The Colorful Stars: Sun vs Rigel

How does the spectral curve of the Sun compare to Rigel?

A. cooler and redder.B. cooler and bluer.C. hotter and redder.D. hotter and bluer.

Answer:

Rigel, with a spectral curve peaking in the short-wavelength end of the visible spectrum, is hotter and bluer compared to the Sun.

The Sun's spectral curve peaks in the yellow-green region of the spectrum, making this region the most intense part of its spectrum. On the other hand, the spectrum of Rigel, the star in the knee of Orion, peaks in the short-wavelength end of the visible spectrum.

The peak wavelength of a star's spectrum is indicative of its temperature and color. In the case of Rigel, which has a peak at the short-wavelength end of the visible spectrum, it signifies a high surface temperature. Shorter wavelengths correspond to the blue end of the spectrum, so Rigel's spectral curve being shifted towards these shorter wavelengths compared to the Sun indicates that Rigel is both hotter and has a bluer color than the Sun.

Therefore, Rigel is hotter and bluer when compared to the Sun. This conclusion is based on the principle that as temperature increases, the peak wavelength shifts towards shorter, bluer wavelengths. The Sun, with a peak at 0.5µm in the yellow-green region, is cooler than Rigel, whose spectrum peaks even shorter than visible light, signifying temperatures much hotter than the Sun's 5800K.