What is the significance of measuring the spectral lines of a star?

Measuring the spectral lines of a star is crucial because it provides significant information about the star's composition and temperature. Each element emits or absorbs light at specific wavelengths, creating unique spectral lines. By analyzing these lines, astronomers can identify which elements are present in the star's atmosphere. This analysis reveals important details about the star's chemical makeup, including the abundance of elements such as hydrogen, helium, and heavier metals.

Additionally, the width and shape of the spectral lines can indicate the temperature of the star. Hotter stars produce lines that may be broader or shifted due to different physical processes occurring at higher temperatures. This relationship between temperature and spectral lines allows astronomers to classify stars and understand their evolutionary stages more effectively.

The other options, while related to astrophysical concepts, do not accurately reflect the significance of spectral line measurement. For instance, the determination of a star's distance is often done through methods such as parallax, not through spectral lines alone. Similarly, a star's lifetime and its gravitational influence on nearby planets involve different aspects of stellar astrophysics and dynamics that are not directly derived from the analysis of spectral lines.