Our Milky Way in Space and Time

1. Our Milky Way in Space and Time Caty Pilachowski Mini-University 2013

2. Our Journey… • Where in the Galaxy Are We? • The Local Neighborhood • Top Milky Way Destinations! • The Dark Heart of the Galaxy • Formation of the Milky Way • Our Galaxy in the Cosmos

3. Where Are We???

4. A Thin Disk of Stars 100,000 Light Years 100,000 Light Years

5. What Is a Light Year? • The distance light travels in one year (about 6 trillion miles) • Light travels at 186,000 miles per second The Moon is 1 light-second from Earth The Sun is 8 light-minutes from Earth The nearest star, Proxima Centauri, is four light years from the Sun

6. Our Home Halo The Sun Dust Lanes Spiral Arms Disk Galactic Center Hot Young Stars Bulge Light takes 100,000 years to cross the Milky Way

7. Meet the Neighbors • Proxima Centauri • Alpha/Beta Centauri • Most nearby stars are small, dim and cool

8. 100 Light Years

9. 500 Light Years Polaris

10. Orion Nebula X Distance: ~1300 light years

11. Orion Nebula X Distance: ~1300 light years

12. Pillars of Creation X Lower density gas has been eroded away, leaving pillars of higher density gas where stars are forming Eagle Nebula with Hubble

13. X Crab Nebula • The remnant of an exploded star • The explosion was recorded in 1054 CE ESO

14. Ring Nebula X • The remnant of a dying star • The ring will fade, and the central star will become a white dwarf WIYN

15. Globular Cluster X • Messier 3 • Age – 13 billion years • 500,000 stars WIYN

16. Cygnus X-1 X • A binary star containing a black hole • Mass from the star is pulled into the black hole

17. The Galactic Center! In visual light, this region is hidden from us by gas and dust that dim the light by a factor of 10 billion!  

18. The Galactic Center in Infrared Light The dust is transparent to infrared light, and we can see through the gas and dust to observe the Galactic Center

19. The Galaxy hosts a super-massive black hole at its heart! • Orbits of stars around the central mass is consistent with a 4 million solar mass object at the Galactic Center

20. Massive Black Hole! • Detected in infrared, radio, and x-ray light • Mass 4 million times the Sun’s mass • Growing slowly through accretion • All big galaxies host central black holes

21. A Gas Cloud Approaches the Black Hole! • The cloud will pass within 36 light hours next month (July) • ~3 Earth masses • ~2000 miles per sec Animation!

22. The Universe Contains Many Spiral Galaxies We learn about our Milky Way from other galaxies

23. Forming the Milky Way Galaxies like the Milky Way form from the consolidation of many primordial gas clouds • Collisions of gas clouds create bursts of star formation to shape the Galaxy

24. Nearby dwarf galaxy discovered in 1994 in the direction of Sagittarius Distance about 88,000 light years Merging with the Milky Way The Milky Way Is Still Growing

25. Galaxy’s“New”Tidal Stream • Sagittarius orbits the Milky Way • The orbital period is about a billion years • “Tidal stream” of stars from Sagittarius circles the Milky Way

26. The Local Group 2.5 million light years • The Milky Way is part of a small group of galaxies known as the local group • Andromdea Galaxy • Milky Way Galaxy • Triangulum Galaxy • Many small ones

27. Galaxy Collision!

28. The Local Group Is Part of an EVEN BIGGER Group • The Local Group is part of the Virgo Super Cluster of Galaxy Groups

29. Newly Discovered Galaxy! • The Leo P galaxy was just discovered here at IU using the WIYN Telescope • Five million light years from the Milky Way • Undisturbed, in an empty part of nearby space

30. Our Home in the Cosmos