Stars are hot balls of gas made primarily of hydrogen and helium. Astronomers classify stars based on characteristics like their age, color, brightness, temperature, and size to better understand the different types of stars. Key characteristics include a star's luminosity or brightness, temperature which determines its color, possible sizes ranging from dwarf to supergiant, and spectral class which is determined by temperature and color.

1. By Kara MacDevitt
International High School at Lafayette
CHARACTERISTICS OF STARS

2. A STAR
• Stars are hot, glowing balls of gas.
• They are made of the gases hydrogen (H) and helium
(He).
• Astronomers classify stars based on their age, color,
and brightness. These characteristics help them
identify and understand the different kinds of stars.

3. LUMINOSITY
• Also known as Magnitude or brightness.
• Depends on size and temperature.
• This is how much light a star gives off.
• Stars can be bright (1,000,000) or dim (0.0001)
• Bright Dim

4. TEMPERATURE
• The temperature of a star – hot (30,000 degrees K) or
cool (3,000 degrees K)
• Temperature determines color of a star
(hot – blue and cool – red)

5. SIZE
• Stars all look the same size, but they are not.
SIZES of STARS:
• Small, medium or LARGE
• dwarf, medium,Giant or SUPER GIANT

6. COLOR & SPECTRAL CLASS
• Spectral class is a letter that is determined by the
temperature and color of a star.
• 7 Colors
• 7 Spectral Classes

7. TYPES
• Star types are determined by luminosity and
temperature.
Types:
Super Giants
Giants
Main Sequence
Dwarfs