1. Classifying stars!

2. What IS a star anyway?!?!
STARS:
A star is a large ball of
ionized gas, held together by
gravity, that emits energy
produced by nuclear
reactions in its interior.
Types of stars:
 Stars are classified by
their size,
temperature, and
brightness!

3. Classifying Stars
SIZE!!!!
Temperature!!!
 Super Giant
 Hot = Red
 Red Giant
 Hotter = White
 Main
 Hottest = Blue/White
Sequence
 White Dwarf
 Neutron Star
Brightness!
 How bright it appears
depends on it’s distance
from us
 How bright it actually is
depends on its size & temp.

4. Relationship between surface temperature
and color of stars:
3,500 K
(red)
5,000 K
(yellow)
Just like car headlights
look small and dim
when they are far away
and then BLIND you as
they get closer, Stars
are similar.
7,000 K
(white)
25,000 K
(blue)
You may notice at night
when you look up at the
stars that some seem
to be slightly different
colors, that has to do
with their temperature!

5. Apparent vs. Absolute
Apparent Magnitude
 The observed
luminosity of a celestial
body, such as a star, as
observed from earth.
 The apparent
magnitude of a star
depends on its
luminosity and
distance.
Absolute Magnitude
 The apparent
magnitude a star
would have if it were
32.6 light years away
from Earth.

6. TOOLS OF ASTRONOMY
Spectrograph: A tool that is used to obtain
information from stars by breaking up the colors
they emit.
http://herschel.jpl.nasa.gov/farIRandSubmm.shtml

7. Chemical
compositions:
Each element absorbs different
wavelengths of light and shows
up as lines on a spectrum.

8. Temperature: Stars at
different temperatures
produce a different line
spectra.

9. Distances to stars
•Light Speed: Light travels
at 300,000 km/s.
•Light Year: The distance
light travels in a year.