PowerPoint PresentationANNOUNCEMENTS 11/09/11Short visual review of evolution - sun-like starSlide 4Learning Goals:Closer look at stars in Orion:Slide 7How bright will Betelgeuse be when it goes supernova?Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Changes in temperature and luminosity for massive starsSlide 17Mass > 10 solar massesFusion to iron marks certain doomSlide 20Slide 21What happens to the star?Slide 23Slide 24Summary of the evolution of a high-mass starSlide 261QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.2ANNOUNCEMENTS 11/09/11ANNOUNCEMENTS 11/09/11 C.L.U.E. Thursday evening 11/10/11 There WILL be a question about massive star evolution, and we will answer it today in lecture. Survey still open for your indicating the topics you are most unsure of for Monday’s exam 3. You do have a textbook, and for most of your uncertainties with the various topics, reading the text will help!3Short visual review of evolution - sun-like starShort visual review of evolution - sun-like starDeath sequence of the SunUnderstanding stages of low-mass star deathQuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.Radius of the star turning into a red giant is increasing due to the great increase in luminosity being provided by the fusion occurring in a shell around the core.Radius of the star turning into a red giant is increasing due to the great increase in luminosity being provided by the fusion occurring in a shell around the core.4Evolution of StarsEvolution of StarsPart II – MASSIVE STARSPart II – MASSIVE STARS5Learning Goals:Learning Goals: Explain why the much higher mass of some stars causes their evolution to be so different from the Sun.Outline the basic stages of the evolution of a massive star6Closer look at Closer look at stars in Orion:stars in Orion:QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.7Betelgeuse~20 x solar massCan actually SEE this star’s surface!8QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.How bright will Betelgeuse be when it goes How bright will Betelgeuse be when it goes supernova?supernova?€ m − M = 5log(d) − 5m = M + 5log(d) − 5msn= −15 + log10.005( )− 5msn= −15 + log(200) − 5msn≈ −17€ mfull −moon≈ −13910Eta Carinae100+ times as massive as the Sun.It is so massive that it can barely hold itself together. Some astronomers think Eta Carinae might die in a supernova blast within our lifetime. http://www.spitzer.caltech.edu/Media/releases/ssc2005-12/ssc2005-12a.shtml1112Some perspectiveCNO cycle1314 No helium flash. Helium carbon fusion starts when temperature gets high enough (~100,000,000 K) Core does NOT become degenerate Rest of star expandsEvolution for a star > 10 times Sun’s massEvolution for a star > 10 times Sun’s massQuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.Triple-alpha fusion of He to C needs extremely high T’s to operate.15 Core shrinks, heats Carbon oxygen fusion starts when temperature high enough Fusion continues to heavier and heavier nuclei QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.16Changes in temperature and luminosity for massive starsChanges in temperature and luminosity for massive stars1718Mass > 10 solar massesMass > 10 solar masses19Fusion to iron marks certain doomFusion to iron marks certain doom202122What happens to the star?What happens to the star?23QuickTime™ and a decompressorare needed to see this picture.2425Summary of the evolution of a high-mass starSummary of the evolution of a high-mass star26 Explain why the much higher mass of some stars causes their evolution to be so different from the Sun.Outline the basic stages of the evolution of a massive
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