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The Life History of Stars – High Mass

The Life History of Stars – High Mass. Mommy. Fetus. Adult. Old Man. Heart Attack. Corpse. Outline. Molecular Cloud Protostar Main Sequence Supergiant Stages Massive Star Supernova Neutron Star or Black Hole. Supergiant Stages. Molecular Cloud Protostar Main Sequence

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The Life History of Stars – High Mass

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  1. The Life History of Stars – High Mass Mommy Fetus Adult Old Man Heart Attack Corpse Outline • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole

  2. Supergiant Stages • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole Variety of fuels burned in massive stars: • Main Sequence: Hydrogen  Helium • CHB/DSB: Helium  Carbon/Oxygen • More stages: • Carbon  Neon • Neon  Silicon, Oxygen • Oxygen  Silicon • Silicon  Iron • Each stage produces less energy than the last • Each stage goes faster than the last

  3. Supergiant Stages Supergiant Stages • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole Hydrogen Helium Carbon/Oxygen Neon Silicon Iron

  4. Stages Go Steadily Faster – 25 MSunstar Late Stages • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole StageFuelTime Main Sequence Hydrogen 7 Myr CHB/DSB Helium 700 kyr Carbon 600 yr Neon 1 yr Oxygen 6 months Silicon Supergiant Stages Q. 80: Extrapolating the Length of Stages

  5. Stages Go Steadily Faster – 25 MSunstar Late Stages • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole StageFuelTime Main Sequence Hydrogen 7 Myr CHB/DSB Helium 700 kyr Carbon 600 yr Neon 1 yr Oxygen 6 months Silicon 1 day (Collapse) Iron (?) 1 second Supergiant Stages • Iron can’t burn – it is completely “burned” • When it hits the Chandrasekhar limit, it will collapse under its own weight

  6. Core Collapse • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole • Iron Core begins to collapse • Iron disintegrates • P n5/3/m • Electron degeneracy pressure enormous • Will do anything to get rid of electrons • Electron + proton  neutron + neutrino • Electrons (and protons) disappear • Pure neutrons + +

  7. Core Bounce • Eventually, the neutron’sdegeneracy pressure kicks in • Core slams to a stop in 1millisecond • Rings like a bell • Temperature soars 1 trillion K • Over next 10 seconds, energypours out in the form of(invisible) neutrinos • More than rest of Universe! • Shock wave expands outwards and destroys star P n5/3/m Q. 81: Neutron Degeneracy Pressure

  8. Massive Star Supernova Protons, Neutrons, Electrons • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole Iron Core Neutron Star Core Bounce Shock Waves

  9. Massive Star Supernova • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole Supergiant Stages Hydrogen Helium Carbon/Oxygen Neon Silicon Iron

  10. After the Supernova • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole • Expanding shock wave slams through the rest of the star • Takes several hours • Every other element is produced • Most of the mass of the star – including many heavy elements – get recycled back into the Universe – a Supernova Remnant • The Earth is made of star stuff • The ball of neutrons – a neutron star – remains at the center

  11. Supernovae SN1994 D

  12. Supernova 1987a SN1987A

  13. Supernova Remnant – Crab Nebula

  14. Supernova Remnant – Crab Nebula

  15. Supernova Remnant – Crab Nebula Near Ultraviolet Far Ultraviolet Visible X-Rays

  16. Tycho’s Supernova Remnant X-Rays X-Rays Plus Infrared

  17. Supernova Remnants Veil Nebula Puppis A

  18. Supernova Remnants N49 W49B Kepler SNR

  19. Supernova Remnants Tarantula Nebula

  20. Supernova Remnants – Vela Nebula

  21. Supernova Remnants – DEM L316

  22. Neutron Stars 20 • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole • Structure • Pure neutrons • Held up by neutron degeneracy pressure • Mass • Most around 1.4 MSun • Maximum mass2 – 3 MSun • Size • Typically 25 km • More massive smaller 15 10 5 0

  23. Neutron Stars • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole

  24. Pulsars • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star or Black Hole • Most stars spin • Shrinking core spins faster • Magnetic fields, trapped, get concentrated • Whirling strong magnet • Charged particles get whipped around by magnet - they radiate • Lighthouse effect Q. 82: Pulsars

  25. Pulsars Crab Pulsar Optical and X-ray

  26. Forming a Black Hole Very massive stars (>30 MSun) • Core gets too heavy and collapses to neutron star • Outer layers not completely blownaway – they fall back towards the star • Mass exceeds maximum mass • Gravity exceeds pressure • Star collapses again • Once it reaches its event horizon, nothing can stop it • It becomes a black hole • Infinite density • Molecular Cloud • Protostar • Main Sequence • Supergiant Stages • Massive Star Supernova • Neutron Star orBlack Hole

  27. Einstein’s Theories of Relativity Singularity • Special theory of relativity • Says nothing can go faster than light • General theory of relativity • Describes gravity • Using Newton: escape velocity: • You can’t escape when ve = c • You can’t escape if youare closer than: • The event horizon Help! Event Horizon

  28. Gamma Ray Bursters • There are intense bursts of gamma rays • Typically last about 30 seconds • Brighter than a supernova • Followed by “fireball” of visible light • Followed by a massive star supernova explosion • Cause is probably very massive star death and creation of black hole • They occur in galaxies • Typically, galaxies have lots of young stars in them

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