1. Stars, Their Lives, And The Stuff In Between Sarah Silva Program Manager Sonoma State University NASA Education and Public Outreach

2. The NASA E/PO Program at Sonoma State University A group of seven people working collaboratively to educate the public about current and future NASA high energy astrophysics/astronomy missions. Led by Prof. Lynn Cominsky Swift GLAST XMM-Newton

3. What do we know about stars?

4. Life Cycles of Stars

5. Classifying Stars Hertzsprung-Russell diagram Stars spend most of their lives on the Main Sequence

6. Stars and Balloons Volunteers Please

7. Stars and Balloons Imagine we have: 12 - Red Balloons 12 - Yellow Balloons 4 - White Balloons 2 - Blue Balloons OR Roughly 80% red and yellow, 15% white, and 5% blue.

8. Preparation: Place 1 wooden bead inside each red and yellow balloon. Place 1 marble inside each white balloon. Place 1 ball bearing inside each blue balloon.

9. Stars and Balloons Red Balloons ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars Yellow Balloons 1 Solar Mass (the mass of our Sun): Yellow Stars White Balloons 3 Solar Masses (3 times the mass of our Sun): White Stars Blue Balloons 9 Solar Masses (9 times the mass of our Sun): Blue Stars Please blow up your balloon until it has a 3 inch diameter.

10. 5 Million Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars Wait. Do not change diameter of balloon. Blow slightly more air into balloon.

11. 10 Million Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars Wait. Blow up a little moreBlow up star as fast and as much as you can. When star is fully inflated, -a supernova.

12. 500 Million Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars WaitWait (note: planets are forming) Continue to slowly inflate star. As it gets bigger, star cools, so color it yellow and red (make squiggles on surface with markers). This popped star has become a black hole; all of the super nova remnants can be thrown out into space.

13. 1 Billion Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars WaitBlow up a little bit.Quickly blow up star until fully inflated; pop balloon. Make sure to catch marble Still black hole!

14. 8 Billion Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars WaitBlow up more. The star is getting cooler, so color it red with marker. It is now a supergiant. This star has exploded. Holding on to neutron star (marble), throw supernova remnants into space. Place remnants in a recycle bin to demonstrate stellar gas is recycled into new star matter. Still black hole

15. 10 Billion Years Red Balloons Yellow Balloons White BalloonsBlue Balloon ↓0.4 Solar Mass (2/5 the mass of our Sun): Red stars 1 Solar Mass (the mass of our Sun): Yellow Stars 3 Solar Masses (3 times the mass of our Sun): White Star 9 Solar Masses (9 times the mass of our Sun): Blue Stars WaitBlow up a little more. Outer envelope dissolves, so cut up balloon. The inside bead becomes a white dwarf, and the bits of balloon represent the planetary nebula. Neutron starStill black hole

16. Reprise: the Life Cycle Sun-like Stars Massive Stars

17. Molecular clouds and protostars Giant molecular clouds are very cold, thin and wispy– they stretch out over tens of light years at temperatures from 10-100K, with a warmer core They are 1000s of time more dense than the local interstellar medium, and collapse further under their own gravity to form protostars at their cores BHR 71, a star-forming cloud (image is ~1 light year across)

18. Protostars Orion nebula/Trapezium stars (in the sword) About 1500 light years away HST / 2.5 light years Chandra/10 light years

19. Stellar nurseries Pillars of dense gas Newly born stars may emerge at the ends of the pillars About 7000 light years away HST/Eagle Nebula in M16

20. HR Diagram again as a reminder

21. Main Sequence Stars Stars spend most of their lives on the “main sequence” where they burn hydrogen in nuclear reactions in their cores Burning rate is higher for more massive stars - hence their lifetimes on the main sequence are much shorter and they are rather rare Red dwarf stars are the most common as they burn hydrogen slowly and live the longest Often called dwarfs (but not the same as White Dwarfs) because they are smaller than giants or supergiants Our sun is considered a G2V star. It has been on the main sequence for about 4.5 billion years, with another ~5 billion to go

22. Pro Fusion or Con Fusion? The core of the Sun is 15 million degrees Celsius Fusion occurs 10 38 times a second Sun has 10 56 H atoms to fuse 10 18 seconds = 32 billion years 2 billion kilograms converted every second Sun’s output = 50 billion megaton bombs per second

23. 10 18 seconds is a long time… but it’s not forever. What happens then? Don’t Let the Sun Go Down on Me

24. The Beginning Of The End: Red Giants After Hydrogen is exhausted in core... Energy released from nuclear fusion counter-acts inward force of gravity. Core collapses, and kinetic energy of collapse converted into heat. This heat expands the outer layers. Meanwhile, as core collapses, Increasing Temperature and Pressure...

25. More Fusion ! At 100 million degrees Celsius, Helium fuses: 3 ( 4 He) --> 12 C + energy (Be produced at an intermediate step) (Only 7.3 MeV produced) Energy sustains the expanded outer layers of the Red Giant

26. Stellar evolution made simple Stars like the Sun go gentle into that good night More massive stars rage, rage against the dying of the light Puff! Bang! BANG!

27. How stars die Stars that are below about 8 M o form red giants at the end of their lives on the main sequence Red giants evolve into white dwarfs, often accompanied by planetary nebulae More massive stars form red supergiants Red supergiants undergo supernova explosions, often leaving behind a stellar core which is a neutron star, or perhaps a black hole

28. Red Giants and Supergiants Hydrogen burns in outer shell around the core Heavier elements burn in inner shells

29. Fate of high mass stars After Helium exhausted, core collapses again until it becomes hot enough to fuse Carbon into Magnesium or Oxygen. 12 C + 12 C --> 24 Mg OR 12 C + 4 H --> 16 O Through a combination of processes, successively heavier elements are formed and burned.

