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Required Windows Software

The HR Diagram exercise utilizes the Virtual Educational Observatory Software, Click Filename to Download (using left mouse button to "Save Link As") This is a self-extracting file and will install itself when you run it on your computer. But beware: THE PROGRAM IS VERY LARGE, 230 MEGABYTES, SO ONLY DOWNLOAD IF YOU HAVE A VERY FAST CONNECTION!! Otherwise, see below---we are happy to send you a free copy.

If you would prefer to receive the software on disk: We will be happy to send you the VIREO software at no cost on a CDRom. Contact us by clicking the link below.

You will also need the manual---downloadable from the link below: take a look and see what the exercise entails!

Student manual (MS Word format)

A Description of the Lab: 
Purpose: To illustrate how HR diagrams of star clusters are used to determine the distances and ages of the clusters. If desired, students can also measure the magnitudes and colors of the cluster stars using a simulated telescope, thus learning how astronomers collect the data used to produce an HR diagram.

H-R Diagrams of Star Clusters, is the first in a series of exercises using its Virtual Educational Observatory (VIREO). Using real photometric data from a variety of sources, students are able to access databases of V magnitudes and B-V colors, as well as positions for stars in a variety of clusters of differing ages and distances. Students can load this data directly into display software, and can view the clusters in the VIREO optical telescope. They can, if desired, measure the apparent magnitudes of the stars themselves using simulated telescopes equipped with photometers and CCD Cameras, and store the data for later analysis. Data analysis software, which draws on an extensive database of theoretical isochrones, allows students to fit HR diagrams to models. Students are thus able to determine distance modulus, reddening, and ages of the clusters. The exercise includes a student workbook with brief background information on stellar evolution, along with instructions on the use of the software.


Overview of Software CLEA Home Page