Finding the Milky Way in the Galaxy

Page
4

mass and age

orbital speed and distance from the center

Slide 40

The Milky Way in various wavelengths

Milky Way in infrared, radio

The 21 cm line of Hydrogen

Slide 41

Milky Way from Australia

Slide 42

Scattering of light

Blue light is scattered more

Red light is transmitted more

Stars seen through dust appear redder than they really are

If we want to try to see through dust, what kind of light should we use?

Slide 43

Electromagnetic spectrum

---------- radio ------------

Slide 44

Milky Way in optical light

Slide 45

Milky Way in infrared light

Slide 46

Milky Way in radio waves

Slide 47

Hydrogen emits 21 cm radio waves

Slide 48

Same effect in other atoms is used to do magnetic resonance imaging (MRI)

Slide 49

Spiral arms

Tracers of spiral structure

Objects found in spiral arms

How are the spiral arms formed?

Slide 50

Spiral arms

Slide 51

Tracing spiral arms

Slide 52

Spiral arms can be traced from the positions of clouds of atomic hydrogen

To do this yourself, read 19.5-19.6

Slide 53

21 map of spiral arms

Slide 54

Tracers of spiral arms

Young stars and related objects also trace spiral arms

Emission nebulae = H II regions

Molecular clouds

Clusters of young (O and B) stars

Slide 55

Spiral arms

Slide 56

Why can't we see visible radiation from the central region of the galaxy?