Practice using the stellar spectral classification sequence from hottest to coolest and connect each class to temperature, color, and examples of stars.
Read each problem carefully. Use the spectral class sequence O, B, A, F, G, K, M from hottest to coolest. Show your reasoning when asked.
Practice ordering O, B, A, F, G, K, and M stars by temperature and color
Astronomy - Grade 9-12
- 1
Write the stellar spectral classification sequence from hottest to coolest.
- 2
Put these spectral classes in order from hottest to coolest: K, A, O, G, M.
- 3
Put these spectral classes in order from coolest to hottest: B, F, M, K, O.
- 4
A star is classified as spectral type A. Another star is classified as spectral type K. Which star has the higher surface temperature, and why?
- 5
A diagram shows four stars labeled B, G, M, and F. Rank the stars from highest surface temperature to lowest surface temperature.
- 6
Match each spectral class to its most typical visible color: O, A, G, M. Use the choices blue, white, yellow, and red.
- 7
The Sun has spectral class G2. Based on its class, is the Sun hotter than a K star or cooler than a K star? Explain.
- 8
A star has a surface temperature of about 30,000 K. Another star has a surface temperature of about 3,500 K. Which one is more likely to be an O or B star, and which one is more likely to be an M star?
- 9
A student says, "Red stars are hotter than blue stars because red looks like fire." Correct the student's statement using stellar spectral classification.
- 10
Use the simplified H-R diagram idea that temperature increases to the left. If spectral classes are shown along the bottom from left to right, what order should they appear in?
- 11
Two stars are labeled F5 and F9. Within the same spectral class, lower numbers are hotter and higher numbers are cooler. Which star is hotter?
- 12
Rank these stars from hottest to coolest: A0, A9, B8, G2, M1, K5. Remember that the letter class matters first, and within a class, lower subtype numbers are hotter.