STARS

Most of the information we have about stars comes from the study of our star, Sol aka Sun

 Structure of a star

 Properties of stars - COLOR  Color determines temperature  Blue/white - extremely hot & bright and young  White  Yellow  Orange  Red - cool & dim and usually old

 36B521BB69A03E0DCA8D36B521BB69A 36B521BB69A03E0DCA8D36B521BB69A WHY ARE THERE NO GREEN STARS?

 Properties of stars  BRIGHTNESS is also called Luminosity and is determined by a stars ABSOLUTE & APPARENT MAGNITUDE  Stars can look big to us because  They are close  They are big  They are very hot  They are bright

 Properties of a star MASS (size)  Supergiants are the largest stars, and may have diameters several hundred times the size of the Sun.  Giants are more common than Supergiants, and have diameters 10 to 100 times as large as the Sun.  Medium-size or about as large as the Sun  White dwarfs are small dying stars (about the size of the planet EARTH).  Red Giants & Super massive red giants are dying stars, have cooler temperatures than other stars, and are not as bright, but their size is still massive. Mass the amount of matter ( particles) the star contains Stars are classified by mass and color

 Properties of stars - mass  A stars mass determines its life cycle  Smaller mass stars live or last longest and may live hundereds of billions of years  Massive and Super Massive stars have very short life times only billions of years

 Properties of stars Diameter  Diameters of stars are determined by gathering three pieces of information;  1) distance  2) brightness  3) and color

WHY DO STARS TWINKLE? The scientific name for the twinkling is stellar scintillation (or astronomical scintillation).  Stars twinkle when we see them from Earth because we are viewing them through the thick layers of Earth’s moving atmosphere  the light of the star is bent (refracted) many times and in random directions  Stars closer to the horizon appear to twinkle more than stars that are overhead  Stars do not appear to twinkle when viewed from outer space or from a planet/moon that does not have an atmosphere

DO STARS TWINKLE?