Spectral Analysis of Stars Astronomy Spectral Analysis of Stars Lab 8-7 Pages 341-346

Energy Through Space Energy is transmitted through space as electromagnetic waves. The movement of these waves through space supports the concept of the ‘Big Bang’ ~ particles are still moving as a result of a gigantic explosion from a small, concentrated area.

Electromagnetic Spectrum: The arrangement of visible light by wavelength. (ROYGBIV) Angstrom: Very small measurement used to measure the distance between wavelengths of EM radiation.

Radial Velocity: The speed of a wavelength toward or away from radar. Doppler Shift: Change in frequency toward or away from an object. [Red shift is away and blue shift is toward]

Radiation: The transfer of energy by waves. Absorption Spectrum: Spectrum of light waves as they are received. (What we see) Radiation Spectrum: Spectrum of light waves as they are transmitted. Vacuum: An area with little or no pressure (outer space). Wavelength: Distance between wave crests. Frequency: Number of cycles that pass in a specific period of time. Lambda: The frequency of a wavelength

Spectral Periodic Table

What elements are in that star? We can determine which elements are found in distant stars by using a spectroscope to observe the wavelengths of energy being transmitted from the star.

For example . . . Each element emits a unique wavelength of light. The colors of the spectrum from long wave to short wave are: Red, Orange, Yellow, Green, Blue, Indigo and Violet [ROYGBIV] Long = Red Short = Violet

Different light = Different spectrum A light bulb will emit all the colors of the spectrum, whereas gas tubes will only emit the spectra of the specific element. Elements can be identified by their unique, characteristic spectra.

As the frequency of electromagnetic waves increases, the wavelength decreases. [Inverse relationship] The width of the visible light spectrum is a very small portion of the total spectrum.

As we move across the spectrum from gamma rays (short waves) to radio (long waves), wavelength increases and frequency decreases. Therefore, infrared waves are longer than visible waves.

Balmer Absorption Lines Balmer Absorption lines are the accepted values for spectral wavelengths. We can determine the radial velocity and direction of wavelengths by comparing them to the Balmer lines.

Spectral analysis determines several star features: Composition; Determined by distinguishing the elements found within the star by assessing the emitted wavelengths. Radial Velocity; difference between actual and accepted (Balmer) wavelength value x speed of light divided by the accepted (Balmer) value. Direction of movement; Red shift/away or blue shift/toward.