A1 19 Star Death

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Miller's Astronomy 1 lecture notes on Star Death

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A1 19 Star Death

  1. 1. High Mass and Binary System Stellar Evolution LACC §: 22.1, 22.2, 23.5 • High Mass (>~10 Msolar) Stars • Binary Systems • Enrichment of the ISM An attempt to answer the “big questions”: What is out there? Where did I come from? Thursday, April 29, 2010 1
  2. 2. HR Diagram http://outreach.atnf.csiro.au/education/senior/astrophysics/stellarevolution_hrintro.html Thursday, April 29, 2010 2
  3. 3. Low and High Mass Evolution The stellar wind causes mass loss for AGB stars. This loss is around 10-4 solar masses per year, which means that in 10,000 years the typical star will dissolve, leaving the central, hot core (the central star in a planetary nebula). http://abyss.uoregon.edu/~js/ast122/lectures/lec16.html Thursday, April 29, 2010 3
  4. 4. High Mass Evolution If the star is larger than 8 solar masses, then the core continues to heat. Carbon and Text oxygen fuse to form neon, then magnesium, then silicon. All forming into burning shells surrounding an iron ash core. http://abyss.uoregon.edu/~js/ast122/lectures/lec16.html Thursday, April 29, 2010 4
  5. 5. Type-II Supernova http://www.williams.edu/ astronomy/Course-Pages/111/ Images/SN/sn_explosion.gif Thursday, April 29, 2010 5
  6. 6. Supernova 1987a http://cse.ssl.berkeley.edu/bmendez/ay10/2000/cycle/snII.html Thursday, April 29, 2010 6
  7. 7. Type-II Supernova http://ircamera.as.arizona.edu/NatSci102/NatSci102/movies/suprnova.mpg Thursday, April 29, 2010 7
  8. 8. Supernova Light Curves http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/supernovae.htm Thursday, April 29, 2010 8
  9. 9. Supernova 1987a http://www.stsci.edu/~mutchler/ http://apod.nasa.gov/apod/ images/clouds_ctio.jpg ap020331.html Thursday, April 29, 2010 9
  10. 10. Supernova 1987a http://www.sflorg.com/spacenews/sn022207_02.html Thursday, April 29, 2010 10
  11. 11. Novae and Type-Ia Supernovae http://antwrp.gsfc.nasa.gov/apod/ap060726.html Thursday, April 29, 2010 11
  12. 12. Novae and Type-Ia Supernovae Spectacular explosions keep occurring in the binary star system named RS Ophiuchi. Every 20 years or so, the red giant star dumps enough hydrogen gas onto its companion white dwarf star to set off a brilliant thermonuclear explosion on the white dwarf's surface. At about 2,000 light years distant, the resulting nova explosions cause the RS Oph system to brighten up by a huge factor and become visible to the unaided eye. The red giant star is depicted on the right...while the white dwarf is at the center of the bright accretion disk on the left. As the stars orbit each other, a stream of gas moves from the giant star to the white dwarf. Astronomers speculate that at some time in the next 100,000 years, enough matter will have accumulated on the white dwarf to push it over the Chandrasekhar Limit, causing a much more powerful and final explosion known as a supernova. http://antwrp.gsfc.nasa.gov/apod/ap060726.html Thursday, April 29, 2010 12
  13. 13. Type Ia and Type II Supernovae http://www.ifa.hawaii.edu/~barnes/ast110_06/tooe/1314a.jpg Thursday, April 29, 2010 13
  14. 14. Type-I vs. Type-II Supernovae http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap21/FG21_08.jpg Thursday, April 29, 2010 14
  15. 15. Stellar Evolution: [Nova] Low vs. High Mass http:// www.redorbit.com/ education/ reference_library/ universe/ stellar_evolution/246/ index.html Thursday, April 29, 2010 15
  16. 16. Enrichment of the ISM when the stellar core becomes solid iron, there is no fusion reaction available to produce energy to keep the core hot and maintain the pressure that resists gravity the iron core collapses in just a few seconds to a neutron star (or black hole). http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/supernovae.htm Thursday, April 29, 2010 16
  17. 17. Enrichment of the Interstellar Medium Gas is recycled in the Galaxy. It goes into forming stars and is returned during the death throws of stars enriched with heavy elements for the next generation of stars. It is a giant cycle of life. http://cse.ssl.berkeley.edu/bmendez/ay10/2002/notes/lec16.html Thursday, April 29, 2010 17
