GENERAL KNOWLEDGE

Detailed explanation-1: -From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving. We can learn about winds in stars from this.

Detailed explanation-2: -The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy. Today, this process uses instruments with a grating that spreads out the light from an object by wavelength. This spread-out light is called a spectrum.

Detailed explanation-3: -Astronomers use spectrographs attached to telescopes to view the spectral lines of stars and other celestial objects. A spectrograph combines either a prism or diffraction grating to spread the light from a source into its spectrum. It then has a detector, usually a CCD, to record the spectrum.

Detailed explanation-4: -Astronomers are able to measure the temperatures of the surfaces of stars by comparing their spectra to the spectrum of a black body. A black body is one that entirely absorbs all radiation that strikes it. Astronomers determine the black body spectrum which most closely matches the spectrum of the star in question.