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Stars Still Make Them!

Understanding nuclear fusion in stars continues to be difficult. Scientists still struggle, even after hundreds of years of observations.  Add to that the fact that the Sun has been much too bright to study directly with telescopes, and it has been a very long road to understanding our closest star. However, based on initial observations, the technology that is continuously improving has allowed us to make models of the sun and other stars. As we learn more and more, the evidence either supports our model or causes us to make changes.  There are some things, however, that have given great support to the ideas that we have discussed about nuclear fusion and heavy elements being produced inside stars.

First, the most recent discovery. Remember what happens during the fusion of hydrogen atoms to form helium? In the process of hydrogen fusing to form helium, neutrinos are formed. Astronomers are discovering how to detect the neutrinos they expect to see coming from stars during the nuclear fusion process.

Second, you have already seen the value of studying the spectral lines of an image. By looking at the red or the blue shift learned about earlier, we can tell if an object is moving toward or away from us. There is another use for studying spectral lines. As we have already stated, each element emits different wavelengths from others, and that light can be seen as spectral lines in a spectroscope. They serve as a "fingerprint" for that element. If we see the spectral lines from a certain element in a star, we know that the star contains that element. This is how we know that the nuclear fusion process described in the life cycle of stars really happens. We use the evidence gained from spectroscopes to build a model of the star. It is, obviously, impossible to go visit the sun, so we use other measures to discover how stars produce so much energy. Spectroscopes provide us with at least one way to know that stars produce the elements found on Earth.
Click here to view the “fingerprints” (emission spectra) for a few common elements.


  1. Which of the following elements' spectral lines would indicate that a star is forming heavy elements, as has been discussed?
    • Hydrogen
    • Mercury
    • Helium
    • Lithium
  2. A scientist observing a star looked at the spectral lines it emitted. Which of the elements would indicate the star is fairly young?
    • Uranium
    • Helium
    • Radon
    • Carbon
  3. Why do young stars generally produce lighter elements through nuclear fusion?

Check your answers.

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Updated October 24, 2008 by: Glen Westbroek

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