  18. 18. High Mass and Binary System Stellar Evolution LACC §: 22.1, 22.2, 23.5 • High Mass (>~10 Msolar) Stars: fuse all the way up to Fe, iron; Type-II Supernovae (sometimes Gamma-Ray Bursters) fuse past Fe, iron • Binary Systems: Novae, Type-Ia Supernovae, X-ray Binaries, X-ray Bursters) • Enrichment of the ISM: Stars convert H into elements up to Fe: He, C, O, Ne, Mg, Si, Fe; Supernovae create elements heavier than Fe An attempt to answer the “big questions”: What is out there? Where did I come from? Thursday, April 29, 2010 18
  19. 19. LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed. • Ch. 22, pp. 509-511: 8 (Specifically, what is the cause of each: Nova, Type Ia Supernova, Type II Supernova) Due first class period of the next week (unless there is a test this week, in which case it’s due before the test). AstroTeams, be working on your Distance Ladders Thursday, April 29, 2010 19
  20. 20. Stellar Remnants LACC §: 22.1, 22.2, 23.5 • White Dwarfs • Neutron • Black Holes An attempt to answer the “big questions”: What is out there? Where did I come from? Thursday, April 29, 2010 20
  21. 21. Stellar Remnants neutron degeneracy electron degeneracy pressure pressure http://www.maa.mhn.de/Scholar/Starlife/evolutnc.html Thursday, April 29, 2010 21
  22. 22. White Dwarf: Mass-Radius Relationship About 15 km About 10,000 km http://ircamera.as.arizona.edu/NatSci102/lectures/whitedwrf.htm Thursday, April 29, 2010 22
  23. 23. Stellar Remnants Density: ~0.5 tons/cc About 15 km About 10,000 km Density: ~100,000,000 tons/cc http://astro.ucc.ie/research/intro/index.html Thursday, April 29, 2010 23
  24. 24. Stellar Remnants: Black Hole Note that the Schwarzschild radius scales with the mass of the black hole. The Schwarzschild radius of a 1 solar mass black hole is 3 x 105 cm [3 km, less than 2 miles]. http://www.astro.cornell.edu/academics/courses/astro201/bh_structure.htm Thursday, April 29, 2010 24
  25. 25. Neutron Stars / Pulsars What a star becomes when it dies depends on the mass left when all possible nuclear fuels are exhausted and the star has lost some of its original mass by ejecting it: M <= 1.4 M -----> white dwarf (planetary nebulae) 1.4 M <M < ~3 M --> neutron stars/pulsars (type II supernova) M > ~ 3 M ----> supernovae/black holes (type II supernova) Pulsar Animation http://ircamera.as.arizona.edu/NatSci102/lectures/whitedwrf.htm Thursday, April 29, 2010 25
  26. 26. The Crab Nebula/ Pulsars http://hera.ph1.uni-koeln.de/ %7Eheintzma/NS1/SN1054.htm This picture shows a time sequence for the pulsar in the Crab nebula, shown in context against an image.... Both the nebula and its central pulsar were created by a supernova explosion in the year 1054 A.D. The enlarged region is a mosaic of 33 time slices, ordered from top to bottom and from left to right. Each slice represents approximately one millisecond in the period of the pulsar. Thursday, April 29, 2010 26
  27. 27. What would a naked black hole look like? Maybe... “A (simulated) Black Hole of ten solar masses as seen from a distance of 600 km with the Milky Way in the background (horizontal camera opening angle: 90°).” http://www.tutorgig.com/ed/black_hole Thursday, April 29, 2010 27
  28. 28. http://www.spitzer.caltech.edu/Media/happenings/20050526/ Thursday, April 29, 2010 28
  29. 29. Gamma-Ray Bursts James Annis, an astrophysicist at Fermilab, near Chicago, has speculated that such events could sterilize entire galaxies, wiping out life-forms before they had the chance to evolve to the stage of interstellar travel. 1 "If one went off in the Galactic center," he wrote, "we here two-thirds of the way out of the Galactic disk would be exposed over a few seconds to a wave of powerful gamma rays." It would be enough, according to Annis, to exterminate every species on Earth. Even the hemisphere shielded by the planet's mass from immediate exposure would not escape, he claimed, since there would be lethal indirect effects such as the demolition of the entire protective ozone layer. The rate of GRBs in the universe today appears to be about one burst per galaxy per several hundred million years. http://www.daviddarling.info/encyclopedia/G/gamma-ray_burst.html Thursday, April 29, 2010 29
  30. 30. X-ray binaries & X-ray bursters http://www.roe.ac.uk/roe/support/pr/pressreleases/050608-ultracam/index.html Thursday, April 29, 2010 30
