6. The fate of super-massive stars

7. Supermassive stars (> 25 M ☉ ), will collapse under a force of gravity which is so strong that nothing can escape its pull - not even light. They become.

8. Death of a giant star 25 to 100

9. Hertzsprung - Russell Diagram Main Sequence Stars Supermassive stars 25 – 100 X the mass of the sun…

10. Hertzsprung - Russell Diagram Main Sequence Stars Supermassive stars 25 – 100 X the mass of the sun turn into Red Supergiants.

11. The fate of super-massive stars

12. Around a black hole If no light can escape from a black hole, how can we “see” them to know that they really exist?? Black holes pull in swirling clouds of gas from neighboring stars. These gases are moving so fast that they become very hot…

13. Around a black hole Very hot objects give off streams of X-Rays. When astronomers first found a strong X- ray source with no star is visible at that location (using a regular light telescope), they figured that it must be a black hole - a massively huge star that has collapsed under its own weight and “winked out” of visibility.

14. X-Ray images of Cygnus X-1 (First Discovered Black Hole)

15. X-Ray images of black holes Where do the X-Rays come from??

16. Black Hole with Plasma Jet Event horizon Accretion disk Plasma jet

17. Accretion Disc swirling from binary twin toward the event horizon Binary Star System Black Hole

18. Hot Swirling Gases of Accretionary Disk Give Off X-rays

19. X-rays also come from plasma jets

20. Tidal Forces

21. Approaching a black hole Tidal forces are caused by gravity pulling with different degrees of force on objects which are different distances from the gravity source.

22. Tidal forces and ocean tides High Tide Low Tide

23. (Ex: the center of the earth is 4,000 miles farther from the moon than the oceans, moon’s gravity pulls harder on the ocean, creating tides)

24. Tidal forces and ocean tides High Tide Low Tide

25. Tidal forces and ocean tides

26. Spring Tides: Sun and moon pull together - Higher tides; Neap Tides: Sun works against Moon – Tides not as high High Tide Low Tide

27. Black holes have an incredibly huge masses packed into an incredibly tiny point called a singularity. This causes the force of gravity to skyrocket. Tidal forces and black holes

28. Tidal forces Approaching a black hole As a result, the distance needed to create a noticeable tidal force is very small: A 6 foot tall human approaching a black hole would have much greater gravity pulling on his feet than on his head.

29. Approaching a black hole The tidal forces would s t r e t c h him like “Gumby”. This would actually pull the person apart (as well as his spacecraft) as he approached the event horizon:

30. “Spaghettification”

31. The event horizon The event horizon is the “edge” or boundary of the black hole - the “point of no return” (and no escape). All matter which passes the event horizon is trapped inside the black hole forever.

32. The event horizon If a spaceship reached this point intact, it would not be able to send signals back - the radio waves and microwaves would be pulled back by the black hole’s immense gravity.

33. The event horizon From a distance, the space- ship would appear to be permanently hovering on the event horizon. Once inside the event horizon, all matter is shredded and compressed down to a single point called the singularity.

34. The event horizon The “Point of no Return”

35. Accretion disk

36. Accretion Disk

37. verse or even to an entirely different universe! The scientists know that a black hole can be formed by the death of a very massive star. During the stable life of the star, radiation and heat and gravity remain in balance. When the star exhausts its nuclear fuel. However, it begins to collapse. As its volume diminishes to zero, its gravity and density becomes infinitely great. It is now what physicists call a “singularity”. The star has literally crushed itself out of this universe. …as the robot passes through the “accretion disc” of swirling gases, gravitational tides begin to stretch it…

38. Of course, there is a slim chance that the robot might survive after all, according to some theories, the black hole might act as a “wormhole” or passageway to another part of the universe or even to an entirely different universe! Spaceship observers see the robot hovering at the “event horizon” - the “point of no return” - from which even the robot’s radio messages cannot escape. as the robot is sucked in, all its molecules and atoms are shredded, and it is compressed into the singularity.

39. Gravitational Lens –- Black Hole bends light from distant star.

40. Gravitational Lens –- Black Hole bends light from distant star.

41. Gravitational microlensing Black Hole bends light from distant star. Microlensing creates a single, overlapped brighter image

42. Beyond black holes…

43. Wormhole – Gateway to another universe??

44. Worm hole vs black hole A worm hole is a funnel that tapers down to a “throat” (but doesn’t pinch off) which connects to another funnel that opens up somewhere else. A black hole is a funnel that pinches off at a singularity. A traversable worm hole needs to be large and “mellow” enough that it doesn’t have an event horizon (a black hole’s “point of no return”), or any fatal tidal forces.

45. Beyond black holes…

46. Review –- 3 lifecycles of stars 8 to 25 25 to 100 8

47. Star cycles Old “starstuff” becomes the fuel for new stars. Small-Medium Stars Large Stars