1. A Universe of Galaxies
Galactic Cannibalism and the Ultimate Fate of our own Galaxy (the Milky Way)
Guest Lecture
A110-A
03 November, 2017

2. Guest Lecture - foreword
Current events:
1. Sunrise 6:36 am
Sunset 5:54 pm
Lunar phase: Full Moon
2. news articles:
Discovery of Neptune
Today - Lecture + Highlight questions
Neptune discovered by John Galle
(23 September, 1846)
The blue clouds of Neptune are mostly
frozen methane, the main chemical in
natural gas. The other object shown
is Neptune's moon Triton.
Guest Lecture
A110-A
03 November, 2017

3. The Milky Way our home Galaxy
Figure 15–10 (C) Another spiral galaxy, M100 in the constellation Coma Berenices, imaged with the European Southern Observatory’s Very Large Telescope.

4. Long exposure wide-angle lens photo of the night sky
Figure 15–10 (C) Another spiral galaxy, M100 in the constellation Coma Berenices, imaged with the European Southern Observatory’s Very Large Telescope.
The “Milky Way”

5. Charles Messier and his catalog of “nebulous objects”
1770’s - French astronomer Charles Messier
cataloged ~100 “fuzzy objects” so that he would
ot mistake them for comets.
This catalog became very useful because it
contained the brightest “fuzzy objects”, and
therefore the best candidates for further study.
Messier’s objects (now know by their “M” numbers
(e.g. M1, M2 … M100) hold the key to much of our
understanding of the constitutent parts of our own
Milky Way galaxy, and to other nearby Galaxies.
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

6. Charles Messier’s “spiral nebulae”
Figure 15–10 (C) Another spiral galaxy, M100 in the constellation Coma Berenices, imaged with the European Southern Observatory’s Very Large Telescope.
Charles Messier’s “spiral nebulae”

7. Figure 15–10 (A) The drawing shows our Milky Way Galaxy’s nuclear bulge surrounded by the disk, which contains the spiral arms. The globular clusters are part of the halo, which extends above and below the disk. From the fact that most of the clusters appear in less than half of our sky, Shapley deduced that the galactic center is in the direction indicated.

8. Disk Nucleus Spheroid Halo Corona
The constituent parts of our Galaxy - the Milky Way
Disk
Nucleus
Spheroid
Halo
Corona
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

9. Our “Local Group” of Galaxies
Figure 15–10 (C) Another spiral galaxy, M100 in the constellation Coma Berenices, imaged with the European Southern Observatory’s Very Large Telescope.

10. The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

11. Our nearest large neighbor Galaxy - M31 (Andromeda)
Figure 16–4 The Andromeda Galaxy, also known as M31 and NGC 224, is the nearest large spiral galaxy to the Milky Way. Its Hubble type is Sb, and it is accompanied by two small elliptical galaxies, M32 (left of middle) and NGC 205 (lower middle). These galaxies are only 2.4 million light-years from Earth. The older red and orange stars give the central regions of M31 a yellowish cast, in contrast to the blueness of the spiral arms from the younger stars there.

12. Edwin Hubble at the Mt. Wilson 60” telescope
Figure 16–5 Edwin Hubble, who did his groundbreaking work at the Mt. Wilson Observatory above Los Angeles, California. Here he is shown at the Palomar Observatory, near San Diego, California.
Edwin Hubble at the
Mt. Wilson 60” telescope

13. Spirals, Ellipticals, Irregulars
Galaxy Types:
Spirals, Ellipticals, Irregulars
Normal and Active
Figure 15–10 (C) Another spiral galaxy, M100 in the constellation Coma Berenices, imaged with the European Southern Observatory’s Very Large Telescope.

14. The Galaxy “Tuning-Fork” Diagram
“Normal Galaxies”
The Galaxy “Tuning-Fork” Diagram
Figure 16–6 (A) The Hubble “tuning fork” classification of galaxies. It is not meant to imply an evolutionary sequence among galaxies.

15. Figure 16–6 (B) Images of all the Hubble types of galaxies, taken during the Sloan Digital Sky Survey. At top right we see a row of galaxies edge-on and a row face-on.

