Exam 3 Created by Gregory Galmin Properties of Stars Remember the idea of parallax you can see the stars moving relative to one another Using parallax to see how far stars are away from you Different times of the year the stars look different relative to the background stars The parallax is the angle measured in arc seconds 1 arc second from December to June the object is 3 26 light years away 2 arc seconds half a parsec Alpha Centauri is the closest star The smaller the parallax the further away it is Aristotle introduced parallax We cannot measure millions of light years away we don t have the resolution Today we see the parallax because we have telescopes accurate measurements Brightness of stars tells us something about the size of the star Hot solid liquid or gas light passes through the prism you will always get a rainbow spectrum If the light goes through some cloud of cool gas you get absorption lines because the light is absorbed The absorption bands are like nodes on a guitar string it will only show particular nodes for different matter Every element has a fingerprint an emission and absorption spectrum Hydrogen has a red line and a green line Think of the electron as a cloud of charge There is no way to be between stairs Each excitation requires a certain amount of energy E hf h is Planck s constant and f is the frequency This is the basis of quantum theory The size of an atom is in the scale of a billionth of a meter Absorption spectrum and emission spectrum are complimentary You can only throw up something you ate We can tell by Doppler effect which way the star is rotating The spectrum of a slowly rotating star is different that the spectrum of a rapidly rotating star Hertzsprung Russell diagram Color and brightness of a star statistical plot age is related to wrinkles You make a few assumptions of stars Stars go through an evolution This star is like that star so you can assume similar things about them Types of stars Main sequence white dwarfs giants supergiants White dwarf white or bluish star but not as luminous as the sun a dead star Blue is hotter than Red Giants are sick but not dead Main sequence stars live billions of years Giants and super giants may live millions of years Stars are dying and being born RIGHT NOW
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