Journey into Spectroscopy
Date
2001
Authors
University of Texas at Austin
McDonald Observatory
Journal Title
Journal ISSN
Volume Title
Publisher
McDonald Observatory
Abstract
Department
Description
Introduction: Astronomy fundamentally changed after Henry Draper
first photographed the spectrum of the star Vega in 1872.
Soon thereafter, astronomers began surveying the stars
and photographing their spectra. The resulting flood of
stellar spectra was a blessing and a challenge. The bewildering
variety of stellar spectra demanded a simple, adaptable,
and meaningful organization system. By 1924, Annie
Jump Cannon had revised the stellar spectra organization
system and personally classified over two hundred thousand
stars. Her basic system is still in use today.
In this activity, students begin their exploration by following
in Cannon’s footsteps to organize a few stellar
spectra. Later they learn that the absorption features in
the spectrum change according to the temperature of the
star. Given this information, they may revise their organization
scheme and order the stars by temperature. In this
way, they come to understand the code for temperature
in a star’s spectrum. In the explanation section, students
learn the history of how Cannon and others dealt with
this same problem