Chapter 26
... where 90% of stars are found 4. Supergiants- very bright, very large stars 5. Giants- large and bright 6. White Dwarf- small, dense remains of low-medium mass stars, dimmer than the main sequence stars. ...
... where 90% of stars are found 4. Supergiants- very bright, very large stars 5. Giants- large and bright 6. White Dwarf- small, dense remains of low-medium mass stars, dimmer than the main sequence stars. ...
The Life Cycle of Stars
... When the hydrogen supply in the core begins to run out, and the star is no longer generating heat by nuclear fusion, the core becomes unstable and contracts. The outer shell of the star, which is still mostly hydrogen, starts to expand. As it expands, it cools and glows red. The star has now reached ...
... When the hydrogen supply in the core begins to run out, and the star is no longer generating heat by nuclear fusion, the core becomes unstable and contracts. The outer shell of the star, which is still mostly hydrogen, starts to expand. As it expands, it cools and glows red. The star has now reached ...
Life Cycle of a Star worksheet
... Learning Goal: I can describe the life cycle of various types of stars. All stars start as a ______________. A ______________ is a large cloud of gas and dust. Gravity can pull some of the gas and dust in a nebula together. The contracting cloud is then called a ___________. A protostar is the earli ...
... Learning Goal: I can describe the life cycle of various types of stars. All stars start as a ______________. A ______________ is a large cloud of gas and dust. Gravity can pull some of the gas and dust in a nebula together. The contracting cloud is then called a ___________. A protostar is the earli ...
Useful Things to Study (#2)
... Spectroscopic binaries, eclipsing binaries - what good are they? How does interstellar dust affect the light of stars along the line of sight? What fraction (by mass) of the interstellar medium is in gas and what fraction in dust? different components of the interstellar medium (cold atomic gas, eve ...
... Spectroscopic binaries, eclipsing binaries - what good are they? How does interstellar dust affect the light of stars along the line of sight? What fraction (by mass) of the interstellar medium is in gas and what fraction in dust? different components of the interstellar medium (cold atomic gas, eve ...
Solar Nebula Theory
... Basic properties of the Solar System that need to be explained: 1. All planets orbit the Sun in the same direction as the Sun’s rotation 2. All planetary orbits are confined to the same general plane 3. Terrestrial planets form near the Sun, Jovian planets further out ...
... Basic properties of the Solar System that need to be explained: 1. All planets orbit the Sun in the same direction as the Sun’s rotation 2. All planetary orbits are confined to the same general plane 3. Terrestrial planets form near the Sun, Jovian planets further out ...
Astronomy 20 Homework # 5 1.
... (a) Derive a formula for the b.h. luminosity as a function of its mass, assuming that its e ective area is 4RS2 , where RS is the Schwarzschild radius. (b) By setting L = c2 dM=dt, derive and solve the di erential equation for the evaporation time of a black hole with an initial mass of M0 . (c) E ...
... (a) Derive a formula for the b.h. luminosity as a function of its mass, assuming that its e ective area is 4RS2 , where RS is the Schwarzschild radius. (b) By setting L = c2 dM=dt, derive and solve the di erential equation for the evaporation time of a black hole with an initial mass of M0 . (c) E ...
Type II supernova
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times, the mass of the Sun (M☉) for this type of explosion. It is distinguished from other types of supernovae by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures, causing increasingly shorter stellar life spans. The degeneracy pressure of electrons and the energy generated by these fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with hydrogen and then helium, progressing up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel-iron core inert. Due to the lack of energy output allowing outward pressure, equilibrium is broken.When the mass of the inert core exceeds the Chandrasekhar limit of about 1.4 M☉, electron degeneracy alone is no longer sufficient to counter gravity and maintain stellar equilibrium. A cataclysmic implosion takes place within seconds, in which the outer core reaches an inward velocity of up to 23% of the speed of light and the inner core reaches temperatures of up to 100 billion kelvin. Neutrons and neutrinos are formed via reversed beta-decay, releasing about 1046 joules (100 foes) in a ten-second burst. The collapse is halted by neutron degeneracy, causing the implosion to rebound and bounce outward. The energy of this expanding shock wave is sufficient to accelerate the surrounding stellar material to escape velocity, forming a supernova explosion, while the shock wave and extremely high temperature and pressure briefly allow for theproduction of elements heavier than iron. Depending on initial size of the star, the remnants of the core form a neutron star or a black hole. Because of the underlying mechanism, the resulting nova is also described as a core-collapse supernova.There exist several categories of Type II supernova explosions, which are categorized based on the resulting light curve—a graph of luminosity versus time—following the explosion. Type II-L supernovae show a steady (linear) decline of the light curve following the explosion, whereas Type II-P display a period of slower decline (a plateau) in their light curve followed by a normal decay. Type Ib and Ic supernovae are a type of core-collapse supernova for a massive star that has shed its outer envelope of hydrogen and (for Type Ic) helium. As a result, they appear to be lacking in these elements.