Chapter 13 Practice Questions
... excess energy and therefore will not produce the additional gas pressure to halt the collapse. D) Iron nuclei are so large that they occupy all remaining space and so the collapse ...
... excess energy and therefore will not produce the additional gas pressure to halt the collapse. D) Iron nuclei are so large that they occupy all remaining space and so the collapse ...
transition
... photons and small pieces of slightly clumped matter. The Universe remains ionized as the electrons can not yet recombine with the protons to make neutral hydrogen. When the temperature cools to 3000K, recombination happens, the surface of last scattering is reached, and the radiation dominated era i ...
... photons and small pieces of slightly clumped matter. The Universe remains ionized as the electrons can not yet recombine with the protons to make neutral hydrogen. When the temperature cools to 3000K, recombination happens, the surface of last scattering is reached, and the radiation dominated era i ...
Appendix 2
... galaxies are formed must have come into existence as a single point – the “Big Bang” – approximately 15 billion (15,000,000,000) years ago. (There are other possibilities – but this is the standard model – which most cosmologists consider to be the best theory on present evidence.) From the theory o ...
... galaxies are formed must have come into existence as a single point – the “Big Bang” – approximately 15 billion (15,000,000,000) years ago. (There are other possibilities – but this is the standard model – which most cosmologists consider to be the best theory on present evidence.) From the theory o ...
Stellar Evolution
... Masses difficult to determine, but wide ranges observed in binary systems, from 5 – 77 M,, generally around 30 M, Apart from these guys, most other main sequence stars are very well behaved. They have a range of other characteristics based upon their masses. High mass stars (10 M, and up) o Con ...
... Masses difficult to determine, but wide ranges observed in binary systems, from 5 – 77 M,, generally around 30 M, Apart from these guys, most other main sequence stars are very well behaved. They have a range of other characteristics based upon their masses. High mass stars (10 M, and up) o Con ...
Globular Cluster Formation in CDM Cosmologies
... primordial gas contains hydrogen and helium. Start with a small, cold, dark matter halo – about a million times mass of the Sun. Gas within it cools down to 200 K, (molecular hydrogen is the coolant) A 100 solar mass core forms inside a filamentary “molecular cloud” ...
... primordial gas contains hydrogen and helium. Start with a small, cold, dark matter halo – about a million times mass of the Sun. Gas within it cools down to 200 K, (molecular hydrogen is the coolant) A 100 solar mass core forms inside a filamentary “molecular cloud” ...
Document
... first term in the bracket represents the creation of element i, while the second term gives the destruction of element i. Associated with each of these reactions is an energy (per unit mass), ϵij . If Qij is the amount of energy generated (or lost) when one particle of i reacts to form j, then ϵij = ...
... first term in the bracket represents the creation of element i, while the second term gives the destruction of element i. Associated with each of these reactions is an energy (per unit mass), ϵij . If Qij is the amount of energy generated (or lost) when one particle of i reacts to form j, then ϵij = ...
L and T Dwarfs - Indiana University
... Free-free opacities – Thomson and Rayleigh scattering In metal-poor low mass stars, pressure induced absorption of H2H2 is important in the IR (longer than 1 micron) H2 molecules have allowed transitions only at electric quadrupole and higher order moments, so H2 itself is not significant Also signi ...
... Free-free opacities – Thomson and Rayleigh scattering In metal-poor low mass stars, pressure induced absorption of H2H2 is important in the IR (longer than 1 micron) H2 molecules have allowed transitions only at electric quadrupole and higher order moments, so H2 itself is not significant Also signi ...
Scientific Justification
... clusters) to determine the age, it is crucial that we calibrate this cooling delay. Otherwise, we will underestimate the true ages. A typical white dwarf with a mass of 0.6 M¯ will begin to crystallize when it reaches Teff ∼ 6000-8000 K, depending on the core composition. More massive white dwarfs h ...
... clusters) to determine the age, it is crucial that we calibrate this cooling delay. Otherwise, we will underestimate the true ages. A typical white dwarf with a mass of 0.6 M¯ will begin to crystallize when it reaches Teff ∼ 6000-8000 K, depending on the core composition. More massive white dwarfs h ...
7/3 Some stars were found in regions above the main sequence
... We look at luminosity classes — due to the fact that there are subtle differences between the main sequence spectra and spectra from giant stars. Giant stars, while much larger than main sequence stars, are no more massive. They are much less dense, and the effect of the low density on the spectrum ...
... We look at luminosity classes — due to the fact that there are subtle differences between the main sequence spectra and spectra from giant stars. Giant stars, while much larger than main sequence stars, are no more massive. They are much less dense, and the effect of the low density on the spectrum ...
Stellar evolution, II
... What would happen to the orbit of the Earth if the Sun somehow became a black hole? a.The Earth’s orbit would be unchanged. b.The Earth would sucked into the black hole. c.The Earth would be ejected from the solar system. d.We have no idea. ...
... What would happen to the orbit of the Earth if the Sun somehow became a black hole? a.The Earth’s orbit would be unchanged. b.The Earth would sucked into the black hole. c.The Earth would be ejected from the solar system. d.We have no idea. ...
RachelStarProject
... different paths at the end of their lives because high-mass stars become so compact that they have to do something different than low-mass stars. ...
... different paths at the end of their lives because high-mass stars become so compact that they have to do something different than low-mass stars. ...
