Topic #4 Beyond Our solar system

1. Section #1: Properties of Stars Topic #4 Beyond Our solar system

2. Stars in the night sky display many characteristics and patterns. Noticeable patterns seen among stars are called constellations and they are used to designate regions of the sky. Stars in the region of a constellation are considered part of the constellation…even if they are not a part of the pattern. There are 88 constellations. The Night sky

4. Stars are the large balls of gas that give off electromagnetic radiation…just like our sun which is a star. Understanding star characteristics gives us an understanding of the universe. Characteristics of Stars

5. The amount of energy given off by a star is determined by its temperature. We can’t measure the temperature of stars millions of light years away but we can use their color to identify temperature. Star color and temperature

6. More then half of the stars in the universe orbit another star and they are called binary stars. Gravity causes them to orbit each other and an objects gravity can be used to identify its mass. With knowing a stars orbit and gravitational attraction scientists can guess the stars mass. Binary Stars and Stellar Mass

7. The motion of stars is hard to determine because the earth is constantly moving. In fact the Earth has moved 18,641.15 miles in the amount of time it took us to read this sentence. Measuring distance to stars

8. The motion of the Earth causes a shift in the apparent position of a star called parallax. The closer a star the greater the parallax. Scientists take a picture of a star and then take another 6 months later and they find the middle of the two different parallax angles and can say that that is the actual location of a star. Measuring Distance to stars

10. Stars are so far away that their distance isn’t measured in miles it is measured in light years. A light year is the distance light can travel in 1 year. This unit is based on the constant speed of light and is roughly 9.5 trillion kilometers. Measuring Distances to stars

11. A stars brightness is called its magnitude. • A stars brightness as it appears from Earth is its apparent magnitude. • This is determined by a stars size, its heat and its distance from earth. Stellar brightness

12. The actual brightness of a star is called its absolute magnitude. The factors that determine a stars apparent magnitude can make two stars with the same absolute magnitude look like they have different brightnesses. Stellar Brightness

13. A Hertzsprung-Russell Daigramshows the relationship between a stars absolute magnitude and its temperature. 90% of stars fall into the region of the diagram in the upper left called the main sequence. Red giants and Supergiantsare extremely large and bright stars found in the upper right hand corner of the diagram. Hertzsprung-Russell diagram

15. A star is born in a cloud of gas and dust called a nebulae. As some stars age they increase and decrease their brightness and this change in brightness is due to explosion of energy called a nova. Star life changes