4. Constellation
A. A grouping of stars (ex. Big Dipper) - named after animals, mythological
creatures, and everyday objects.
4. Constellation - Today, there are 88.
- Some constellations you can see year-round, others only in specific seasons.
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.
5. 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
5. 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.
6. Star Color vs. Star Temperature
A. Hot Stars- stars that are 30,000 K or hotter are blue.
B. Medium Stars- stars in the middle range appear yellow.
C. Cool Stars- stars in the 4,000 K
or less range are red.
6. Star Color vs. Star Temperature
7. Hertzsprung-Russell Diagram
A. Y-axis is absolute magnitude
B. X-axis is the temperature of star
7. 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
7. 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
7. 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!!