The Late K-type Binary V1104 Her Near the Short-period End of Contact Binaries

V1104 Her is a newly discovered periodic variable with EW type variability. With an orbital period that is extremely short for a contact binary, it was found to have almost the latest K spectral type. To study its properties and nature, two new sets of multi-color light curves were analyzed with the Wilson-Devinney code. Photometric solutions reveal that the system is a W-type shallow contact binary with a mass ratio of 1/q=M-1/M-2=0.63. +/- 0.01 and a degree of contact of about f=15% +/- 2%. The real parameter uncertainties may be from three to five times larger, depending on the required confidence. Combining the newly determined times of minimum light, some of which were reprocessed from initial data, in conjunction with others published, the period variation is investigated in detail. Different methods of curve fitting were used, based on a weighted least-squares method. Finally, the orbital period of V1104 Her is found to be undergoing a long-term decrease at a rate of dP/dt = -2.9(+/- 0.5) x 10(-8) days . yr(-1), as well as double cyclic oscillations with a period ratio (T-1/T-2) very close to 9:2. The light-travel time effect was found to be the best explanation for the cyclic variations. This indicates that the object is a possible quadruple system, which further implies that multiplicity may be a common phenomenon among close binaries.