Star Spectra

Spectra of Stars
photo by Joseph Behum

This 10-minute exposure of the constellation Aurigia was photographed through a glass prism onto ASA 400 color film using a 50 mm lens at f/2.8.  Notice each star appears as a colored streak, with the red portion to the left and the blue portion to the right.  Differences between the physical properties of the stars can be determined by analyzing their spectra.

Image of the stars in the constellation Orion photographed through a prism by Samantha Beard on the night of 12 April 2009. The photograph was made on a Canon EOS 10D digital camera using a 28 mm lens set at f/2.8 for this 30 second exposure at an ISO setting of 400.

This trailed star image is actually 5 separate exposures of 30 seconds each, photographed through a prism placed in front of the objective lens of a Canon EOS 10D digital camera by Samantha Beard during the evening of 12 April 2009. The stars are within the constellation Orion. The 28 mm camera lens was set to an f/2.8 focal ratio, and the sensitivity of the camera was set to ISO 400. The stationary camera was oriented for the stars to trail in a direction perpendicular to the direction of dispersion of the light in each spectrum.

Defocused star images in Orion, by Samantha Beard, during the evening of 21 March 2009. The image was made by a stationary Canon EOS 10D digital camera using a 28 mm objective lens set at f/2.8 and a camera setting of ISO 400. The image shows 12 separate exposures of 30 seconds each, with some manual defocusing of the objective lens between each of the 12 exposures. The color of the stars is difficult to determine both where the light is too bright and where it is too faint, but between these extremes the light will have the appropriate intensity for the color of each star to be most evident.