky on a summer’s day would not see the same bright Sun we now see. In its place would be a tiny orb—a “white dwarf”—shining feebly in a black sky. Whether anyone will be around to see such an alien sky is another question: All life on Earth would ...
... ix billion years from now, someone looking up at the sky on a summer’s day would not see the same bright Sun we now see. In its place would be a tiny orb—a “white dwarf”—shining feebly in a black sky. Whether anyone will be around to see such an alien sky is another question: All life on Earth would ...
Resolved SPs : simulations
... The description of the details in the shape of the tracks, and the evolutionary lifetimes (use normalized independent variable) The description of photometric errors, blending and completeness (evaluate crowding conditions: if there is more than 1 star per resolution element the photometry is bad; c ...
... The description of the details in the shape of the tracks, and the evolutionary lifetimes (use normalized independent variable) The description of photometric errors, blending and completeness (evaluate crowding conditions: if there is more than 1 star per resolution element the photometry is bad; c ...
Abundance Anomalies In Tidal Disruption Events
... assume thermal line widths (∼ 10 km/s), far smaller than the observed line widths (> 103 km/s). Hence, for the same physical parameters, the lines are far less optically thick than assumed by the CLOUDY models. Roth et al. (2015), however, find that extreme hydrogen to helium line ratios are achieva ...
... assume thermal line widths (∼ 10 km/s), far smaller than the observed line widths (> 103 km/s). Hence, for the same physical parameters, the lines are far less optically thick than assumed by the CLOUDY models. Roth et al. (2015), however, find that extreme hydrogen to helium line ratios are achieva ...
QSOs . Continuum Radiation Energy Source
... Velocities of stars in very center 4 million M black hole at position of Sagittarius A* ...
... Velocities of stars in very center 4 million M black hole at position of Sagittarius A* ...
Stellar Relaxation Times
... center of the Galaxy is not gravitationally affected by other stars. On the other hand, giant molecular clouds have masses that are ~ 108 M. Although the number density of clouds is lower, it’s not 1016 times lower! The masses of these clouds are therefore high enough to scatter stars out of their ...
... center of the Galaxy is not gravitationally affected by other stars. On the other hand, giant molecular clouds have masses that are ~ 108 M. Although the number density of clouds is lower, it’s not 1016 times lower! The masses of these clouds are therefore high enough to scatter stars out of their ...
M-Dwarf Planet Occurrence in the Era of K2
... account for incompleteness–to infer from the visible popula?on what is there but could not be seen. We must understand the selec?vity in our detec?on sensi?vity to different types of planets around differen ...
... account for incompleteness–to infer from the visible popula?on what is there but could not be seen. We must understand the selec?vity in our detec?on sensi?vity to different types of planets around differen ...
Research News
... stops, the star is suddenly left with an inactive iron core, which produces no thermal pressure. Instantly, gravity forces the core’s electrons to combine with protons, forming neutrons, hence “neutron star”. Within seconds, this gravitational collapse releases more energy than the Sun will radiate ...
... stops, the star is suddenly left with an inactive iron core, which produces no thermal pressure. Instantly, gravity forces the core’s electrons to combine with protons, forming neutrons, hence “neutron star”. Within seconds, this gravitational collapse releases more energy than the Sun will radiate ...
From Big Bang to Biospheres: The Scope and Limits of Explanation
... – particle physics on the ground floor, then the rest of physics, then chemistry, and so forth: all the way up to psychology – and the economists in the penthouse. There is a corresponding hierarchy of complexity – atoms, molecules, cells, organisms, and so forth. But the analogy with a building is ...
... – particle physics on the ground floor, then the rest of physics, then chemistry, and so forth: all the way up to psychology – and the economists in the penthouse. There is a corresponding hierarchy of complexity – atoms, molecules, cells, organisms, and so forth. But the analogy with a building is ...
Lecture3
... • Further classification: 0 to 9 subclasses in each class. e.g., F0, F1, F2, ………….F9, etc. e.g., Sun is G2 star. ...
... • Further classification: 0 to 9 subclasses in each class. e.g., F0, F1, F2, ………….F9, etc. e.g., Sun is G2 star. ...
Astronomy 112: The Physics of Stars Class 3 Notes: Hydrostatic
... Before going on, it is worth pausing to think a bit about the coordinate system we made use of to derive this result, because it is one that we’re going to encounter over and over again throughout the class. Intuitively, the most natural way to think about stars is in terms of Eulerian coordinates. ...
