Finding the Milky Way in the Galaxy

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Slide 1

The Milky Way

Center, Shape

Globular cluster system

Galactic coordinates

Size of the Milky Way

Slide 2

Milky Way from Iowa

Slide 3

Milky Way from Australia

Slide 4

Milky Way from Australia

Slide 5

How do we locate the center of the Milky Way?

Can’t see center directly with visible light because of obscuring clouds in the plane of the Galaxy

Look above the plane of the galaxy

Slide 6

Slide 7

Slide 8

M15

Slide 9

M13

Slide 10

Globular clusters

Compact, spherical group of stars

Up to several 100,000 stars

All stars formed together, same age

Form a halo around the Milky Way

Slide 11

Globular cluster system

Slide 12

Globular cluster system

Centered on the center of the Milky Way

Extends far above and below the plane

By observing globular clusters, we can determine the direction to the center of the Milky Way (and, later, our distance from the center).

Slide 13

Globular clusters in Sagittarius

Slide 14

Galactic coordinates

Slide 15

Globular clusters are found primarily in what part of the Milky Way?

Halo

Disk

Central 1 kpc

Bulge

Disk and Bulge

Slide 16

Size of the Milky Way

How do we find the size of the Galactic halo or the distance to the Galactic center?

Star counts, as described in the text book, are a bad way.

Slide 17

Pulsating stars