Work Step by Step
Figure 30.7 shows the radiation curve of an incandescent source. It spans a broad band of frequencies. A star that you see as red-hot must have its peak frequency in the infrared, with some emitted light in the lower-frequency (red) part of the visible spectrum. If the star were any hotter, with its peak frequency in the red range, it would emit significant light in all parts of the visible spectrum, and appear to be white, not red.