The Milky Way Galaxy

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Pollution proceeds fastest near Galactic centre

Older stars have fewer heavy elements

Radial migration leads to big spread in [Fe/H] at given age

Slide 14

Velocity space from Hipparcos

Distribution of stars lumpy in velocity space

Pointer to the Galactic bar and spiral structure

Slide 15

Stars trapped by the bar

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Interstellar Gas

Systematic effect: circular streaming

Slide 17

CO

HI

Slide 18

The Galactic Bar

Gas towards the GC moving away at ~150km/s

Slide 19

Expected if Galaxy barred

to Sun

Slide 20

If we could look down

Slide 21

Near IR Photometry

Galaxy brighter on left of GC

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Individual objects (eg HB stars) also brighter on left

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The Galactic Centre

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Sgr A and Filaments

Slide 25

Inclined Nuclear Disk

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The Black Hole

Weak radio source Sgr A* marks spot

Orbiting stars reveal its force-field

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Globular Clusters

M3

100 000 stars

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Halo & Disk Clusters

Disk

Halo

Slide 29

Disk clusters more metal-rich

Also a population of field stars traced by blue horizontal branch stars & RR Lyrae stars

many from destroyed globular clusters

Slide 30

Stellar halo (SDSS)

residuals

Bell et al

(2007)

Slide 31