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Starbursts and Exploding Galaxies

Starbursts and Exploding Galaxies. Discovery in Astronomy. Human imagination is no match for universe In Astronomy, observations are more fundamental than in physics, biology Cannot experiment with most cosmic objects Our understanding at any time is circumscribed by:

tallulah-williamson
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Starbursts and Exploding Galaxies

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  1. Starbursts and Exploding Galaxies

  2. Discovery in Astronomy Human imagination is no match for universe In Astronomy, observations are more fundamental than in physics, biology Cannotexperiment with most cosmic objects Our understanding at any time is circumscribed by: Limited observational capabilities Limited interpretational capabiliies ("theory")

  3. 1920: A Tranquil Universe • A single extended star system (Sun near center) • Slow dynamical evolution through long-range gravity • Long time scale: 1000 billion years? • No new star formation • Stars formed only during initial state of universe • Stars slowly contracting and cooling from that time

  4. 1955: A Lively Universe • Other galaxies (“island universes”) exist • Basics of stellar structure and evolution understood • Stellar lifetimes range from millions to billions of years, depending on stellar mass • Interstellar medium (gas & dust) known to be important • “Normal” star formation • Cool gas & dust lying in plane of spiral galaxies is slowly but continuously converted to stars • Typical rate, few M_sun per year • Recognized tracers of recent star formation: • Bright, blue stars (massive stars) • Young star clusters • Ionized gas (electrons stripped by ultraviolet photons)

  5. The Orion Nebula: Interstellar Gas Ionized by Massive, Young Stars

  6. NGC 604: Massive Ionized Nebula in Galaxy M33

  7. Spiral galaxy NGC 1232

  8. Spiral galaxy NGC 300 (GALEX)

  9. H II Regions and Supernova Remnants in NGC 6822

  10. Tracers of Recent Star Formation: Blue Stars, Star Clusters and Ionized Gas in NGC 1569

  11. Super Star Clusters (2)

  12. Dark "dust" patches are characteristic ofstar forming regions

  13. Dust Clouds Against the Milky Way

  14. Interstellar “dust grains”: tiny, smoke-like particles absorb light and act to shield/cool gas. Typical gas:to:dust ratio is 100:1 by mass.

  15. optical infrared Dust grains absorb optical light much more strongly than infrared light.

  16. Dust in the plane of spiral galaxy M104

  17. Spiral dust lanes in spiral galaxy M51

  18. 1985: A Violent Universe • Discovery of “starbursts,” where star formation rate can be 10-1000 M_sun/yr lasting a few 100 million years • Key technology: Infrared telescopes • Much of starburst activity is “hidden” by dense dust clouds. Require IR to see through dust. • Starbursts often induced by galaxy collisions or tidal encounters, when cold gas & dust is dumped into deep central potential well • Galaxies can even “merge” together • Other signatures: galactic “winds,”“super star clusters”

  19. Infrared Astronomical Satellite

  20. Electromagnetic Spectrum

  21. M82: slightly eccentric but mild mannered

  22. But revealed in ionized hydrogen to be a: raging psychopath. An “Exploding Galaxy” --- nearest collision- induced starburst

  23. How the picture was made: Subtractive filter imaging Difference:

  24. The galactic wind in M82 is powered by a central Starburst

  25. M82 Neutral hydrogen map M81

  26. Ionized Wind in NGC 3079

  27. The Guitar Galaxy

  28. IRAS-Selected ULIRG Galaxies

  29. Interacting Starburst Systems

  30. Galaxy Gravitational Interactions Produce Starbursts and (sometimes) Mergers

  31. “Super” Star Clusters in M82

  32. “Super” Star Clusters in M82

  33. “The Antennae”: Starburst With Swarms of Super Star Clusters

  34. Evolved super star cluster = Globular Cluster

  35. The End

  36. Discovery in Astronomy: II. Good Ideas • All science is cumulative • Ideas are continually subject to empirical tests • Science discards wrong ideas but retains right ones • There are many more wrong ideas than right ones • Just as important to know wrong ideas as currently accepted “right” ones • Especially important to know why they were wrong • Limited observational capability • Limited interpretational capability (“theory”)

  37. A Galactic Wind in M82 Powered bya Central Starburst

  38. Dust Along the Galactic Plane

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