1. Stars

2. Star Classification Stars are classified using 3 main characteristics:
Size
Temperature
Brightness

3. Size Neutron Stars the smallest about 20 km. in diameter
Ex. Crab Nebula

4. Size
White Dwarf
about the size of Earth
D = ~ 14,000 km.
Ex. Sirius B

5. Size
Medium-Sized
made mostly of hydrogen at very high temperatures (5,500 oC) and pressures
Made of plasma
D= ~1.4 million km.
Ex. the Sun

6. Size Giant Supergiant very large stars D = 14-140 million km.
Ex. Aldebaran
Supergiant
the largest of stars
- D = million km.
Ex. Betelgeuse

7. Temperature
The temperature of a star is indicated by the color it glows.
Type of Star
Color
Surface Temp (oC) O
Blue
Above 25,000 B
Blue-White
10,000 – 25,000 A
White
7,500 – 10,000 F
Yellow-White
6,000 – 7,500 G
Yellow
5,000 – 6,000 K
Orange
3,500 – 5,000 M
Red
Below 3,500

8. Brightness
Brightness of a star depends on its size, temperature, and its distance from Earth.
-- Apparent magnitude:
A star’s brightness as seen from Earth
Measured with electronic devices
--Absolute magnitude
The brightness the star would have if it were at a standard distance from Earth