Question

If two stars, X and Y, are the same size, but star X has a spectrum that peaks at a shorter wavelength than star Y, what can we conclude about them?

a) star X is cooler than star Y
b) star X emits less red light than star Y
c) star X is brighter than star Y
d) star X has fewer sunspots than star Y
e) star X would appear white

Answer 1

Star X is hotter than star Y because it emits light at a shorter wavelength, corresponding with its spectrum peaking at the blue end, which indicates a higher surface temperature.

Step-by-step explanation:

If two stars, X and Y, are the same size, but star X has a spectrum that peaks at a shorter wavelength than star Y, we can conclude that star X is hotter than star Y. This conclusion is supported by Wiens law, which relates stellar color to stellar temperature, indicating that stars emitting light at shorter wavelengths are hotter.

The color of light that dominates a star's appearance provides a rough indicator of its temperature, with blue being a sign of a hotter star, and red indicating a cooler star.

A shorter wavelength in the spectrum corresponds to higher energy photons and therefore a higher surface temperature. Since star X emits at a shorter wavelength compared to star Y, it is emitting light that is more towards the blue end of the spectrum, which is characteristic of a hotter star. Therefore, the correct answer to the student's question is that star X is hotter than star Y, even though this was not one of the exact options provided.