chapter 21
DESCRIPTION
Chapter 21. 21.4 Star Systems and Galaxies. Double and Triple Stars. Most solar systems have more than one star. Solar systems with 2 stars are called binary systems. Solar systems with 3 stars are called triple stars - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/1.jpg)
CHAPTER 2121.4 Star Systems and Galaxies
![Page 2: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/2.jpg)
Double and Triple Stars Most solar systems have more than one
star. Solar systems with 2 stars are called
binary systems. Solar systems with 3 stars are called triple stars
The stars orbit each other, and when one star passes in front of another star it is called an eclipsing binary system
The effects of gravity often clue astronomers to the presence of the 2nd star by a distinct wobble the star has when it orbits.
![Page 3: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/3.jpg)
Extrasolar planets The pull of gravity is one of the ways that
astronomers have used to discover planets orbiting other stars. A different more subtle wobble indicates the presence of planets.
More than 400 planets have been found orbiting other stars.
Technology is not good enough to detect Earth like planets yet, but it is getting better all the time.
![Page 4: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/4.jpg)
Galaxies A galaxy is a collection of stars,
dust, and gas that usually orbits a supermassive black hole and contains billions of stars.
There are 3 kinds of galaxies:SpiralEllipticalIrregular
![Page 5: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/5.jpg)
Spiral Galaxies Have a pinwheel shape. Our galaxy, the
Milky Way, is a spiral galaxy
![Page 6: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/6.jpg)
Elliptical Galaxies They are older galaxies that lack a lot of
dust and gas. Star formation has virtually ceased as a
result.
![Page 7: Chapter 21](https://reader035.vdocuments.us/reader035/viewer/2022070421/568162f8550346895dd372ee/html5/thumbnails/7.jpg)
Irregular Galaxies Galaxies that have odd shapes are called
irregular galaxies. The odd shapes come from collisions with
other galaxies.