Astronomers study the spectrum of a distant star and observe strong absorption lines at 1.4µm (water vapor) and 2.3µm (methane). What can they conclude about this star?
Answer
A
The star is fusing hydrogen into helium.
B
The star's atmosphere is too hot for other molecules to exist.
C
The star's atmosphere contains water vapor and methane.
D
The star is primarily composed of hydrogen.
Explanation
Absorption lines occur when substances in a star’s atmosphere absorb light at specific wavelengths. Lines identified as water vapor at 1.4 µm and methane at 2.3 µm therefore indicate that the atmosphere contains water vapor and methane.
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