AS2001 - University of St Andrews
... Quark + antiquark annihilation photon/baryon ratio The quark soup heavy quark decay Quark-Hadron phase transition and neutron decay n/p ratio Big Bang nucleosynthesis primordial abundances ...
... Quark + antiquark annihilation photon/baryon ratio The quark soup heavy quark decay Quark-Hadron phase transition and neutron decay n/p ratio Big Bang nucleosynthesis primordial abundances ...
PH607 – Galaxies
... medium strongly absorbs X-rays, and cold clouds of interstellar gas are seen as shadows against background X-ray emission. Gamma rays 1: photon energies greater than 300 MeV. At these extreme energies, most of the celestial gamma rays originate in collisions of cosmic rays with hydrogen nuclei in in ...
... medium strongly absorbs X-rays, and cold clouds of interstellar gas are seen as shadows against background X-ray emission. Gamma rays 1: photon energies greater than 300 MeV. At these extreme energies, most of the celestial gamma rays originate in collisions of cosmic rays with hydrogen nuclei in in ...
Assignment 2
... Problem 5. Two point particles each have a mass m. Initially they are held apart a distance d away from each other and are initially both at rest. How they are let go, and due to the gravitational force they are attracted to each other. What is their speed when they are a distance d/2 apart? Expres ...
... Problem 5. Two point particles each have a mass m. Initially they are held apart a distance d away from each other and are initially both at rest. How they are let go, and due to the gravitational force they are attracted to each other. What is their speed when they are a distance d/2 apart? Expres ...
SS_L4
... approximately parallel to the galactic plane. Field strongly tied to the ionized plasma in the ISM. Small local perturbations in the field lead to local potential wells. ISM condenses in these wells, increasing their strength as it pulls the magnetic field with it Rayleigh-Taylor instability. Prov ...
... approximately parallel to the galactic plane. Field strongly tied to the ionized plasma in the ISM. Small local perturbations in the field lead to local potential wells. ISM condenses in these wells, increasing their strength as it pulls the magnetic field with it Rayleigh-Taylor instability. Prov ...
Stars with Great Attraction - Max-Planck
... for Astrophysics aren’t really interested in fiction, as magnetars are exciting enough for science, as well. The objects have a turbulent history. They form upon the spectacular death of a sun, a supernova, when a star with a mass of between 8 and 20 solar masses has gotten itself into an energy cri ...
... for Astrophysics aren’t really interested in fiction, as magnetars are exciting enough for science, as well. The objects have a turbulent history. They form upon the spectacular death of a sun, a supernova, when a star with a mass of between 8 and 20 solar masses has gotten itself into an energy cri ...
The first stars, as seen by supercomputers
... Figure 1. The gathering place. These six panels show density (top; red is less dense; yellow, denser) and temperature (bottom; red is 10 K; yellow, 1000 K) profiles of gas that falls into dark-matter gravitational potentials. (a) Visible here are spoke-like accretion shocks (blue on top; yellow on b ...
... Figure 1. The gathering place. These six panels show density (top; red is less dense; yellow, denser) and temperature (bottom; red is 10 K; yellow, 1000 K) profiles of gas that falls into dark-matter gravitational potentials. (a) Visible here are spoke-like accretion shocks (blue on top; yellow on b ...
Supernovas Neutron Stars and Black Holes
... This object is about as large as our solar system, but weighs 1,200,000,000 times as much as our sun. This means that gravity is about one million times as strong as on the sun. Almost certainly this object is a black hole. ...
... This object is about as large as our solar system, but weighs 1,200,000,000 times as much as our sun. This means that gravity is about one million times as strong as on the sun. Almost certainly this object is a black hole. ...
The Formation of High Mass Stars
... What is the formation Mechanism: Gravitational collapse of an unstable turbulent cloud; Competitive Bondi-Hoyle accretion; Collisional Coalescence? ...
... What is the formation Mechanism: Gravitational collapse of an unstable turbulent cloud; Competitive Bondi-Hoyle accretion; Collisional Coalescence? ...
PH607 – Galaxies 1
... The course begins by considering the large-scale structure of our own Galaxy, the Milky Way. Components: Almost 90% of its mass cannot be accounted for (the "dark matter" problem). The Local Group: It then goes on to consider how the Milky Way fits in with what we see in other galaxies, and what the ...
... The course begins by considering the large-scale structure of our own Galaxy, the Milky Way. Components: Almost 90% of its mass cannot be accounted for (the "dark matter" problem). The Local Group: It then goes on to consider how the Milky Way fits in with what we see in other galaxies, and what the ...
The Bigger Picture
... Stellar parallax • Even the largest parallax (that for the nearest star) is small. The atmosphere blurs stellar images to about 1 arcsecond so `astrometrists’ are trying to measure a tiny motion of the centroid as it moves back and forth every six months. The lack of parallax apparent to the unaid ...
... Stellar parallax • Even the largest parallax (that for the nearest star) is small. The atmosphere blurs stellar images to about 1 arcsecond so `astrometrists’ are trying to measure a tiny motion of the centroid as it moves back and forth every six months. The lack of parallax apparent to the unaid ...