... Before going on, it is worth pausing to think a bit about the coordinate system we made use of to derive this result, because it is one that we’re going to encounter over and over again throughout the class. Intuitively, the most natural way to think about stars is in terms of Eulerian coordinates. ...
Recent advances in star
... note that the calculations of Lim, Falle and Hartquist, which do attempt to be more realistic in terms of the microphysics, suggest that the gross macroscopic behaviour of the gas is greatly modified by its microscopic properties. The safest conclusion at present seems to be that we have not yet arr ...
... note that the calculations of Lim, Falle and Hartquist, which do attempt to be more realistic in terms of the microphysics, suggest that the gross macroscopic behaviour of the gas is greatly modified by its microscopic properties. The safest conclusion at present seems to be that we have not yet arr ...
Tolman–Oppenheimer–Volkoff (TOV) Stars
... time, a phenomenon made possible by the balance of internal pressure support against the star’s gravitational field. For stars like our sun the gas pressure is fueled by the hot nuclear reactions in its core. However, many types of stars are known to exist with varying mass and temperature as charac ...
... time, a phenomenon made possible by the balance of internal pressure support against the star’s gravitational field. For stars like our sun the gas pressure is fueled by the hot nuclear reactions in its core. However, many types of stars are known to exist with varying mass and temperature as charac ...
Effects of color superconductivity on the nucleation of
... (NLWM) & Quark Meson Coupling (QMC). We have explored the effect of different hyperon couplings on the critical mass and on the stellar conversion energy, finding that the increase of the hyperon coupling shift the bulk transition point for quark deconfinement to higher densities and makes the conve ...
... (NLWM) & Quark Meson Coupling (QMC). We have explored the effect of different hyperon couplings on the critical mass and on the stellar conversion energy, finding that the increase of the hyperon coupling shift the bulk transition point for quark deconfinement to higher densities and makes the conve ...
The Milky Way Galaxy
... Shapley determined the distances to a number of globular clusters using the period-luminosity law for Cepheids. He noted that most globular clusters had linear diameters of about 25 pc. He could then use their angular diameters to get approximate distance for clusters whose stars were too faint to ...
... Shapley determined the distances to a number of globular clusters using the period-luminosity law for Cepheids. He noted that most globular clusters had linear diameters of about 25 pc. He could then use their angular diameters to get approximate distance for clusters whose stars were too faint to ...
Open cluster intro
... measure stellar image taken with the two different filters. Download ImageJ and install it if you don’t already have it. Next download and install the astronomy plugin from the link on the cluster project page. When you download the astronomy plugins, you also will see a description of the toolbar a ...
... measure stellar image taken with the two different filters. Download ImageJ and install it if you don’t already have it. Next download and install the astronomy plugin from the link on the cluster project page. When you download the astronomy plugins, you also will see a description of the toolbar a ...
BINARY STARS
... between them. If the distance is large, we can guess that the force that keeps the bonding of the partners intact should be large. Second, we should observe the period of their dancing motion around each other. If the period is short, then the stars are spinning fast around each other, and the force ...
... between them. If the distance is large, we can guess that the force that keeps the bonding of the partners intact should be large. Second, we should observe the period of their dancing motion around each other. If the period is short, then the stars are spinning fast around each other, and the force ...
Scientific Background Paper: Iron`s Place and Role
... The stages of stellar evolution are determined by the mechanism used to limit the collapse of a star by producing an outward force to overcome the inward pull of gravity. The lifecycle of stars begins with the in-fall of a ball of gas and dust and their death is ultimately the failure to find a mech ...
... The stages of stellar evolution are determined by the mechanism used to limit the collapse of a star by producing an outward force to overcome the inward pull of gravity. The lifecycle of stars begins with the in-fall of a ball of gas and dust and their death is ultimately the failure to find a mech ...
Supersonic turbulence?
... • Problem: specific energy ~ u2 in macroscopic motions, length scale l gets converted to heat (cascading eddies, radiative shocks) in time ~ l/u. • Need u ~ virial speed and l << R for support. • But this means dissipation time l/u << crossing time R/u, so need constant replenishment (winds??) • Ord ...
... • Problem: specific energy ~ u2 in macroscopic motions, length scale l gets converted to heat (cascading eddies, radiative shocks) in time ~ l/u. • Need u ~ virial speed and l << R for support. • But this means dissipation time l/u << crossing time R/u, so need constant replenishment (winds??) • Ord ...
Catch a Star 2016 Title: The lost planet
... In such stellar system, any planet there will always be two forces of attraction: ...
... In such stellar system, any planet there will always be two forces of attraction: ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.