Podcast
Questions and Answers
Match the following characteristics with their corresponding galaxy type:
Match the following characteristics with their corresponding galaxy type:
Elliptical galaxy (E) = Round, no disk, very little gas and dust, only old stars Spiral galaxy (S) = Central bulge, flattened disk, spiral arms, gas, dust, young stars Barred-spiral galaxy (SB) = Elongated central structure, flattened disk, spiral arms, gas and dust, young stars Irregular galaxy (Irr) = Asymmetric, often with gas, dust, and young stars
Hubble's galaxy classification includes types such as _______ and _______.
Hubble's galaxy classification includes types such as _______ and _______.
elliptical, spiral
Which properties are associated with irregular galaxies? (Select all that apply)
Which properties are associated with irregular galaxies? (Select all that apply)
Which galaxy types exhibit significant star-forming activity?
Which galaxy types exhibit significant star-forming activity?
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Rank the galaxies based on the speed with which they should be moving away from Earth: 5 billion light-years, 2 billion light-years, 800 million light-years, 230 million light-years, 70 million light-years.
Rank the galaxies based on the speed with which they should be moving away from Earth: 5 billion light-years, 2 billion light-years, 800 million light-years, 230 million light-years, 70 million light-years.
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Rank the galaxies based on their distance from Earth: 130,000 km/s, 45,000 km/s, 18,730 km/s, 5,265 km/s, 1,577 km/s.
Rank the galaxies based on their distance from Earth: 130,000 km/s, 45,000 km/s, 18,730 km/s, 5,265 km/s, 1,577 km/s.
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Rank the galaxies based on the amount of redshift observed in each galaxy's spectrum: 130,000 km/s, 45,000 km/s, 18,730 km/s, 5,264 km/s, 1,577 km/s.
Rank the galaxies based on the amount of redshift observed in each galaxy's spectrum: 130,000 km/s, 45,000 km/s, 18,730 km/s, 5,264 km/s, 1,577 km/s.
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Rank the graphs based on their predictions of speed for a galaxy located 400 million light-years away from Earth.
Rank the graphs based on their predictions of speed for a galaxy located 400 million light-years away from Earth.
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Rank the graphs based on the prediction they each would make for the current age of the universe.
Rank the graphs based on the prediction they each would make for the current age of the universe.
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Study Notes
Hubble's Galaxy Classification
- Galaxies are classified into four types based on shape: elliptical, spiral, barred-spiral, and irregular.
- Elliptical Galaxies (E): Round, lack a distinct disk, contain minimal gas and dust, comprised mostly of old stars.
- Spiral Galaxies (S): Feature a central bulge and a flattened disk with spiral arms, rich in gas and dust, and host young stars.
- Barred-Spiral Galaxies (SB): Similar to spiral galaxies but have an elongated central structure; also contain gas, dust, and young stars.
- Irregular Galaxies (Irr): Asymmetrical, often with significant gas, dust, and young star populations.
Irregular Galaxy Properties
- Irregular galaxies may show signs of past collisions with other galaxies.
- They typically exhibit vigorous star formation activity.
- Characteristics like tightly wound spiral arms and concentrated starlight do not apply to irregular galaxies.
- Generally, irregular galaxies are smaller than spiral galaxies.
Star-Forming Activity in Galaxies
- Galaxies exhibit varying levels of star formation activity.
- Low Star-Forming Activity: Observed in elliptical galaxies.
- Significant Star-Forming Activity: Found in irregular, spiral, and barred-spiral galaxies, indicating vibrant star development.
Understanding Hubble's Law
- Hubble's Law posits that galaxy speed increases with distance from Earth.
- Distance Categories for Galaxies:
- 5 billion light-years
- 2 billion light-years
- 800 million light-years
- 230 million light-years
- 70 million light-years
- This principle implies that farther galaxies recede faster due to the universe's expansion.
Galaxy Speed Ranking
- Galaxies can be ranked by their speed moving away from Earth:
- Faster galaxies are found at greater distances.
- Approximate speeds of galaxies:
- 130,000 km/s
- 45,000 km/s
- 18,730 km/s
- 5,265 km/s
- 1,577 km/s
Redshift Observations
- Redshift measures the extent of a galaxy's movement away from Earth.
- Larger redshift values correlate with higher speeds, revealing the dynamics of cosmic expansion.
Visualizing Hubble's Law
- Graphs depicting Hubble's Law illustrate relationships between galaxy distances and speeds.
- Steeper slopes in these graphs suggest faster galaxy speeds at specific distances.
Predictions about the Universe's Age
- The graphs of Hubble’s Law can also be used to infer the current age of the universe based on their slopes.
- Rankings of graphs can categorize predictions from oldest to youngest regarding cosmic evolution.
Summary
- Hubble's classification helps understand galaxy structures and star formation.
- The insights into galaxy speeds and redshift are pivotal in studying cosmic expansion and the universe's age.
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Description
Test your knowledge on Hubble's galaxy classification with these flashcards. Learn about the different types of galaxies including elliptical, spiral, barred-spiral, and irregular, along with their characteristics. Perfect for Astronomy 201 students preparing for exams.
