417.04 KIC 9832227: a red nova precursor<br /> (Lawrence A. Molnar)

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Jan 7th at 2:40 PM until 2:50 PM

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Author(s): Lawrence A. Molnar2, Daniel Van Noord2, Karen Kinemuchi1, Jason P. Smolinski2, Cara E. Alexander2, Henry A. Kobulnicky3, Evan M. Cook2, Byoungchan Jang2, Steven D. Steenwyk2

Institution(s): 1. Apache Point Observatory, 2. Calvin College, 3. University of Wyoming

Molnar et al. (2015) suggested that KIC 9832227 is a contact binary star in its final years before merging and producing a red nova eruption. Analysis of light curves spanning 1999 to 2014 showed a negative time derivative and second derivative of the orbital period. The timing data were found to be well fit by the empirical exponential formula that Tylenda et al. (2011) used to describe preoutburst data of V1309 Sco. While it could not be concluded that this was the correct interpretation of the data, the prediction made for the near future was specific and falsifiable.

We will present light curve data from 2015-2016 which is consistent with the extrapolation of the previous fit. As predicted, the period derivative now exceeds the range measured for other contact systems. Reanalysis of the Kepler spacecraft timing data shows a low amplitude modulation consistent with a third star with an orbital period of 1.7 y and msin i = 0.11 solar masses. We will also present spectroscopic data that show the signature of both binary components. These data rule out the presence of any additional main sequence stars with mass greater than 0.4 solar masses. Based on an updated fit to the exponential formula, we now estimate the time of merger to be the year 2022.2 with a random uncertainty of 0.6 years.

These results greatly strengthen the original suggestion. The system presents an unprecedented opportunity to study the mechanism of stellar merger through targeted observations of a precursor.

Molnar, L. et al. (2015), AAS Meeting #225, id.415.05.
Tylenda, R., et al. (2011), AA, 528, A114.