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Transcript of Stars
How Far Away Are Stars?
O, B, A, F, G, K, M?
Brightness of Stars
How do we measure the distance to stars?
Stars are burning balls of gas, just like our sun!
They come in various sizes ranging from
dwarf stars to main sequence (average) stars to
giant stars to super giant stars.
Stars are like the sun.
They vary in size, color, brightness and temperature.
They are found everywhere in the Universe.
Stars are classified by color.
Each color corresponds to the surface temperature.
Blue is hotter than yellow which is hotter than red.
Each color has 10 divisions.
Stars are found in galaxies.
Each galaxy can have billions of stars in them.
There are billions of galaxies in the universe.
A light year is the distance
light travels in one year.
1 light year is 63,115.2 AU
Alpha Centauri is the nearest star to the sun.
Alpha Centauri is 4.2 light years away.
That means Alpha Centauri is 265,083.84 AU away!
The size of the star is directly
related to the lifespan of the star.
The larger the star the quicker it burns out.
O and B Type Stars
O type stars
Blue in color
Very hot at 31,000K and higher
B type stars
Blue in color
Cooler at 31,000K to 9,750K
A and F Type Stars
A type stars
They are Blue-White in color
Temp between 9,750K and 7,100K
F type stars
White in color
Temp between 7,100K and 5,950K
G and K Type Stars
G type stars
Yellow to yellow white in color
Temp from 5,950K to 5,250K
K type stars
Orange to Red-Orange in color
Temp from 5,250K to 3,950K
M type stars
M type stars
They are red in color
They are the coolest star
Temp ranges from 3,950K to 2,000K
Magnitude is the brightness of a star
The brightness of a star as viewed from
earth is called Apparent Magnitude.
Apparent Magnitude as viewed from Earth.
Problem with Apparent Magnitude
Close stars are bright and far stars are dim.
No way to accurately compare brightnesses.
To solve the problems of apparent magnitude, astronomers use Absolute Magnitude.
This is when we place the stars at the same distance, and then compare the brightness.
This distance is 10 parsecs or 32.8 Light Years
The scale for brightness runs from
-26 to 15 or more.
Negative numbers are very bright
Large positive numbers are very dim
This is the apparent movement
of a stars position.
It is caused by the movement
of the position of the viewer.