1. Chapter 30.1: Characteristics of Stars

2. Characteristics of Stars A star is a _________________________ _______________________________ ____. Size varies Color varies__________________. Our sun is an average star

3. Composition Star composition observed through a spectrometer Separates light _________________________. Each color represents a different wavelength Three types of spectra - - - Since different elements absorb different wavelengths of light, elements can be determined.

4. Composition Continued __________is the most common element. Surface temperature of a star is indicated by the color _________are the coolest and _______ are the hottest (Figure 2 on page 776).

5. Motion Two kinds of motion associated with stars: ____________--- just like it sounds! ____________--- This is motions visible to the unaided eye in a dark sky; due to movement of Earth.

6. Motion Continued Some stars create circular trails around a central star (Polaris aka the North Star) - Different stars become visible during different seasons. Three actual motions: 1. 2. 3.

7. Distance Light Year = 9.5x10 12 km; Distance that light travels in one year. Astronomical Unit (AU) _________ _____________________________ ________________.

8. Stellar Magnitude Magnitude:_______________________________ _______________________________. Apparent magnitude = brightness of a star as it appears to us on Earth Measure light from star using telescopes Measurement is then assigned a number Brightest stars have lowest numbers Dimmest stars have highest numbers Absolute:___________________________.