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The light curve in Binary Maker plots the intensity of the binary against orbital phase. The orbital phase tells us how far through the orbit our measurement is and is given by: Orbital phase = (Ti - To)/period - integer part of ((Ti-To)/period) The orbital phase goes from 0 to 1 (where 1 is the same binary phase as 0). An orbital phase of 0.5 corresponds to halfway through the binary orbit, 0.75 is three-quarters the way through, and so on. Astronomers don't always see such nice, continuous data as the one plotted in our light curve. For example, we can only use optical telescopes during the night and this can range from 8 hours during the Summer to 12 hours during the Winter. If our binary star has an orbital period less than, say, 8 hours, then we will be able to observe one whole binary orbit or more. Otherwise we will only obtain data from part of the orbit. In the latter case the astronomer has to try and sample as many parts of the orbit as possible in order to discern the orbital period. If we have a set of discontinuous data in time we can "fold" the data on the orbital period. To do this we calculate the orbital phase for each measurement and plot the data as a function of orbital phase. It is much easier to see how the data vary over the binary orbit and, therefore, measure our binary parameters. |