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Stellar Evolution: From Protostar to Black Hole

Explore the fascinating journey of a star from its protostar phase to a black hole, including main sequence, red giant, white dwarf, and more. Learn about stellar evolution and the energy sources that power these celestial bodies. Follow the lifecycle of stars through Hubble images and scientific illustrations, and delve into topics like nuclear fusion and the formation of brown dwarfs. This comprehensive guide offers a glimpse into the cosmic wonders of our universe.

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Stellar Evolution: From Protostar to Black Hole

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  1. M<0.08 .08<M<0.4 0.4<M<1.4 1.4<M<~4 M>~4 P R O T O S T A R | M a i n S e q u e n c e | R E D G I A N T | | | Planetary Supernova | | | Nebula | | W h i t e D w a r f | B r o w n D w a rf Neutron Star OR Black Hole Stellar Evolution M A I N S E Q U E N C E R E D G I A N T W H I T E D W A R F B R O W N D W A R F

  2. Hubble image of gas and dust around a cluster of young, hot stars Fig. 12-1, p.248

  3. Protostar – contracting gas due to gravity. Size ~ 1 ly ~ 1013 km, energy source -- gravity. Main Sequence – normal star. Size ~ 106 km to 107 km, Energy – nuclear fusion 4H  He + energy. 0.7% of mass converted to energy, E = mc². Next stage – red giant. Size 100 times Main Sequence. If not enough mass then Brown Dwarf. Stellar Evolution

  4. Fig. 12-2a, p.248

  5. Main sequence stars Protostar Fig. 12-2b, p.248

  6. Fig. 12-4, p.250

  7. HST Protostar with two jets Fig. 12-5a, p.251

  8. Protostar with Jet Jet Fig. 12-5b, p.251

  9. Protostar with two jets Fig. 12-5c, p.251

  10. Mass of He is Less than 4 H. Difference gets Converted to Energy E = mc². Fig. 12-6, p.252

  11. Fig. 12-8, p.253

  12. Proton - proton chain fusion in main Sequence stars. Fig. 12-10, p.255

  13. Main Sequence stars. • The star is very stable and continues to produce energy until the • hydrogen in the core gets depleted and hydrogen to helium • fusion stops. • Energy source – Fusion of 4HHe + Energy • The energy production is directly proportional to ~ the mass to the • power 4 (M4). • Since the supply of energy is proportional to the mass, • then the lifetime of the star in the main sequence mode is • proportional to M/M4 = 1/M³. • The lifetime of a one solar mass star is 10 billion years (1010 yrs). • Other main sequence star lifetime in main is 1010/M³ years, • where M is in units of solar mass. • Since massive stars live a shorter lifetime, it is not surprising that • most of the main sequence star are low mass ones.

  14. Hydrostatic equilibrium in a main sequence star.

  15. Brown dwarf Brown dwarf Fig. 12-11b, p.256

  16. ν hardly interacts, so it escapes and reaches Earth with the velocity of light or in about 8 minutes. Since ν hardly interacts, ν detectors need to be extremely large. Solar neutrino problem pre 2000 – there are not enough neutrinos to account for the energy of the Sun. Problem solved, ν has a very small mass. Solar Neutrinos (ν)

  17. Homestake Solar neutrino Telescope South Dakota Fig. 12-12, p.256

  18. Water detector for Neutrinos in Japan. Kamiokande Fig. 12-13, p.257

  19. Sudbury Neutrino Observatory in Canada. Fig. 12-14, p.258

  20. Note: Planetary nebula are NOT related to planets. Fig. 12-15, p.258

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