How does the spectrum of a distant star reveal the star's chemical composition?

• A. By measuring the intensity of all wavelengths equally across the spectrum
• B. By displaying unique absorption lines corresponding to specific elements present in the star
• C. By indicating the star's temperature through the color of its spectrum
• D. By showing only the continuous spectrum emitted by the star's surface

Answer: (B)

Verified step by step guidance

1. Understand that a star's light, when passed through a prism or diffraction grating, produces a spectrum that can be analyzed.
2. Recognize that the star emits a continuous spectrum from its hot, dense interior, but its cooler outer layers absorb specific wavelengths of light.
3. These absorbed wavelengths appear as dark lines, called absorption lines, in the star's spectrum.
4. Each chemical element absorbs light at characteristic wavelengths, so the pattern of absorption lines acts like a fingerprint for the elements present in the star.
5. By comparing the observed absorption lines with known wavelengths of elements, scientists can determine the star's chemical composition.