30. Heavy Elements from Large Stars Large stars also fuse Hydrogen into Helium, and Helium into Carbon. But their larger masses lead to higher temperatures, which allow fusion of Carbon into Magnesium, etc.

31. Supernova !

33. Crab nebula and pulsar X-ray/Chandra

34. Neutron Stars and Pulsars

35. If neutron stars are made of neutral particles, how can they have magnetic fields? Neutron stars are not totally made of neutrons-- the interiors have plenty of electrons, protons, and other particles. These charged particles can maintain the magnetic field. Plus, a basic property of magnetism is that once a magnetic field is made, it cannot simply disappear. Stars have magnetic fields because they are composed of plasma, very hot gas made of charged particles.

36. Magnetic Globe Demo

37. A Burst By Any Other Name… Neutron star: dense core leftover from a supernova Possess incredibly strong magnetic fields Soft Gamma Ray Repeater: violent energy release due to starquake Accretion: neutron star draws matter off binary companion Matter piles up, undergoes fusion: bang! Cycle repeats: X-Ray Burster

38. Flash! The fading afterglow, seen for the first time in X-rays

39. Swift Mission Burst Alert Telescope (BAT) Ultraviolet/Optical Telescope (UVOT) X-ray Telescope (XRT) Launched November 20, 2004

40. Swift Mission Will study Gamma-Ray Bursts with “swift” response Survey of “hard” X-ray sky Launched November 20, 2004 Nominal 2-year lifetime Will see ~150 GRBs per year

41. Birth of a Black Hole Long bursts (>2 seconds) may be from a hypernova: a super-supernova Short bursts (<2 s) may be from merging neutron stars Both create nature’s vacuum cleaner: a black hole

42. Gamma-ray Bursts Either way you look at it – hypernova or merger model GRBs signal the birth of a black hole!

43. What Is A Black Hole? –Not just a vacuum cleaner –If you take an object and squeeze it down in size, or take an object and pile mass onto it, its gravity (and escape velocity) will go up.

44. Black Hole Structure Schwarzschild radius defines the event horizon R sch = 2GM/c 2 Not even light can escape, once it has crossed the event horizon Cosmic censorship prevails (you cannot see inside the event horizon) Schwarzschild BH

45. Black Hole Space Warp Record the following questions based on your observations. 1.What do the moving balls represent? 2.What does the weight represent? 3.What happened to the balls? 4.What does the blue latex material represent? 5.What happens to the material when the bouncy balls roll around?

46. Masses of Black Holes Primordial – can be any size, including very small (If <10 14 g, they would still exist) “Stellar-mass” black holes – must be at least 3 M o (~10 34 g) – many examples are known Intermediate black holes – range from 100 to 1000 M o - located in normal galaxies – many seen Massive black holes – about 10 6 M o – such as in the center of the Milky Way – many seen Supermassive black holes – about 10 9-10 M o - located in Active Galactic Nuclei, often accompanied by jets – many seen

47. How Do Black Holes Form? Stellar-mass black holes –Supernova: an exploding star. When a star with about 25 times the mass of the Sun ends its life, it explodes. –called a “stellar-mass black hole,” or a “regular” black hole –Stellar-mass black holes also form when two orbiting neutron stars – ultra-dense stellar cores left over from one kind of supernova – merge to produce a short gamma-ray burst.

48. Where Are Black Holes Located? Let’s think…. They form from exploded stars… We have one at the center of the Milky Way…. The nearest one discovered is still 1600 light years away Black holes are everywhere!

49. Evidence This shows ten years worth of Prof. Ghez’ data at 2.2 microns of the stars orbiting around a 4 million solar mass black hole at the center of the Milky Way. It also shows the star’s orbits extrapolated into the future Note: Stars S0-2 and S0-16 provide the best data

50. Supermassive Black Holes Normal galaxy –A system of gas, stars, and dust bounded together by their mutual gravity. VS. Active galaxy –An galaxy with an intensely bright nucleus. At the center is a supermassive black hole that is feeding.

51. Galaxies and Black Holes Zooming in to see the central torus of an Active Galaxy. Jet Accretion disk Black Hole

52. Resources 1 st Section – Stellar Cycle Balloon Activity –Adler Planetarium: http://www.adlerplanetarium.org/education/teachers/pl ans/gravity/9-12_gq5-1.shtml http://www.adlerplanetarium.org/education/teachers/pl ans/gravity/9-12_gq5-1.shtml 2 nd Section – Supernova and Magnetic Globe –http://xmm.sonoma.edu/edu/supernovahttp://xmm.sonoma.edu/edu/supernova 3 rd Section – Black Holes Space Time Warp –http://glast.sonoma.edu/teachers/blackholeshttp://glast.sonoma.edu/teachers/blackholes –My Email: sarah@universe.sonoma.edu

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54. The Supernova Connection GRB011121 Afterglow faded like supernova Data showed presence of gas like a stellar wind Indicates some sort of supernova and not a NS/NS merger

55. Iron lines in GRB 991216 Chandra observations show link to hypernova model when hot iron-filled gas is detected from GRB 991216 Iron is a signature of a supernova, as it is made in the cores of stars, and released in supernova explosions

56. Hypernova A billion trillion times the power from the Sun The end of the life of a star that had 100 times the mass of our Sun movie

57. Catastrophic Mergers Death spiral of 2 neutron stars or black holes