Nuclear Astrophysics (a Cosmic Cookbook)
... • In binary systems, one star can evolve to a compact white dwarf while the other can become a red giant • hydrogen-rich material is transferred (or accreted ) onto the white dwarf surface • the temperature and density get so high that hydrogen starts to fuse with carbon, nitrogen, oxygen and heavie ...
... • In binary systems, one star can evolve to a compact white dwarf while the other can become a red giant • hydrogen-rich material is transferred (or accreted ) onto the white dwarf surface • the temperature and density get so high that hydrogen starts to fuse with carbon, nitrogen, oxygen and heavie ...
Grade 9 Science EXAM REVIEW – ASTRONOMY
... Therefore Neptune is 30.02 AU from the Sun. 11. Define each of the following terms: asteroid = a rocky object smaller than a planet that orbits a star comet = small, irregularly shaped bodies that are made primarily of gas and ice meteor = a small body of matter from outer space that comes into the ...
... Therefore Neptune is 30.02 AU from the Sun. 11. Define each of the following terms: asteroid = a rocky object smaller than a planet that orbits a star comet = small, irregularly shaped bodies that are made primarily of gas and ice meteor = a small body of matter from outer space that comes into the ...
PoA Examples Sheet 3
... 7. A source of ionising radiation is located at a distance R from a star surrounded by a neutral protoplanetary disc. A neutral disc wind feeds gas into an ionisation front which cuts the line between the star and the ionising source at at a distance rI from the star. Explain why (in the limit R >> ...
... 7. A source of ionising radiation is located at a distance R from a star surrounded by a neutral protoplanetary disc. A neutral disc wind feeds gas into an ionisation front which cuts the line between the star and the ionising source at at a distance rI from the star. Explain why (in the limit R >> ...
Variable Stars
... Dwarf stars- less luminous, red, orange or yellow White dwarf- very faint, small and dense Variable Stars- vary in brightness over regular periods or cycles ...
... Dwarf stars- less luminous, red, orange or yellow White dwarf- very faint, small and dense Variable Stars- vary in brightness over regular periods or cycles ...
Life and Death of a Star
... • Compare and Contrast the Life of a Star to the Life of a Human. Mention the Growth, Stages of Development, Life Expectancy, and Death of Each. • Compare and Contrast the Formation, Life, Destruction and Recycling of Veterans Stadium to a Solar System • Compare and Contrast the Big Bang to a Bag of ...
... • Compare and Contrast the Life of a Star to the Life of a Human. Mention the Growth, Stages of Development, Life Expectancy, and Death of Each. • Compare and Contrast the Formation, Life, Destruction and Recycling of Veterans Stadium to a Solar System • Compare and Contrast the Big Bang to a Bag of ...
The Virial Theorem
... The Virial Theorem • A fundamental equa-on necessary for proper understanding of stellar forma-on is the virial theorem. • The virial theorem gives the rela-on between the poten-al and kine-c energies of ...
... The Virial Theorem • A fundamental equa-on necessary for proper understanding of stellar forma-on is the virial theorem. • The virial theorem gives the rela-on between the poten-al and kine-c energies of ...
Finding the North Star - Science
... Throughout the night, stars appear to travel across the sky in circular arcs. This apparent motion is caused by the Earth spinning on its axis. Stars that appear close to the North Star travel in small circles. Stars that appear far from the North Pole travel in wide circles. Because the North Star ...
... Throughout the night, stars appear to travel across the sky in circular arcs. This apparent motion is caused by the Earth spinning on its axis. Stars that appear close to the North Star travel in small circles. Stars that appear far from the North Pole travel in wide circles. Because the North Star ...
Stellar Kinematics
... “Stars” that are not massive enough to have hydrogen fusion in their cores Mass < 0.08 MSun (84 MJupiter) ...
... “Stars” that are not massive enough to have hydrogen fusion in their cores Mass < 0.08 MSun (84 MJupiter) ...
insert - Athens
... Stars are glowing, rotating balls of gas. Even though you may see thousands of stars, you are only seeing a small fraction of the stars in our universe. Scientists estimate that there are more than a thousand billion billion stars in our universe! However, almost all of them are too far away for you ...
... Stars are glowing, rotating balls of gas. Even though you may see thousands of stars, you are only seeing a small fraction of the stars in our universe. Scientists estimate that there are more than a thousand billion billion stars in our universe! However, almost all of them are too far away for you ...
printer-friendly sample test questions
... 12. The red and yellow line (also indicated by an arrow) on the diagram below shows a how a single star is changing with time. Note that the star is about the same mass as our Sun. ...
... 12. The red and yellow line (also indicated by an arrow) on the diagram below shows a how a single star is changing with time. Note that the star is about the same mass as our Sun. ...
paper size (650 Kbtyes)
... 8 Draw a line from Arcturus to Vega. One-third of the way sits "The Northern Crown." Two-thirds of the ...
... 8 Draw a line from Arcturus to Vega. One-third of the way sits "The Northern Crown." Two-thirds of the ...
Lecture 7 Evolution of Massive Stars on the Main Sequence and
... In fact, except for a thin region near their surfaces, such stars will be entirely convective and will have a total binding energy that approaches zero as approaches zero. But the calculation applies to those surface layers which must stay bound. Completely convective stars with a luminosity propo ...
... In fact, except for a thin region near their surfaces, such stars will be entirely convective and will have a total binding energy that approaches zero as approaches zero. But the calculation applies to those surface layers which must stay bound. Completely convective stars with a luminosity propo ...
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.