![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 horizontal branch, and then evolves more slowly to the right along this branch, as seen in Fig. 4.1. Horizontal branch evolution last only about 1% of the main-sequence lifetime. Once the helium in the core has been exhausted, the core (now composed mainly of oxygen and carbon) contracts again, ...
... the horizontal branch, and then evolves more slowly to the right along this branch, as seen in Fig. 4.1. Horizontal branch evolution last only about 1% of the main-sequence lifetime. Once the helium in the core has been exhausted, the core (now composed mainly of oxygen and carbon) contracts again, ...
Lecture9
... mass and the collapsed core will have mass larger than the neutron star maximum mass limit ~ 3M☉ So, if the remnant collapsed mass is larger than ~3M☉, the core keeps collapsing to singularity, and hence becomes a black hole. Note: Though nothing can come out of a black hole itself, the gas around t ...
... mass and the collapsed core will have mass larger than the neutron star maximum mass limit ~ 3M☉ So, if the remnant collapsed mass is larger than ~3M☉, the core keeps collapsing to singularity, and hence becomes a black hole. Note: Though nothing can come out of a black hole itself, the gas around t ...
White Dwarf Stars - Stellar Physics Department
... their spectral classification. This index is defined as θ = 50400/Teff . Therefore, a white dwarf showing Balmer lines with an effective temperature of 20 000 K will be classified DA2.5. The temperature index is not always provided. The temperature of white dwarfs ranges from ∼ 100 000 K down to abo ...
... their spectral classification. This index is defined as θ = 50400/Teff . Therefore, a white dwarf showing Balmer lines with an effective temperature of 20 000 K will be classified DA2.5. The temperature index is not always provided. The temperature of white dwarfs ranges from ∼ 100 000 K down to abo ...
Lecture 9
... We now need to assume something about the source of pressure in the star. We require an equation of state to relate the pressure to macroscopic properties of the gas (i.e. temperature and density) ...
... We now need to assume something about the source of pressure in the star. We require an equation of state to relate the pressure to macroscopic properties of the gas (i.e. temperature and density) ...
The Characteristics of Stars
... away. You may have noticed that luminous objects, such as flashlights and headlights, appear much brighter when they are closer to you than when they are farther away. This is because when the light source is farther away, the light spreads out over a larger area and becomes more diffuse. When the l ...
... away. You may have noticed that luminous objects, such as flashlights and headlights, appear much brighter when they are closer to you than when they are farther away. This is because when the light source is farther away, the light spreads out over a larger area and becomes more diffuse. When the l ...
Review 3 (11-18-10)
... •Young stars near clouds of gas and dust •Contraction and heating of clouds • Hydrogen fusion stops collapse II. Leaving the Main Sequence: Hydrogen fusion stops ...
... •Young stars near clouds of gas and dust •Contraction and heating of clouds • Hydrogen fusion stops collapse II. Leaving the Main Sequence: Hydrogen fusion stops ...
Lammer_final - University of Hertfordshire
... The team used computer models to study the possible atmospheric mass loss over a stellar lifecycle for exoplanets at orbiting distances of less than 0.06 AU where the planetary and stellar parameters are very well known from observations. The 49 planets considered in the study included hot gas giant ...
... The team used computer models to study the possible atmospheric mass loss over a stellar lifecycle for exoplanets at orbiting distances of less than 0.06 AU where the planetary and stellar parameters are very well known from observations. The 49 planets considered in the study included hot gas giant ...
Astro 204: Practice Questions Some of these questions are a bit
... 1. If a spherical planet has a constant density (ρ0 ) and is in hydrostatic equilibrium, one can straighforwardly find its pressure profile, and in particular its central pressure. (a) First, what is the relationship between its total mass (M ) and (total) radius (Rp )? (b) Derive its pressure−radiu ...
... 1. If a spherical planet has a constant density (ρ0 ) and is in hydrostatic equilibrium, one can straighforwardly find its pressure profile, and in particular its central pressure. (a) First, what is the relationship between its total mass (M ) and (total) radius (Rp )? (b) Derive its pressure−radiu ...
Stellar Temperature & Luminosity Student Page Purpose
... Use Wien’s Law to determine the temperature of a star, and the Luminosity-RadiusTemperature relation to determine a star’s luminosity. Before you Begin 1. If the peak in the black body curve of a star is at a longer wavelength than the peak wavelength for our Sun, how does the surface temperature of ...
... Use Wien’s Law to determine the temperature of a star, and the Luminosity-RadiusTemperature relation to determine a star’s luminosity. Before you Begin 1. If the peak in the black body curve of a star is at a longer wavelength than the peak wavelength for our Sun, how does the surface temperature of ...
Crux The Southern Cross
... There are many stars in the sky that when viewed through a telescope appear as two dots. It is common for two stars to be locked together gravitationally to form a binary star system. Sometimes double stars may only appear close together from our vantage point on earth. If in reality they do not int ...
... There are many stars in the sky that when viewed through a telescope appear as two dots. It is common for two stars to be locked together gravitationally to form a binary star system. Sometimes double stars may only appear close together from our vantage point on earth. If in reality they do not int ...
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.