  31. 31. Millisecond Pulsars This animation attempts to condense the billion year evolutionary history of such a binary system into a few tens of seconds. It begins with two stars, one more massive than the other, in a tight orbit. The massive star evolves first and swallows up its companion, which spirals into it forming an even tighter binary system. The core of the massive star produces a supernova and leaves behind a neutron star. The neutron star's companion eventually begins to lose mass and forms an accretion disk around the neutron star. The accretion of material onto the neutron star causes it to spin faster and faster, eventually reaching a spin period of a few milliseconds. The accreted material produces X-rays which in turn can begin vaporizing the companion. All that remains at the end is a highly compact, rapidly rotating neutron star which produces a pair of radio beams and may be observable as a millisecond radio pulsar. http://heasarc.gsfc.nasa.gov/docs/ xte/Snazzy/Movies/millisecond.html Thursday, April 29, 2010 31
  32. 32. Stellar Remnants LACC §: 22.1, 22.2, 23.5 • White Dwarfs (Chandrasekhar mass limit = 1.4 M ): the dead carbon cores (<~1.4 M ) of low mass stars (<~10 M ) left behind after a Planetary Nebulae • Neutron Stars and Pulsars: neutron degenerate remnants (1.4 < 3 M ) of high mass stars (>~10 M ) left behind after a Type-II Supernovae • Black Holes (>3 M ): ∞ dense remnants of high mass stars (>~10 M ) after a Type-II Supernovae An attempt to answer the “big questions”: What is out there? Where did I come from? Thursday, April 29, 2010 32
  33. 33. LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed. • Ch. 23, p. 532: 4. Due at the beginning of next class period. Test covering chapters 14-23 next class period. Thursday, April 29, 2010 33
  34. 34. Review for Test (4 of 5): Stars [10 pts] The Sun [10 pts] Nebulae, Binary Systems & Stellar Remnants • proton-proton chain (hydrogen nucleus, proton, positron, • nebulae: molecular clouds, HII regions (star forming gamma rays, helium nucleus), the neutrino problem regions, planetary nebulae, supernova remnants), • interior → atmosphere: core, radiation zone, convection reflection nebulae, supernova remnants zone, photosphere, chromosphere, corona, solar wind • nova and type-I supernova: binary system with a white • solar phenomena (solar magnetic field): granules dwarf, light curves; X-ray binaries and X-ray bursters: sunspots, flares, prominence/filaments, coronal mass binary system with a neutron star or black hole; accretion ejection, aurora and geomagnetic storms (on Earth) disks • stellar remnants: masses, sizes, densities of white dwarfs [10 pts] Stars vs. neutron star vs. black holes; pulsars; black holes • stellar spectra: temperature, spectral class, radial velocity (singularity, Schwarzschild radius, event horizon) (red-shift vs. blue shift), composition, cluster age (main sequence turn-off) [10 pts] Identify from an Image or Chart • determining distances: (radar (closest planets/asteroids • solar surface features: sun spots (umbra, penumbra), only)), stellar parallax, standard candles--e.g. main granules, prominence, flare, coronal mass ejection; sequence fitting, RR Lyrae and Cepheid variables nebulae: molecular clouds, star forming HII region, • other properties: proper motion, luminosity, apparent planetary nebulae, reflection nebulae brightness/magnitude vs. absolute brightness/magnitude, • HR Diagram: regions--main sequence, white dwarfs, spectroscopic or eclipsing binaries to determine mass giants, supergiants, spectral class, luminosity class; axes-- x-axis = temperature, spectral class; y-axis = luminosity, [10 pts] Stellar Evolution absolute magnitude; mass & age & main sequence--high • HR Diagram: x-,y-axes, evolutionary tracks mass at top left, short lifetimes; low mass at lower right, • low mass evolution: Hayashi track, main sequence (H long lifetimes; main sequence turn-off point gives a star core burning), red giant branch (H shell burning), helium cluster’s age flash (He core ignition), horizontal giant branch (He core • Make use of a chart containing the following stellar data: burning), asymptotic giant branch (He shell burning), apparent magnitude (mv), absolute magnitude (Mv), planetary nebulae (envelope ejection), white dwarf spectral class, luminosity class • high mass evolution: similar to low mass stars, but keep fusing elements up to iron, type-II supernova (gamma ray burst), neutron star (pulsar) or black hole Thursday, April 29, 2010 34

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