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PCS 181
Margaret Buckby

Astronomy Notes Chapter 2Birth of StarsLives of StarsInterstellar This is gas and dust that occupy space between the stars Stars form out of the gasdust in space Clouds are lightyears acrossWhen a star is born there is a high wind that blows off particles and then the star can then appear DustDust is approx 1 of the total visible mass is space Obscures our view of distant objects in the galaxy What is the dust It is a mixture of Elongated tiny grains of dirty ice Grains of graphite carbon Silicate particles comes right under carbon in periodic table therefore it has the same chemical properties as carbon Complex molecules Interstellar Reddening Light from a star passes through the dust cloud The dust particles are approx the same length as blue wavelengths The dust scatters blue wavelengths more than red wavelengths Red wavelengths go right through the dust particles but the blue wavelengths have trouble and is therefore scattered A larger number of red photons pass unhindered through the dust and reach the observer Star appears redder than it actually is Gas There is approx 100 times more gas mass than dust mass in the universe GasDust is approx 100 We can only detect 4 of the universe The visible universe contains Test Question 75 hydrogen 24 helium 1 other H1 RegionsThese are clouds of neutral NOT ionized Hydrogen There are the same number of protons as electronsAtom is ionized if you take one or more electronsContains approx 1 Mo to approx 100 MoThe cold hydrogen gas is in its ground state n1 orbit It is in its first permitted orbit Protons and the electron are either spinning together or opposite from each other This spinning gives us an indication of The hydrogen atom has TWO possible ground state configurations Parallel spin or aligned spin same direction which takes more energy When it changes direction it is known as a spin flipWhen it performs a spin flip that excess energy must give off its radiation as a burst of energy The electron can undergo a spontaneous spin flip from the aligned parallel state to the opposed antiparallel state
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