Download Stars, H-R and Life Cycle of Star

There are
MORE than
200 billion,
billion stars in a
universe. Most
stars contain
mainly
hydrogen and
helium.
Star color
Determined
by surface
temperature.
HOTTEST STAR: shines with a
blue-white light
COOLEST STAR: shines with a red
light
Star Temperatures
http://www.eudesign.com/mnems/startemp.htm
http://www.geocities.com/SummerDale33/Mnemonic.html
Star
Type
O
B
A
F
OUR
G
SUN
K
M
K
Temperature
◦C
◦F
> 25,000
> 24,727
> 44,540
11,000 – 25,000
10,727 – 24,727
19,340 – 44,540
7,500 – 11,000
7,227 – 10,727
13,040 – 19,340
6,000 – 7,500
5,727 – 7,227
10.340 – 13,040
5,000 – 6,000
4,727 – 5,727
8,540 – 10,340
3,500 – 5,000
3,227 – 4,727
5,840 – 8,540
< 3,500
< 3,227
< 5,840
Color
blue
blue
white
yellow
yellow
red
red
II. Magnitude: star’s brightness (luminosity)

Absolute Magnitude



The actual brightness of a
star
How bright it IS
Apparent Magnitude


The brightness of a star as
viewed from Earth
How bright it SEEMS
Distance
Size
Temperature
Two astronomers discovered a relationship between
the absolute magnitude (real brightness) of a star and
its surface temperature. They plotted the data on a
graph.
Ejnar Hertzsprung
Denmark
Henry Russell
USA
H-R Diagram
--illustrates the relationship that exists
between the average surface temperature
of stars and their absolute magnitude.
As absolute magnitude(brightness) increases,
surface temperature increases.
So what does this show?
Stars
seemed
to
naturally
group
together
They
discovered
that stars
grouped by
type and
during their
lifetimes would
move from one
place on the
graph to
another. As
our sun ages, it
will move to a
giant star to a
white dwarf.
Star Brightness vs Temperature
When a star forms it begins its “life.”
When a star runs out of fuel, it dies.
So a star has a life similar to a battery that cannot
be recharged. When the battery runs out of energy,
it is finished. Our sun will run out of energy and it
will be finished too. But this will not happen for
another 5 billion years!
Star Life Cycle
Star Life Cycle - unsequenced
Star Life Cycle - sequenced
Comparison of our sun with a white dwarf and a neutron
star.