Stars Expectations: D2.3, D2.5,

How do Stars Differ? Size Mass Brightness /Luminosity: is a measure of the total amount of energy radiated by a star or other celestial object per second Composition Temperature Colour

Different Stars

More Massive Stars

Life Cycle of Stars Nebula: birthplace of a star, made of gas and dust

The life of a star is determined by its mass. The more massive the star, the faster its rate of nuclear fusion and therefore a shorter life.

Hertzsprung-Russell Diagram

Composition of Stars Spectral Analysis Astronomers can use spectroscopes to identify the composition of stars Each element has a unique set of absorption/emission lines.

Composition of Stars Spectral Analysis Here are spectra for some elements common in the atmospheres of stars: Here are the spectrums of mystery stars: 1 2 3

Composition of Stars Spectral Analysis Here are spectra for some elements common in the atmospheres of stars: Here is the spectrum of a mystery star: 1 has the following elements: Iron Magnesium 2 has the following elements: Iron Calcium 3 has the following elements: Iron Calcium Hydrogen

Comparing Stars and Planets A star is matter that emits huge amounts of energy. A planet is matter, generally spherical, that revolves around a star. Feature Planet Star Location In the solar system Beyond the solar system Distance from Earth Fairly near Very far Real size Smaller than most stars Usually larger than planet Reason we see object Reflects Sun’s light Emits its own light Surface temperature Usually cool or very cold Very hot What object is made of Usually rocks or gases Gases under high pressure & temperature Observable feature Has a steady light Appears to twinkle Long-term observable feature Very slowly wanders through constellations Appears to move through sky as part of a constellation

Classwork Worksheets (HR diagram & Life Cycle of Stars) Read p. 370-373 Answer page 373 #1-3, 5, 7-9 Read p. 375-382 Answer page 382 #3-4, 6, 7, 9