When studying a star like Betelgeuse, it is indeed possible to detect changes in its composition over time, particularly as heavier elements are created within its core through nuclear fusion processes. However, it's important to note that directly observing the internal composition of a star is challenging, as we primarily rely on indirect methods and observational data to infer its properties.
One way to analyze the composition of a star is through spectroscopy. By splitting the starlight into its constituent wavelengths, astronomers can identify the specific absorption and emission lines produced by different elements. Each element has a unique spectral fingerprint, allowing us to determine which elements are present and in what quantities. Spectral lines provide information about the outer layers of a star, including its surface temperature, atmospheric composition, and abundance of certain elements.
To study the interior composition of a star, scientists rely on stellar models and theoretical calculations. These models take into account factors such as mass, temperature, pressure, and fusion reactions to simulate the life cycle of a star and predict the changes in its composition over time. These models help us understand the progression of nuclear reactions within a star, from the fusion of lighter elements like hydrogen into helium, to the synthesis of progressively heavier elements.
Observationally, certain types of stars, such as red giants like Betelgeuse, exhibit pulsations or variability in their brightness. By studying these variations and analyzing the star's light curve, astronomers can gather information about its internal structure and composition. Variations in brightness can indicate changes in the fusion processes and the movement of energy through different layers of the star.
Additionally, when massive stars near the end of their lives go supernova, the explosion releases a tremendous amount of energy and ejects material into space. By studying the light emitted by these supernovae, astronomers can analyze the elemental composition of the ejected material, which provides insights into the composition of the parent star.
In summary, while directly observing the internal composition of a star like Betelgeuse is challenging, astronomers can infer changes in its composition through spectroscopy, theoretical models, and observations of stellar properties and events. These methods allow us to gain valuable insights into the evolution and life cycles of stars.