Star Life Cycles and the H-R Diagram Key Question: How can we use an H-R diagram to know where a star is in its life cycle?

Stars STARS: a review

Main Ideas Stars make light There are different types of stars Stars have different life cycles

Stars make light through fusion HYDROGEN HYDROGEN

Not everything we see at night is a star.

Objects like the moon and planets reflect light from our star, the sun.

Which of the following does not reflect light? A: comets B: planets C: Stars D: Moons

There are many different types of stars

Since there are so many stars scientists have classified them by size temperature color brightness

To see connections all stars are graphed in the H-R diagram The H-R Diagram shows the temperature, size and amount of light a star makes.

For now, our sun is a MAIN SEQUENCE STAR. An average mid-life star

What type of star would be in this section? GIANTS OR SUPER GIANTS

The life of a star depends on its mass

Life of the Sun

Life of a Massive Star

Which type of star will be part of the sun’s life cycle? A: neutron star B: super red giant C: white dwarf D: blue dwarf

Nebula a huge cloud of gas (mostly hydrogen) and dust

Supernova An explosion of a large star

Dwarf Star With no more energy flowing outward, nothing prevents gravity from crushing the matter in the core together When hydrogen fusion stops, the core glows brightly

Neutron Star It is smaller than a white dwarf Its core has collapsed to become very dense

Black Hole This is when an enormous supernova explodes and then the core collapses completely and vanishes It has a huge amount of gravity

Which one should you circle?