1. Stellar Characteristics

2. Temperature Temp. is measured in Kelvins Blue stars are hot, above 30,000 K Yellow stars are warm Red stars are cool, below 3,000 K

4. Star streaks (4 hr time-lapse)...there ARE different color stars!

5. Mass Size can be small, medium or massive Binary Stars: when two stars orbit around each other Stars of equal mass have their center of mass in the middle

8. to stabilize the teeter totter, the center of mass has to be closer to the big kid if astronomers see the two stars orbiting like this, it helps them determine which star is bigger

9. Distance Parallax used for nearby stars the inverse square law of light is used for distant stars Light year = 9.5 trillion km Parsec = 3.3 light years

10. Parallax

11. Magnitude = brightness apparent magnitude: star’s brightness as it appears to us absolute magnitude: how bright a star actually is Bright stars are negative and dim stars are positive Magnitude

12. which star is the brightest?

13. Chemical Composition The elements a star is made of Each element has a unique spectral line, like a fingerprint

14. Emission spectrum of Hydrogen, H Emission spectrum of Iron, Fe

15. #1What does a Kelvin measure? star’s name star’s brightness star’s composition star’s temperature

17. #2 Order the stars from coolest to hottest yellow - blue - red? answer: red - yellow - blue

18. #3 It is hard to measure the size of a star, but what can we use to help? Binary star system Binomial star system light year parallax

19. Binary star system

20. #4 Dim or Bright? Compare the following absolute magnitudes: -2 absolute magnitude : 10 absolute magnitude :