Star Properties!!

Constellation A. A grouping of stars (ex. Big Dipper) - named after animals, mythological creatures, and everyday objects.

4. Constellation. - Today, there are 88 4. Constellation - Today, there are 88. - Some constellations you can see year-round, others only in specific seasons.

Clusters of Stars Star Cluster- A group of stars that is gravitationally bound to each other- they interact with each other. Binary Stars- two stars that orbit around a common center of mass, and are very close to each other.

Stellar Distances A. Light year - the distance light travels in a year - (it has nothing to do with time). - It is 9,500,000,000,000 km. - Used to show distance to stars

Stellar Distances – B. Parallax - the METHOD used to determine the distance to stars. - The star appears to move because Earth is moving. - Scientists can look at the angle of apparent movement to determine how far away the star is.

Star Color vs. Star Temperature A. Hot Stars- stars that are 30,000 K or hotter are blue. Medium Stars- stars in the middle range appear yellow. Cool Stars- stars in the 4,000 K or less range are red.

6. Star Color vs. Star Temperature

Hertzsprung-Russell Diagram A. Y-axis is absolute magnitude B. X-axis is the temperature of star

Hertzsprung-Russell Diagram C. Main Sequence Stars - Stars on a curve that runs diagonally through the graph - 90% of all stars are main sequence. - Hot and bright stars to cool and dim stars

The Hertzsprung-Russell Diagram

Hertzsprung-Russell Diagram D. White Dwarf - Small, dim, and hot - Few are White Dwarfs E. Red Giants - Large, bright and cool - Few are Red Giants

The Hertzsprung-Russell Diagram

Hertzsprung-Russell Diagram F. Our sun is average in size and temperature (main sequence star)

Star Composition Most stars are about 73% hydrogen and 25% helium!!