Question

The Sun's spectral curve peaks in the yellow-green region of the spectrum (i.e., this region is the most intense part of its spectrum). The spectrum of Rigel (the star in the knee of Orion) peaks in the short-wavelength end of the visible spectrum. Compared to the Sun, Rigel isSelect one:A. cooler and redder.B. cooler and bluer.C. hotter and redder.D. hotter and bluer.

Answer 1

Answer: D. hotter and bluer.

Explanation:

The color temperature of a light source (a bulb or a star, for example) is defined by comparing its color within the electromagnetic spectrum with that of the light emitted by a black body ("a theoretical or ideal object that absorbs all the light and all the radiant energy that falls on it") heated to a certain temperature (expressed in Kelvin).

Then, according to this, a black body with a temperature of 800K will emit its light in red and one at 12200K will emit its light in blue. This means that as the body heats up it will change its color.

In the case of stars, such as Rigel and the Sun, their color varies according to their surface temperature, where the coldest stars are red, and the hottest blue colors.

So, if Rigel's spectrum peaks in the short-wavelength end of the visible spectrum (violet-blue) and Sun's spectrum peaks in the yellow-green region of the visible spectrum, this only means:

Compared to the Sun, Rigel is hotter and bluer.