HR diagrams Flashcards
spectral class types and their colors
O, B, A, F, G, K, M
blue, light blue, white-blue, white, yellow, orange, red respectively
temperature + main sequence lifetime of O + B spectral types
O
- temp: 30, 000+
- 1 - 10 Myrs
B
- temp: 10,000 - 30,000
- 11 - 400 Myrs
temperature + main sequence lifetime of A + F spectral types
A
- temp: 7,500 - 10,000
- 440 Myrs - 3 Gyrs
F
- temp: 6,000 - 7,500
- 3 - 7 Gyrs
temperature + main sequence lifetime of G + K spectral types
G
- temp: 5,000 - 6,000
- 8 - 15 Gyrs
K
- temp: 3,500 - 5,000
- 17 Gyrs
temperature + main sequence lifetime of M spectral type
- temp: 2,500 - 3,500
- 56 Gyrs
why do stars look different
as an object becomes hotter it emits more energy per second = area under the curve. It also emits more short wave(high frequency) radiation. The colour is how the mix of emitted wavelengths appears to our eyes.
luminosity meaning
the amount of energy emitted per second by the surface of a star
brightness vs luminosity
brightness depends on luminosity + distance
luminosity vs radius
L = R^2
luminosity vs temperature
L = T^4
luminosity vs radius + temperature
L = R^2 x T^4
