Questions and Answers
What is a barred spiral galaxy?
A spiral galaxy in which the spiral arms begin from the ends of a bar running through the nuclear bulge.
What is a cluster of galaxies?
A collection of a few hundred to a few thousand galaxies bound by their mutual gravitational attraction.
What defines an elliptical galaxy?
A galaxy with an elliptical shape, little interstellar matter, and no spiral arms.
What is galactic cannibalism?
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What is a galactic merger?
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What is gravitational lensing?
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What is the Hubble classification?
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What is the Hubble constant?
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What does Hubble flow refer to?
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What is Hubble's law?
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What is intergalactic gas?
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What is an irregular cluster of galaxies?
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What defines an irregular galaxy?
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What is a lenticular galaxy?
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What is the Local Group?
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What is a poor cluster of galaxies?
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What is a regular cluster of galaxies?
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What is a rich cluster of galaxies?
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What is a spiral density wave?
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What defines a spiral galaxy?
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What is a standard candle in astronomy?
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What is a starburst galaxy?
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What is a supercluster of galaxies?
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What is a trailing-arm spiral galaxy?
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What does the Tully-Fisher relation describe?
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What are the least massive galaxies in the universe?
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Spiral density waves are directly responsible for what?
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Which of the following statements about the motion of galaxies is correct?
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What is the common name for the sonic boom created by lightning?
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In spiral galaxies, what spectral classes of stars are only found in spiral arms?
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What is the Hubble classification scheme?
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Study Notes
Key Galaxy Types
- Barred Spiral Galaxy: Features spiral arms emerging from a central bar structure.
- Elliptical Galaxy: Lacks spiral arms, has an elliptical shape and minimal interstellar matter.
- Irregular Galaxy: Asymmetrical with no defined shape or structure.
- Lenticular Galaxy: Disk-shaped, similar to spiral galaxies but without spiral arms.
- Spiral Galaxy: Defined by its rotating, flattened shape and spiral arms originating from the nucleus.
Galaxy Collections
- Cluster of Galaxies: Contains hundreds to thousands of galaxies held together by gravity.
- Local Group: A cluster comprising approximately 40 galaxies, including the Milky Way.
- Supercluster: A massive gravitational structure containing multiple galaxy clusters.
- Rich Cluster: A galaxy cluster featuring a substantial number of member galaxies.
- Poor Cluster: Composed of only a few galaxies.
Galaxy Interactions
- Galactic Cannibalism: Occurs when a larger galaxy absorbs a smaller one during a collision.
- Galactic Merger: Involves the merging of two galaxies of comparable size.
Galaxy Dynamics
- Hubble's Laws: Describes the relationship between galaxy distance and recession speed, establishing that distances influence motion away from Earth.
- Gravitational Lensing: A phenomenon where gravity distorts the view of distant objects.
Star Formation and Characteristics
- Spiral Density Wave: A pressure wave in spiral galaxies that encourages new star formation.
- Starburst Galaxy: Describes galaxies experiencing an exceptionally high star formation rate.
- Standard Candle: An astronomical object with a known luminosity used to calculate distances to galaxies.
- Classes O and B Stars: These high-mass stars are exclusively found in spiral arms, formed in actively star-forming regions.
Other Concepts
- Hubble Constant: Vital for determining the universe's age based on galaxy recessional velocity.
- Tully-Fisher Relation: Correlates the width of the 21-centimeter line in spiral galaxies with their absolute brightness.
- Irregular Cluster of Galaxies: Characterized by an uneven distribution of galaxies, unlike regular clusters that are evenly distributed.
Miscellaneous
- Gravitational Interactions: Superclusters are observed to be receding from one another, indicative of the expanding universe.
- Supersonic Boom: Refers to the sound produced by lightning, analogous to the concept of a sonic boom.
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Description
Explore key concepts from Astronomy Chapter 16 with these flashcards. Learn definitions related to different types of galaxies and their characteristics. Perfect for students looking to enhance their understanding of galaxy classifications.