DVD Table of Contents
Educator's Index
Neutron Stars in Binary Systems

Eclipsing Binary Light Curves

HT Cas data from ASCA

Here are part of the X-ray data from observations of HT Cas. Although a lot noisier than the sample binary data, you can still see the general shape of the curve and how the X-ray intensity drops as the X-ray emitting star is eclipsed by the central star. It might be easier to print out this page and measure from the printed version, rather than from the screen.

The orbital velocity of the secondary star in the HT Cas system is 28500 km/min. For this problem, the change in time (Δt) will not be a whole number, e.g., '3.2' but not '3'. Using this information and the ASCA light curve above, calculate the size of the central star.

HINT: distance as function of time and

Warning: Do not type a comma in your answer!

The diameter of the central star in HT Cas is: km