Download Studying the Stars

Studying the Stars
Parallax, Magnitude & H-R
Diagram
Parallax
Magnitude (History)
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Magnitude is a measure of the
brightness of a star.
In 1856, British astronomer Norman
Pogson proposed a scale of stellar
magnitudes.
– He noted that we receive 100 times more
light from a first magnitude star as from a
sixth.
Magnitude
(Orders of Magnitude)
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Negative numbers are the brightest,
positive numbers are the dimmest.
– The naked eye can see down to around
the sixth magnitude (that is +6).
– Galileo saw about magnitude 9 with his
telescope.
– The Hubble Space Telescope? About
magnitude 29.
Magnitude
(Apparent vs. Absolute)
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Apparent Magnitude: How bright a
star appears from Earth
Absolute Magnitude: How bright a
star really is (if you could see them all
from the same distance)
Classifying Stars
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All stars can be organized on the
Hertzsprung-Russell Diagram
Star classification system (Early 1900’s)
x-axis = temperature
y-axis = brightness
Shows main sequence, white dwarfs,
giants and supergiants
H-R Diagram