KIC 9832227: using Vulcan data to negate the 2022 red nova merger prediction.
SOCIA Q.J., WELSH W.F., SHORT D.R., OROSZ J.A., ANGIONE R.J., WINDMILLER G., CALDWELL D.A. and BATALHA N.M.
Abstract (from CDS):
KIC 9832227 is a contact binary whose 11 hr orbital period is rapidly changing. Based on the apparent exponential decay of its period, the two stars were predicted to merge in early 2022 resulting in a rare red nova outburst. Fortunately KIC 9832227 was observed in 2003 as part of the NASA Ames pre-Kepler Vulcan Project to search for transiting exoplanets. We find that the Vulcan timing measurement does not agree with the previous exponential decay model. This led us to re-evaluate the other early epoch non-Kepler data sets, the Northern Sky Variability Survey (NSVS) and Wide Angle Search for Planets (WASP) survey. We find that the WASP times are in good agreement with the previous prediction, but the NSVS eclipse time differs by nearly an hour. The very large disagreement of the Vulcan and NSVS eclipse times with an exponentially decaying model forces us to reject the merger hypothesis. Although period variations are common in contact binaries, the physical cause of the period changes in KIC 9832227 remains unexplained; a third star scenario is unlikely. This study shows the data collected by the Vulcan photometer to be extremely valuable for extending the baseline for measurements of variable stars in the Kepler field.