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

The image compares the arrangement of electrons in two different neutral atoms. a figure labeled atom q has a shaded sphere at the center of three concentric circles. the innermost circle has two black spheres. the middle circle has six black spheres. to the left of this figure is another figure labeled atom p. atom p has a shaded sphere at the center of three concentric circles. the innermost circle has two black spheres. the middle circle has seven black spheres. which of the following best explains the position of the two atoms in the periodic table? atom p has an estimated zeff of 7 and is therefore to the left of atom q, which has a zeff of 6. atom p has an estimated zeff of 7 and is therefore to the right of atom q, which has a zeff of 6. atom p has an estimated zeff of 5 and is therefore below atom q, which has a zeff of 4. atom p has an estimated zeff of 5 and is therefore above atom q, which has a zeff of 4.