Into The Stars
An analysis of the makeup of stars By Lara, Emily, and Kai
How are elements in stars identified?
Elements are identified using the technique of spectroscopy. Spectroscopy is the analysis of radiation. As electrons move to lower energy levels, radiation is emitted at a certain wavelength. Each element has its own unique wavelength, allowing scientists to easily identify them. Bright line spectra are used to identify elements.
Hand-Held Spectroscope
This spectroscope reveals the hidden nature of color and visible light with this durably constructed, economical spectroscope.
Analysis of a Star
Astronomers pass starlight into a spectroscope to discover what elements are in each star. Each element gives off a unique pattern of colors, allowing scientists to easily differentiate what elements are in what star.
Spectroscope
This type of direct vision spectroscope was first introduced by Hofmann in 1862. It utilizes a series of five prisms cemented together consisting of two different types of glass (crown and flint) having differing indices of refraction. (Hoffman, Spectroscope).
What are stars made up of?
- approximately 71% Hydrogen
- approximately 27% Helium
- less than 2% of other elements such as Carbon, Oxygen, Nitrogen, Lithium, etc.
Hydrogen Absorption Spectrum
Hydrogen will absorb different energies from Helium and they will only absorb photons with exactly the right energy of 1216x10^-10 meters.
Helium Absorption Spectrum
The allowed energy levels in an atom depend on the electric field configuration. Helium contains 2 protons, which is why it has a different energy level and different characteristic absorption lines.
Carbon Absorption Spectrum
Carbon atoms do not absorb infrared light frequencies because there is a methyl at each end of the bond. However, the C-H bonds within the methyl groups do absorb light.
Oxygen Absorption Spectrum
Peaks and dips at specific points in a spectrum indicate the presence of elements such as Oxygen. Oxygen is found in the core of many stars.
Nitrogen Absorption Spectrum
It is known that symmetrical diatomic molecules like Nitrogen do not absorb infrared radiation.
Lithium Absorption Spectrum
Lithium is depleted in stars as they age. Convection mixes the material and transports it between the star's surface and interior. This process of convective mixing reduces the surface amount of lithium. Scientists can then see lithium absorption lines to help identify the lithium in the star and the age of the star.