close to the value 1 with a very small error and is not correlated with the other parameters so we fix this parameter at 1 for the analysis presented here.

The aim of this analysis is to characterise each binary system in order to identify systems of interest for further study and for comparison to binary population models. The parameters we have derived are reliable enough for this purpose but further work is needed to determine the accuracy of these parameters. The K2 data clearly have the potential to produce very precise parameters for some binary systems, but we have not attempted to characterise the level of systematic error in these parameters for all the systems studied. We advise that a careful study of these issues should be done before the parameters of individual binary systems are used to test stellar evolution models.

Effective temperature estimates\[TeffSection\]
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We have used empirical colour – effective temperature and colour – surface brightness relations to estimate the effective temperatures of the individual stars in the binary and triple systems we have studied. We extracted photometry for each target from the following catalogues – B$_{\rm T}$ and V$_{\rm T}$ magnitudes from the Tycho-2 catalogue 