spiral galaxies. elliptical galaxies irregular galaxies

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Spiral Galaxies

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Page 1: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Spiral Galaxies

Page 2: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Elliptical Galaxies

Page 3: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Irregular Galaxies

Page 4: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Classification of Galaxies

Page 5: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Properties of Galaxies

Spirals Ellipticals IrregularsMass [typical; range]

(solar masses)

1011 ;

109 - 1012

1011.5 ;

106 - 1013

1010 ;

108 - 1011

Size (pc) 104- 105.5 104- 106 103- 105

Color Blue arms,

reddish bulge

reddish bluish

Luminosity 108 - 1010 105 - 1011 107- 109

Stellar Populations Pops I & II Pop II Pop I (Pop II)

Interstellar medium Yes Very little Still some

Rotation Yes (disk) no Not a lot

Fraction 30% 20% 50%

Other galaxy types : Peculiar, Interacting, Ring, Starburst, Dwarf,Luminous Infrared, Active Nuclei, Damped Lyman-alpha

Page 6: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Stephan’s Quintet – Colliding galaxies

Page 7: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

The “Anntenae” Galaxies – a case study

Page 8: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Galactic Train Wrecks

Page 9: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Collisional Aftermath

Page 10: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Ring Galaxies – the “splash”

Head-on collisions can produce a “ripple” of star formation that expands outwards.

Page 11: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Galactic Superwinds

Page 12: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

The Magellanic

Clouds

Large Magellanic Cloud Small Magellanic Cloud

Southern Hemisphere only

Page 13: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

The Galactic Neighborhood

Page 14: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

The “Local

Group” of Galaxies

Page 15: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Members of the Local Group

Page 16: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

And outward…

Page 17: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Galaxy Clusters

Virgo

Coma

Notice the giant ellipticals at the centers of many clusters.These are an example of “galactic cannibalism”.

Page 18: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Galactic Cannibals – Central CD Ellipticals

At the heart of rich clusters, galaxies pass through the center and are disrupted and collected.

Page 19: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Making a CD galaxy

Page 20: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

into the Universe…

Page 21: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Large Scale Structure

On the largest scales (100 million ly) the Universe takes on a “foamy” appearance, with great filaments and walls of galaxies and clusters, surrounding great “voids” that are relatively empty.

Page 22: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Dark Matter - rotation curvesRotation curves imply the mass-to-light ratios of galaxies go up as we look on larger scales: Sun M/L=1, solar neighborhood M/L=3, galaxy M/L=50

Page 23: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Dark Matter – cluster speeds

galaxy clusters M/L=200-500

From average speed of galaxies – the cluster would fly apart

From X-ray gas held in – several million degrees and extensive

Page 24: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

What could the dark matter be?

1) Normal but dark matter (“baryonic”) : rocks, white or brown dwarfs?

2) Black holes or neutron stars? Too much metals would have been produced.

Anyway, there is a fundamental reason from the Big Bang this can’t be it…

Page 25: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

Dark Matter :gravitational

lensing The mass required to produce the observed lensing is much higher than the luminous mass. This is a direct observation of gravity due to dark matter.

Page 26: Spiral Galaxies. Elliptical Galaxies Irregular Galaxies

WIMPS and Cold Dark MatterCould dark matter be some kind of new particles which

interact very weakly with matter (like neutrinos do) but massive, and not moving relativistically? Experiments at Berkeley and elsewhere are looking for them (guaranteed Nobel prize!).