16. Figure 16–7 (A) An edge-on view of NGC 4565, a type Sb spiral galaxy in the constellation Coma Berenices. The dust lane in the plane of the galaxy can be seen.
An edge-on view of NGC 4565, a type Sb spiral galaxy in the constellation Coma Berenices

17. The “Sombrero” galaxy (M104) in the constellation Virgo
Figure 16–7 (B) The Sombrero galaxy (M104) in the constellation Virgo is also seen close to edge-on, with its dust lane showing prominently.
The “Sombrero” galaxy (M104) in the constellation Virgo

18. A Barred spiral galaxy (SBbc), NGC 1365 in the constellation Eridanus
Figure 16–8 A barred spiral galaxy, NGC 1365, in the constellation Eridanus.
A Barred spiral galaxy (SBbc), NGC 1365 in the constellation Eridanus

19. Normal Galaxies: brief summary
Ellipticals - mostly Spheroidal distribution of old stars,
(very few, if any, new stars being formed)
surrounded by a Halo containing many Globular Clusters,
surrounded by an large extended Corona of hot gas
Spirals - smallish Spheroid accompanied by a prominent
Disk of “youngish stars” + gas&dust,
(lots of new stars being formed)
surrounded by a Halo containing Globular Clusters,
surrounded by an extended Corona of hot gas
Irregulars - mostly small irregular Disks of young and old stars
- no globular clusters + small Halo and Corona
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

20. The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

21. 1 July, 1990
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

22. Chapter Opener: The Mice, NGC 4676, with long tails of stars and gas drawn out as two galaxies collided, imaged with the Advanced Camera for Surveys that was installed in 2002 on the Hubble Space Telescope. Supercomputer simulations show that we are seeing two spiral galaxies approximately 160 million years after their closest encounter.
NGC “The Mice”

23. “The Antennae” Galaxy Pair
Figure 16–12 (A) The peculiar, interacting spiral galaxies NGC 4038 and NGC 4039, known as The Antennae. False color (optical: green and white; radio: blue) is used to highlight the tidal tails in this view.
“The Antennae” Galaxy Pair

24. enhanced star formation going on in the disks of
Figure 16–12 (B) A Hubble Space Telescope close-up of The Antennae that shows details of gas and dust in the two central regions.
Closer picture of the
enhanced star formation
going on in the disks of
the 2 spiral galaxies that
make up “The Antennae”

25. The “Cartwheel” Galaxy
Figure 16–13 A Hubble Space Telescope image of the Cartwheel Galaxy, in the constellation Sculptor, a ring galaxy probably caused by one of its satellite galaxies passing through it.

26. The Great Observatories Allsky Luminous-infrared-galaxy Survey
GOALS
Figure 16–13 A Hubble Space Telescope image of the Cartwheel Galaxy, in the constellation Sculptor, a ring galaxy probably caused by one of its satellite galaxies passing through it.

27. Merger (Spiral + Spiral)
“The Mice”
Stars only

28. Spiral + Spiral => Elliptical
Gas only

29. The Grand Design of the Universe of Galaxies
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

30. Super-clusters of galaxies and Voids
(the grand design of the Universe)
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

31. The nearest rich cluster of galaxies
Figure 16–17 The central part of the extensive Virgo Cluster of galaxies, the nearest large cluster to the Milky Way Galaxy. Fewer than a dozen of the roughly 1000 cluster galaxies are visible here.
The central part of the Virgo Cluster distance = 60 Mly = 18Mpc

32. The nearest very-rich cluster of galaxies
Figure 16–18 The extremely rich Coma Cluster, containing over 10,000 galaxies, only a fraction of which are visible in this image. There are two dominant, large elliptical galaxies.
The Coma Cluster distance = 300Mly = 90Mpc

33. 1994
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

34. throughout the Universe, but are arranged
A 3-Dimensional View of the Universe of Galaxies
Galaxies are NOT distributed randomly
throughout the Universe, but are arranged
in filamentary structures sometimes referred
to as the “Cosmic Web” in an overall pattern
of “sheets” and “voids”
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

35. - The arrangement of Superclusters and Voids
The “Cosmic Web”
- The arrangement of Superclusters and Voids
into the grand design of the Universe
Figure 16–37 This supercomputer calculation of the formation of clusters of galaxies shows the existence of filaments and voids. The details of the results depend on whether cold dark matter, hot dark matter, or a mixture of the two fills the Universe.

36. 2004
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.

37. 3-D Computer simulation of the development of cosmic structure
Figure 16–37 This supercomputer calculation of the formation of clusters of galaxies shows the existence of filaments and voids. The details of the results depend on whether cold dark matter, hot dark matter, or a mixture of the two fills the Universe.

38. The “Local Group” – Andromeda and the Milky Way
Take away Points:
Our galaxy:
Milky Way spiral
Our galaxy group:
The “Local Group” – Andromeda and the Milky Way
are the 2 largest members of this ~30 galaxy group
Our “ultimate fate”:
Merger with M31(Andromeda) in ~5 billion years
The end result:
The formation of a giant elliptical galaxy and the
triggering of an active nucleus (quasar). The active
nucleus will grow to a billion solar mass black hole.
The illusion of stars all lying at the same distance in the constellations allows us to define the celestial sphere. It doesn’t really exist, but it’s a useful tool for learning about the sky. When discussing this slide, be sure to explain:
North celestial pole
South celestial pole
Celestial equator
Ecliptic
It’s also very useful to bring a model of the celestial sphere to class and show these points/circles on the model.