Term
| Name the four types of Galaxy. |
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Definition
1. Spiral
2. Barred Spiral
3. Elliptical
4. Irregular |
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Term
| Describe a Spiral Galaxy. |
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Definition
Spirals arms wound round the nucleus.
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Term
| Describe a Barred Spiral Galaxy. |
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Definition
Spirals extend from a bar through the nucleus. |
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Term
| Describe an Elliptical Galaxy. |
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Definition
A general ellipse shape. Some are spherical, some are cigar shaped. Typically they are brighter towards the centre. |
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Term
| Describe an Irregular Galaxy. |
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Definition
Irregular galaxies do not fit into the tuning fork diagram and usually bear no relation to the shapes of other galaxies or have any obvious symmetry. Their strange shape may have arisen because of disturbances from other galaxies. |
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Term
| How are Galaxies Classified? |
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Definition
Edwin Hubble classified galaxies according to their shape. He produced a Tuning Fork Diagram as he thought this demonstrated the evolution of elliptical galaxies into spirals. |
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Term
| Describe the Tuning Fork Diagram. |
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Definition
- Elliptical galaxies are classified from E0 (Spherical Galaxies) to E7 (Very Elongated)
- Spiral galaxies are classified Sa (The spirals extend from the nucleus outwards with a slight bend) to Sc (The spirals are wrapped around the nucleus tighter)
- Irregular galaxies are not part of the Hubble Classification.
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Term
| What are the three types of Active Galaxy? |
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Definition
1. Seyfert
2. Blazers
3. Quasars |
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Term
| What is an Active Galaxy? |
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Definition
| Active galaxies are galaxies that have a small core of emission (the production electromagnetic radiation by an atom or other object.) embedded at the centre of the galaxy. |
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Term
| Describe Seyfert Galaxies. |
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Definition
| These have bright spectral emission lines caused by either the accretion disc, or from a highly ionized gas around the nucleus. gas that rotates the black hole faster shows a broader emission line. Typically Seyfert galaxies are spiral or irregular. |
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Term
| Describe Blazer Galaxies. |
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Definition
| Blazers are active galaxies that have jets pointing towards Earth. They are quite variable, and emit Radio and X Rays. |
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Term
| Describe Quasar Galaxies. |
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Definition
| Quasars are active galaxies that emit Radio and X Rays. They have extremely large black holes at their centre and are moving away from us at very fast rates. They are the furthest and oldest objects we know of (some are as far as 11 billion light years away). |
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Term
| What galaxy is the Milky Way converging with? |
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Definition
Sagittarius Dwarf galaxy. In several million years' time, the larger Andromeda galaxy (M31) will converge with the Milky Way and form a larger galaxy. |
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Term
| What is the nearest Galaxy to us? |
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Definition
Large Magellanic Cloud orbiting just 170,000 light years away from us. |
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Term
| What is the closest Spiral Galaxy to the Milky Way? |
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Definition
Andromeda Galaxy, the largest galaxy in the Local Group is 2 million light years away. |
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