Week 4, clip 11

Timepoint 03:04.4

1) Both stars in this image are at the same distance.  Why does Dr. Plesser say they cannot both be Main Sequence stars?

- Blue-white stars are White Dwarfs, which are never on the Main Sequence.
- Bright, red stars are Red Giants, which is not part of the Main Sequence.
- Hot, blue Main Sequence stars are always more luminous than cool, red Main Sequence stars.
- Blue-white light represents extremely hot temperatures that only come from gas falling into an very dense object like a neutron star or black hole.

Answers:
1) Hot, blue Main Sequence stars are always more luminous than cool, red Main Sequence stars.