Proyecto Astronómico Constelación Cruz del Sur southern_cross_colegio_cristobal_colon | Page 9

V. Classroom activity: Comparing stars.
How does the size of each star of the Southern Cross compare to the Sun? What happens if
its spectral class or absolute magnitude changes? We can work these questions with the
students in the classroom. In order to do this, we need a computer and the software H-R
calc6, about the Hertzprung-Russell diagram.
With data taken from the tables presented in this report (absolute magnitude and spectral
class) we can approximate the variety of star, size and temperature.
Steps:
a) Download the software from the Internet. Locate it using a search engine with
the terms “H-R Calc”.
b) Once downloaded and installed, we start the program, obtaining this screen:
c) Enter data for one the stars of the Southern Cross. You will get:
d) Obtain the position in the diagram and other information you require from the
software: