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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 _______.
elliptical, spiral
Which properties are associated with irregular galaxies? (Select all that apply)
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.
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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.
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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.
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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.
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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.
