Harvard Classification Scheme Class

Color

Prominent spectral lines

Surface Temp. (K)

O

Blue

Ionized helium, hydrogen

> 25,000

B

Blue-white

Neutral helium, hydrogen

11,000 – 25,000

A

White

Hydrogen, ionized sodium, ionized calcium

7,500 – 11,000

F

White

Hydrogen, ionized sodium and calcium; neutral sodium and calcium

6,000 – 7,500

G

Yellow

Neutral sodium and calcium, ionized calcium, ionized iron, ionized magnesium

5,000 – 6,000

K

Orange

Neutral calcium, neutral iron, neutral magnesium

3,500 – 5,000

M

Red

Neutral iron, neutral magnesium, and neutral titanium oxide (not shown)

< 3,500

Use the Harvard Classification Scheme (shown in the table above) to answer the following quesiton: The Sun contains spectral lines from neutral sodium and calcium as well as ionized calcium, magnesium and iron. Of the choices below, which could be the surface temperature of the Sun?

4,200 K
5,800 K
8,900 K
14,300 K