Astronomy: Types of Stars: Color, Size, and Temperature Worksheet

Question 1

Put these star colors in order from coolest surface temperature to hottest surface temperature: blue, red, yellow, white.

Accepted Answer

The order from coolest to hottest is red, yellow, white, and blue. Red stars have the coolest surfaces, while blue stars have the hottest surfaces.

Question 2

A star appears red-orange in color. What does this suggest about its surface temperature compared with a blue-white star?

Accepted Answer

A red-orange star has a cooler surface temperature than a blue-white star. Blue-white stars are among the hottest stars.

Question 3

The Sun is a yellow main sequence star. What does its yellow color tell scientists about its surface temperature?

Accepted Answer

The Sun's yellow color tells scientists that its surface temperature is in the middle range for stars. It is hotter than red stars but cooler than white and blue stars.

Question 4

Describe the difference between a main sequence star and a red giant.

Accepted Answer

A main sequence star is a stable star that is fusing hydrogen in its core. A red giant is a later stage star that has expanded to a very large size and has a cooler outer surface.

Question 5

A star is very large, bright, and blue. What can you infer about its temperature and energy output?

Accepted Answer

A very large, bright, blue star is extremely hot and gives off a large amount of energy. It is likely much hotter and more luminous than the Sun.

Question 6

Two stars are the same temperature, but Star A is much larger than Star B. Which star is likely more luminous, and why?

Accepted Answer

Star A is likely more luminous because it has a larger surface area. If two stars have the same temperature, the larger star gives off more total light.

Question 7

Complete the comparison: A white dwarf is usually small and hot, while a red supergiant is usually ____ and ____.

Accepted Answer

A red supergiant is usually very large and relatively cool at its surface. Its red color shows a cooler surface, and its name shows it is enormous.

Question 8

Explain why star color is a useful clue for classifying stars.

Accepted Answer

Star color is useful because it gives information about a star's surface temperature. Scientists can use color along with brightness and size to classify stars.

Question 9

A Hertzsprung-Russell diagram shows temperature from hot on the left to cool on the right, and luminosity from dim at the bottom to bright at the top. Where would you expect to find hot, bright blue stars?

Accepted Answer

Hot, bright blue stars would be found near the upper left of the diagram. They are hot, so they belong on the left, and they are bright, so they belong near the top.

Question 10

Where would you expect to find cool, dim red dwarf stars on a Hertzsprung-Russell diagram?

Accepted Answer

Cool, dim red dwarf stars would be found near the lower right of the diagram. They are cool, so they are on the right, and they are dim, so they are near the bottom.

Question 11

A student says, "All red stars are small." Explain why this statement is incorrect.

Accepted Answer

The statement is incorrect because red stars can have different sizes. Red dwarfs are small, but red giants and red supergiants are very large.

Question 12

Match each star type with the best description: red dwarf, blue supergiant, white dwarf, red giant. Descriptions: small and cool, very large and very hot, small and hot, very large and cool at the surface.

Accepted Answer

A red dwarf is small and cool. A blue supergiant is very large and very hot. A white dwarf is small and hot. A red giant is very large and cool at the surface.

Question 13

A star has a surface temperature of about 3,500 K and a reddish color. Another star has a surface temperature of about 10,000 K and a blue-white color. Which star is hotter, and how do you know?

Accepted Answer

The blue-white star is hotter because 10,000 K is a higher temperature than 3,500 K. Its blue-white color also matches a hotter surface temperature.

Question 14

Look at this imaginary set of stars: Star 1 is red and dim, Star 2 is yellow and medium-bright, Star 3 is blue and very bright. Rank them from coolest to hottest.

Accepted Answer

The stars ranked from coolest to hottest are Star 1, Star 2, and Star 3. Red stars are coolest, yellow stars are warmer, and blue stars are hottest.

Question 15

Explain how color, size, and temperature together can help astronomers understand what kind of star they are observing.

Accepted Answer

Color helps astronomers estimate surface temperature, size helps them compare how much light a star can produce, and temperature helps classify the star. Together, these properties can show whether a star is a red dwarf, main sequence star, giant, supergiant, or white dwarf.

Astronomy: Types of Stars: Color, Size, and Temperature

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