KIC 8462852's Strange Light Curve is due to the Start of a Late Heavy Bombardment

IRTF/SPEX Observations of the Unusual Kepler Lightcurve System KIC8462852

Authors:

Lisse et al

Abstract:

We have utilized the NASA IRTF 3m SpeX instrument's high resolution spectral mode (Rayner et al. 2003) to observe and characterize the near-infrared flux emanating from the unusual Kepler lightcurve system KIC8462852. By comparing the resulting 0.8 to 4.2 um spectrum to a mesh of model photospheric spectra, the 6 emission line analysis of the Rayner et al. 2009 catalogue, and the 25 system collection of debris disks we have observed to date using SpeX under the Near InfraRed Debris disk Survey (NIRDS; Lisse et al. 2016), we have been able to additionally characterize the system. Within the errors of our measurements, this star looks like a normal solar abundance main sequence F1V to F3V dwarf star without any obvious traces of significant circumstellar dust or gas. Using Connelley & Greene's (2014) emission measures, we also see no evidence of significant ongoing accretion onto the star nor any stellar outflow away from it. Our results are inconsistent with large amounts of static close-in obscuring material or the unusual behavior of a YSO system, but are consistent with the favored episodic models of a Gyr old stellar system favored by Boyajian et al. (2015). We speculate that KIC8462852, like the approximately 1.4 Gyr old F2V system {\eta} Corvi (Wyatt et al. 2005, Chen et al. 2006, Lisse et al. 2012), is undergoing a Late Heavy Bombardment, but is only in its very early stages.