Ch. 15-1 Stars Chapter 19, Section 1 Part 1

Stars Stars are huge, hot, brilliant balls of gas. To learn about stars, scientists study starlight.

Color of Stars Look at the candle and Bunsen burner. Which is hotter? The blue flame of the Bunsen burner is much hotter than the yellow flame of the candle. Stars are different colors too, so we know they are different temperatures.

Composition of Stars The rainbow of colors produced when white light passes through a prism is the spectrum. A spectrograph is used to spread starlight out into its colors.

Making an ID Absorption spectra show what elements are in a star’s atmosphere. For example, this spectrum shows the presence of hydrogen.

Absorption Spectrum of the Sun Our sun shows absorption lines for hydrogen (marked with an H) and other heavier elements.

Classifying Stars Stars are classified by how hot they are. Different surface temperatures result in different colors.

Brightness of Stars The lower the magnitude = the brighter the star. (Sun = -26.8) Magnitude means size, or in this case brightness.

2 Ways To Look At Brightness Apparent Magnitude – How bright the star really looks from Earth. The farther away from us, the dimmer the star looks. Absolute Magnitude – How bright the star really is. If all stars were the same distance from us, how bright would it look compared to the other stars.

Let’s Try It! Looking at Stellar Hearbeat