14 galaxies island universes. 14 copyright – fors1 vlti, european southern observatory

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14 14 Galaxies Galaxies Island Universes

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Page 1: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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GalaxiesGalaxies

Island Universes

Page 2: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414Copyright – FORS1 VLTI, European Southern Observatory

Page 3: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Ellipticals

Page 4: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Ellipticals

• Huge• No gas.• No dust.• No young

stars.• Nothing but

old stars.– Random

orbits.

Page 5: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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M 87 Copyright – Anglo-Australian Telescope Board

Copyright - HST

Page 6: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Spirals

Page 7: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Spirals

• Like Milky Way.• Disks and

bulge.• Young stars

and old.• Gas and dust.• Stars forming.• Stars dying. M81 and M82 – Copyright R. Gendler

Page 8: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414M63 Copyright – S. Miyazaki, Suburu

Page 9: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414NGC1365 Copyright – VLT

Page 10: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414M31 The Andromeda Galaxy Copyright – Jason Ware

Copyright – S. Miyazaki, Suburu

Page 11: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414M33 – Copyright NOAO

Page 12: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414M51 - Copyright HST

John P. Gleason

Page 13: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414NGC 4314

Page 14: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414NGC 891 – Copyright J.C. Barentine, NOAO

NGC 891 – Copyright WIYN

Page 15: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

1414Sombrero Galaxy – Copyright P. Barthel VLT

M10 – copyright Credner and Kohle

Page 16: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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NGC 4526

Page 17: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Irregulars

Page 18: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Nearby Galaxies

• Cepheids.• Period.• Luminosity

abs. mag.• Know app. Mag• Get Distance.

10pc

distancelog5 10Mm

Page 19: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Groups

Page 20: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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The Local Group

Page 21: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Clusters

Page 22: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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The Virgo Cluster

Page 23: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Page 24: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Distant Galaxies

• Can’t see individual stars.• Can use nearby galaxies to get

distances to further galaxies.• Distance ladder:

– Parallax nearby stars– Nearby stars H-R diagram– H-R diagram distant stars (variables)– Variable stars nearby galaxies– Nearby galaxies ?

Page 25: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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21cm Radiation

• Neutral hydrogen (HI) gives off radiation at 21cm.

Milky Way HI emission – Copyright J. Dickey

Page 26: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Extragalactic HI

• Observe HI in other galaxies.• Measure wavelength of 21 cm radiation.• Get velocity away from us.

Page 27: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Hubble’s Law

• Measure the velocity of every galaxy.

• Nearly all are redshifted.

• Use Cepheids to measure distances to nearby galaxies.

• Result: The faster it’s moving, the farther away it is.DH v

distance velocity

o

Page 28: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Map the Universe• V = HoD

• If you know Ho:

• Measure v• Get D• Find:

VoidsWalls

Clusters

Page 29: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Page 30: 14 Galaxies Island Universes. 14 Copyright – FORS1 VLTI, European Southern Observatory

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Homework #12Homework #12

• Read: Bennett Ch 22.1 – 22.4• Do Ch22:

– Problems: 1, 6, 9, 12– Math folks substitute problem 18 for 9 and

12.