Effective temperature and the light curve solution of contact binary systems

SUMMARY: With an increasing number of contact binary discoveries and the recognition that luminous red novae are the result of contact binary merger events, there has been a significant increase in the number of light curve solutions appearing in the literature. One key element of such solutions is assigning and fixing the effective temperature of the primary component (T1). Sometimes the expectation that the assigned temperature will significantly alter light curve solution is exaggerated even though theoretical considerations suggest that the absolute value of T1 has little influence on the geometric elements of the light curve solution. In this study, we show that assigning T1 over a range of 1000 K has no significant influence on the light curve solutions of two extreme low mass ratio contact binary systems. In addition, we explore the use of photometric spectral energy distribution as a potential standard for assigning T1 in the absence of spectroscopic observations.