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Astronomy:What is the fascination?

Presented by Jim Burnell

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Nearly everything we see in the sky is part of the great cycle of stellar birth, life,

death and rebirth.

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Our fascination with astronomy stems from our

own quest to understand our place in the universe.

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The Birth of a Star

• Stars are born in groups, inside huge clouds of gas and dust.

• These star forming regions are called nebulae

• The earliest nebulae contained only Hydrogen and Helium, and a trace of Lithium

5NGC2237 – The Rosette Nebula

6M8 – The Lagoon Nebula

7M42 – The Orion Nebula

8IC1396

9VdB 142 – The Elephant’s Trunk Nebula

10M16 – The Eagle Nebula

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Nebulae

• Spiral galaxies, like our own Milky Way are filled with these nebulae.

• The nebula are formed by denisty waves that compress the gas and dust in the interstellar medium.

• They trace out the spiral arms.

12M31 – The Great Andromeda Galaxy

13M33 – The Pinwheel Galaxy

14M51 – The Whirlpool Galaxy

15NGC253 – The Silver Dollar Galaxy

16NGC5198 – Centaurus A

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The Life of a Star

• Most stars are born in groups called clusters.

• Over time, these clusters often dissipate, spreading the stellar family across the galaxy.

• Stars like our sun live for ~ 10 billion years.

18M45 – The Pleiades

19M24 – The Sagittarius Star Cloud

20NGC2477

21The Double Cluster

22M46

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The Death of a Star:a Peaceful Death

• Most stars die a gentle death, burning their hydrogen, then their Helium and then ejecting their outer layers.

• This forms a so-called Planetary Nebula.

• Planetary Nebulae are some of the most beautiful objects in the universe.

24M27 – The Dumbell Nebula

25NGC7293 – The Helix Nebula

26M76 – The Little Dumbell Nebula

27M57 – The Ring Nebula (taken by the HST)

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The Death of a Star:a Violent Death

• Large stars die a spectacular death, exploding in a Supernova.

• The energy expended in a supernova can briefly exceed all the energy radiated by the host galaxy.

• Thousands of years after the explosion, a cloud of debris expands many lightyears into nearby space, dissipating.

29M1 – The Crab Nebula

30The Veil Nebula

31Simeis 147 – Supernova Remnant in Taurus

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Supernovae:Fathers of the Next Generation of Stars

• Though the death of a star in a supernova explosion is the most violent activity in the universe, it is the furnace in which the heavier elements are forged.

• The supernova explosions seeds the interstellar medium with these heavy elements

• Out of them the next generation of stars is reborn.

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Supernovae:The Precursors of Life

• These heavy elements are a critical part of plant and animal (and human) life.

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