Star Systems and Clusters
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| Binary Star |
Vocab- binary stars: a star system with two stars
Facts- Star systems that contain two stars are called double stars or binary stars. In a binary star, one star is usually has more luminosity and is more massive. Not only that, but you can also tell when there is a dim star because of the effects of its gravity. Since the dim star revolves around the bright star it causes the bright star to wobble. Astronomers can tell when it's a binary star because one of the stars can be seen from Earth.
Example- If two dancers are twirling each other around, but can't see the invisible dancer only the visible one is noticeable. You can still see the invisible dancer because of the motions of the visible one.
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| Example of eclipsing binary stars |
Vocab- eclipsing binary: a system in which one star periodically blocks the light from another
Facts- Wobbling isn't the only sign of a dim star/companion. The dim star from a binary star could pass in front of another bright star to eclipse it.
3.Planets around other stars
Facts- "In 1995, astronomers first discovered a planet revolving around another ordinary star" (Pearson Education, Inc.). These astronomers studied the star to conclude that it might be a planet because it didn't have enough mass. Since this discovery, astronomers have found over 100 planets around other stars. We are still finding new ones all the time! Now astronomers are wondering if there might be life on planets outside our solar system that we don't know about.
4.Star clusters
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| Open cluster |
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| Globular cluster |
Facts- Most stars go into larger groupings which are called star clusters. "All of the stars in a particular cluster formed from the same nebula at about the same time and are about the same distance from Earth" (Pearson Education, Inc.). Open clusters and globular clusters are the two major types of star clusters. Open clusters contain many bright supergiants, gas, and dust. Whereas globular clusters are round and densely packed. They might contain more than a million stars.
Galaxies
1.Galaxies in space
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| Milky way (galaxy) |
Vocab- galaxy: a huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity
Facts- Many large galaxies, like our own, appear to have a black hole at their center. There are tons of galaxies in the universe. Galaxies have billions of stars. Large galaxies have trillions of stars.
2.Quasars
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| Quasar |
Vocab- quasars: an enormously bright, distant galaxy with a giant black hole at its center
Facts- Astronomers discovered objects that were very bright. These things were far away. They are the most distance objects in the universe.Since they are really bright, they could almost pass as a star. These were concluded to be quasars that are active young galaxies with giant black holes at their centers.
Types of Galaxies
1.Spiral galaxies |
| Spiral Galaxy |
Vocab- spiral galaxies: a galaxy with a bulge in the middle and arms that spiral outward in a pinwheel pattern
Facts- The spiral galaxies arms contain many bright young stars. Also including gas and dust.The new stars usually from in the spiral arms. Not only that, but spiral galaxies are also called barred-spiral galaxies.
2.Elliptical galaxies
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| Elliptical galaxy |
Vocab- elliptical galaxies: have shapes that are round, like balls, or oval, like eggs
Facts- They contain millions of stars, but lack dust and gas. Since there is only a little amount of gas or dust, there isn't any stars forming. Most of these type of galaxies contain only old stars.
3.Irregular galaxies
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| Irregular Galaxy |
Vocab- irregular galaxies: a galaxy that does not have a regular shape
Facts- They are typically smaller than other types of galaxies. Also, they contain young stars, gas, and dust to form new stars. These galaxies are located near larger galaxies. The larger galaxies might of distorted the shape of irregular galaxies.
The Scale of the Universe
1.Scientific notation
Vocab- scientific notation: uses powers of ten to write very large or very small numbers in shorter form
2.The immensity of space
Facts- Since the size varies in our universe, we use scale of these structures. Then we would use scientific notation to help us put it in a shorter form.
Key Questions
What is a star system?
- Most stars are members of groups of two or more stars, called star systems.
What are the major types of galaxies?
- Astronomers classify most galaxies into three main categories: spiral, elliptical, and irregular.
- Our solar system is located in a spiral galaxy called the Milky Way.
How do astronomers describe the scale of the universe?
- Since the numbers astronomers use are often very large or very small, they frequently use scientific notation to describe sizes and distances in the universe.
