Read a Hertzsprung-Russell diagram
Grade 9 Science Worksheet
Circle the best answer.
A star is 4,500 K with a brightness of 100. Which kind of star is it, by Bo's reading?
- A giant: cool but bright
- A hot blue star, since it is bright
- A white dwarf
- A main-sequence star like the Sun
Read this first
Model stars (model data; Sun values from IAU)
Star Surface temperature (K) Brightness (Sun = 1) A 30,000 10,000 B 9,900 25 C (Sun) 5,800 1 D 3,500 0.01 E 3,600 100,000 G 20,000 0.01 Star A is 30,000 K with a brightness of 10,000. Which kind of star is it, by Esme's reading?
- A red dwarf
- A hot, blue main-sequence star
- A white dwarf, since it is hot
- A red supergiant
A star is 6,000 K with a brightness of 1.2. Where does it sit, by Jun's reading?
- On the main sequence, near the Sun
- Among the white dwarfs
- Among the blue stars, since 6,000 K is very hot
- Among the supergiants
Model stars (model data; Sun values from IAU)
Star Surface temperature (K) Brightness (Sun = 1) A 30,000 10,000 B 9,900 25 C (Sun) 5,800 1 D 3,500 0.01 E 3,600 100,000 G 20,000 0.01 Stars D (3,500 K) and E (3,600 K) have nearly the same temperature, but E is 10 million times brighter. Why, by Kira's reading?
- E is younger, earlier on its path
- E is far larger, with much more surface
- E is much hotter
- E is closer to Earth
Two stars have the same temperature, but one has twice the radius. How many times brighter is it (brightness grows as radius²), by Luz's math?
- 4 times
- The same, since temperature is the same
- 16 times
- 2 times
Two stars are the same size, but one is twice as hot (in kelvins). How many times brighter is it (brightness grows as temperature⁴), by Milo's math?
- 8 times
- 16 times
- 4 times
- 2 times
When the Sun leaves the main sequence, which way will its dot move, by Pia's reading?
- Up and to the left, toward the blue stars
- It stays in the same spot
- Down along the band to the red dwarfs
- Up and to the right, toward the giants
After its giant stage, the Sun becomes a white dwarf. Where will its dot be, by Ren's reading?
- Bottom left
- Top left
- Bottom right, since it will be dim
- Back on the main sequence
Model stars (model data; Sun values from IAU)
Star Surface temperature (K) Brightness (Sun = 1) A 30,000 10,000 B 9,900 25 C (Sun) 5,800 1 D 3,500 0.01 E 3,600 100,000 G 20,000 0.01 Star A has a brightness of 10,000 and Star B 25. How many times brighter is A, by Tala's math?
- 4,000 times
- 400 times
- 40 times
- 9,975 times
How many ×10 gridline steps is Star E (100,000) above the Sun (1), by Ari's count?
- 5 steps
- 100,000 steps
- 4 steps
- 50 steps
