1. STARS

2. There are MORE than
200 billion, billion stars in a universe. Most stars contain mainly hydrogen and helium.

3. Color of a star: tells what the surface temperature of the star is
HOTTEST STAR: shines with a
blue-white light
COOLEST STAR: shines with a red light

4. Star Temperatures http://www. eudesign. com/mnems/startemp
Star Type
Temperature
Color K ◦C ◦F O
> 25,000
> 24,727
> 44,540
blue B
11,000 – 25,000
10,727 – 24,727
19,340 – 44,540 A
7,500 – 11,000
7,227 – 10,727
13,040 – 19,340
white F
6,000 – 7,500
5,727 – 7,227
– 13,040
yellow G
5,000 – 6,000
4,727 – 5,727
8,540 – 10,340
3,500 – 5,000
3,227 – 4,727
5,840 – 8,540
red M
< 3,500
< 3,227
< 5,840
OUR
SUN

5. Absolute Magnitude Apparent Magnitude
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

6. Apparent magnitude affected by:
Distance
Size
Temperature

7. 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.

8. Star Brightness vs Temperature