The interval between two notes (one higher than the other) of the same name that have a similar sound because the upper has exactly double the sound vibrations per second of the lower is called a/an

The rocks expand when there hot/warm  and contract when they are cold.

We can infer that star y is closer but other factors must be considered include the heat of the star, the mass, and the brightness of the star. even though star x seems dimmer it may just be less bright or contains less heat.