Stars are large balls of ionized gas held together by gravity that emit energy through nuclear reactions. They are classified by size, temperature, and brightness. Size categories include super giants, red giants, and main sequence stars. Temperature determines color, from red (coolest) to blue-white (hottest). Brightness depends on a star's luminosity and distance, though tools like spectroscopy can provide more information about chemical compositions and temperatures to help understand stars.

1. Stars! I’m seeing 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
Brightness!
 White Dwarf
 How bright it appears
 Neutron Star
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 5,000 K 7,000 K 25,000 K
(red) (yellow) (white) (blue)
Just like car headlights You may notice at night
look small and dim when you look up at the
when they are far away stars that some seem
and then BLIND you as to be slightly different
they get closer, Stars colors, that has to do
are similar. with their temperature!

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

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.