Low Mass Stars: Crash Course Astronomy #29
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Today we are talking about the life -- and death -- of stars. Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon (and also some oxygen and neon). When this happens they expand, get brighter, and cool off, becoming red giants. They lose most of their mass, exposing their cores, and then cool off over many billions of years. Crash Course Astronomy posters now available at DFTBA: http://store.dftba.com/products/crashcourse-astronomy-poster -- Table of Contents Low Mass Stars Live a Long Time 0:57 Larger Stars (Like Our Sun) Live Shorter Lives 3:10 Fueled By Fusion 3:58 How They Turn Into Red Giants 5:45 -- PBS Digital Studios: http://youtube.com/pbsdigitalstudios Follow Phil on Twitter: https://twitter.com/badastronomer Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashCourse Twitter - http://www.twitter.com/TheCrashCourse Tumblr - http://thecrashcourse.tumblr.com Support CrashCourse on Patreon: http://www.patreon.com/crashcourse -- PHOTOS/VIDEOS Stars http://skycenter.arizona.edu/sites/skycenter.arizona.edu/files/n6522_32in.jpg [credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona] The Sizes of Stars http://www.eso.org/public/usa/images/eso1030c/ [credit: ESO/M. Kornmesser] Fusion in the Sun https://commons.wikimedia.org/wiki/File:FusionintheSun.svg [credit: Borb, Wikimedia Commons] Mega Flares http://scitechdaily.com/images/Swift-Mission-Observes-Mega-Flares-from-a-Mini-Star.jpg [credit: NASA’s Goddard Space Flight Center/S. Wiessinger] Proxima Centauri https://www.spacetelescope.org/images/potw1343a/ [credit: ESA/Hubble & NASA] Physics in the Core http://solarscience.msfc.nasa.gov/images/cutaway.jpg [credit: NASA / Marshall Space Flight Center] Three Years of SDO Images http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11255 [credit: NASA's Goddard Space Flight Center/SDO] Sun & Red Giants http://kepler.nasa.gov/files/mws/kasc3.jpg [credit: NASA] Sun as Red Giant https://commons.wikimedia.org/wiki/File:Sun_red_giant.svg [credit:Oona Räisänen, Wikimedia Commons] Gone with the Wind https://www.eso.org/public/usa/images/wr124/ [credit: ESO] Expanding & cooling https://www.cfa.harvard.edu/sites/www.cfa.harvard.edu/files/images/pr/2009-23/1/base.jpg [credit: ESO/L. Calçada] Looking down a barrel of gas at a doomed star http://hubblesite.org/newscenter/archive/releases/1999/01/image/a/ [credit: The Hubble Heritage Team (AURA/STScI/NASA)] Expanding star orbit http://www.nasa.gov/centers/goddard/images/content/415775main_earthlike-exoplanet-full.jpg [credit: SO/L. Calçada] Red Giant Earth https://commons.wikimedia.org/wiki/File:Red_Giant_Earth.jpg [credit: Fsgregs, Wikimedia Commons] Crab Nebula https://en.wikipedia.org/wiki/Crab_Nebula#/media/File:Crab_Nebula.jpg [credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)]
Comments
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WHY DOESNT THIS HAVE MORE VIEWS ITS ABOUT SPACE
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gas, grass or mass
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Wait if our star is middle aged. What happens when is has a mid life crisis?
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can a low mass star be a G spectral class or can it only be K and M?
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hearing billion so many times takes the bang out of it, everything seems proximal, maybe everything should be expressed in thousands
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so in red dwarfs, the hydrogen and helium go out an come in (only the hydrogen) in a cycle?
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we can live near earth core for heat
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I just noticed that in the third part of the intro, everything is sucked into a cube
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Does forever last forever? Or does forever end, not lasting forever. Does forever not last forever then, so forever doesn't exist because forever cant last forever... forever.
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Looks like there's 45 high mass stars that didn't like the video.
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This is my favorite ceres get it?
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Does anyone know if that cute little Hank robot at 9:12 has a name? Thanks. :3
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The Sun is not 5 billion years old. The world hasn't even existed for that long. The world was created by God only about six and a half thousand years ago.
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Two major mistakes made. 1. Its when stars have too much Iron, not Carbon, is when fusion starts to cease.
2. We don't have 11 billion more years. We have 1 billion years, tops. By this time the sun's output and luminosity would have increased enough to boil away Earth's oceans, and without water, we're screwed. -
Forget Solar expansion, we should worry about climate change.
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Bye bye earth it will get eatin by the red sun in 6 billion years
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I don't understand why people get upset when they learn that in five billion years, the Earth will be destroyed by the Sun. I'll be dead then, you'll be dead then, your great-grandchildren's great-grandchildren will be dead then. Who cares? Not trying to be mean, you can be upset if you want, it just doesn't make sense to me.
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...when it is not hot enough to fuse carbons.... this is the part that i dont quite get it....
why doesnt it just shrink to become a white dwarf without a violence?
why does it still have to blow up the outer layer? can you call this act a small super nova? i know that the sun is not even a candidate for type 1a supernova.
you said the Helium core fusion is hot enough to influence the Hydrogens at outer layer to nuclear-fuse. i need more explaination here. outer layer density i think is not densed enough for quantum tunnelings, so the outer layer of a star needs the real Hydrogen fusing temperature, which is about 10 billion degrees, and there is no way that self-total gravitational potential energy bound Helium core fusion can provide it.
and how can the weak interaction at outer layer be high enough? -
This is probably one of the best explanations to what happens to a star that I have ever heard!
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Hello Phil,
It might be nice if you also showed how the track on the HR diagram looks like. :)
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