Aims: We present the detailed analysis of triple system KR Com with different
observational techniques - photometry, interferometry, and period variation.
Methods: The use of BVR photometry of the close-contact binary KR Com, which is
the primary component of a triple system, helps us to better describe the
properties of the components. The interferometric data obtained during the last
30 years sufficiently determine the visual orbit, but the use of minima timings
of KR Com for the study of period variation together with the visual orbit is a
novel approach in this system. Results: Basic physical parameters resulting
from the light curve analysis agree well with the previous results from
spectroscopy. The temperatures for the primary and secondary component resulted
in 5549 and 6072 K, respectively, and the amount of the third light in all
filters is about 1/3 of the total luminosity. The distant third component
revolves around the common barycenter on 11 yr orbit with a very high
eccentricity (0.934) and this movement is also detectable via the period
variation, which is clearly visible in the O-C diagram of times of minima
observations. The use of minima times for the combined analysis helps us to
independently determine the distance to the system (64.02 +/- 9.42 pc) and also
to confirm the orientation of the orbit in space. Conclusions: New minima
observations and also spectroscopy would be very profitable, especially during
the next periastron passage in the year 2017.Comment: 7 pages, 7 figures, published in 2010A&A...519A..78