07 - Computing Data to Classify Stars Flashcards
the true brightness of star (this light would get dimmer as the distance grows)
intrinsic brightness
a standardized unit for comparing a star to hypothetical average of a star brightness, at 33ly away
absolute visual magnitude
a calculation of total EM energy output for sphere
luminosity
If astronomers know 1. apparent brightness and 2. it’s distance from earth, they can inverse square law to convert for the distance and then find the…
…intrinsic brightness of a star
Just like how light bulbs are measured in watts, astronomers use “intrinsic brightness” with the measurement of:
L. (luminosity), which his the total energy emitted per second, all wavelengths, compared to the Sun.
ex. our sun is 1L.
measure of energy flow from a surface, light in joules (J) per second, on 1 meter squared.
light meter!!
flux
Spectral Sequence are ordered star classes from hot (blue) to cool (red)
O B A F G K M L T Y
failed stars between (2200 to 1300k in the LTY star class)
brown dwarfs
originated in the Netherlands/USA. A plot of intrinsic brightness vs. temperature of stars and absolute magnitude (surface area or luminosity) vs spectral class (Temperature of color)
Hertzsprung-Russell (H-R) Diagram
(practice drawing it out and understanding it!)
upper left to lower right stars, 90% of all normal stars
main sequence
what’s a cool but luminous star thats 10-100 times larger than the sun called?
a giant
what’s a hot and luminous star (generated by nuclear fusion) that’s 1000x the Sun’s diameter called?
a supergiant
what’s a cool, small, low luminosity, completely convection star called on the lower main sequence?
red dwarf
what’s a very hot, little surface = low luminosity, cooling, and 0.01R size of earth star called?
white dwarf
a star’s spectral line width as classification (smaller stars have broader hydrogen Balmer lines)
luminosity class
