The Triple Eccentric Systems V974 Cyg, RU Mon, and V456 Oph
M. Wolf1, P. Zasche1, H. Kučáková1,2,
K. Hoňková2, J. Juryšek2,3,
M. Mašek2,3, R. Uhlař2,4
and M. Urbaník5
1Astronomical Institute, Faculty of Mathematics and Physics, Charles University, CZ-180 00 Praha 8,
V Holešovičkách 2, Czech Republic
e-mail: wolf@cesnet.cz
2Variable Star and Exoplanet Section, Czech Astronomical Society
3Institute of Physics, Czech Academy of Sciences, Na Slovance 1999/2, CZ-182 21 Praha 8, Czech Republic
4Private Observatory, Pohoří 71, CZ-254 01 Jílove u Prahy, Czech Republic
5Kysuce Observatory, Dolinský potok 1278, SK-024 01 Kysucké Nové Mesto, Slovakia
Received: April 10, 2017
ABSTRACT
We present results of a long-term program for timing the eclipses of
eccentric eclipsing binaries. About 40 new precise mid-eclipse times
were measured for the eclipsing binary V974 Cyg, RU Mon and
V456 Oph. Based on current O-C diagrams, we found in all cases
that times of minima besides the typical apsidal motion show
additional cyclical changes caused very probably by the third bodies
orbiting the eclipsing pair. The periods of apsidal motion are
1470 yr, 361 yr and 22.6 yr, respectively. The period
of V456 Oph this is one of the shortest known apsidal-motion
periods. The relativistic contributions to the total apsidal-motion
rate are significant for V974 Cyg (about 30%) and negligible
for RU Mon and V456 Oph (1-2.5%). The third-body orbital
periods are relatively short: 30.6 yr, 59.8 yr and
7.4 yr, and their minimal masses are
0.40 M☉, 1.6 M☉, and
0.27 M☉, respectively.
Key words:
binaries: eclipsing - Stars: individual: V974 Cyg, RU Mon, V456 Oph -
Stars: fundamental parameters
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