Binary Host Star Imaging
Complementary to my spectroscopic study of binary host stars is my interest in using high spatial resolution imaging to detect planets in multiple stellar systems and determine the influence of multiplicity on planet formation, migration, and evolution. I published a comparison of high resolution optical spectroscopic versus high contrast imaging techniques for detecting close companions to Kepler objects of interest (Teske et al. 2015b), finding that the two techniques often do not overlap in the properties of companions they detect, suggesting that many KOIs may have more than one companion. This work was done as part of the Differential Speckle Survey Instrument (DSSI) team, the only group conducting high resolution, high contrast speckle "snapshot" observations (60 millisec) at large telescopes for Kepler-related follow-up (Horch et al. 2012, 2014; Everett et al. 2015; Howell et al. 2011).
Above: Plots from Teske et al. (2015), created by UC Berkeley graduate student Lea Hirsch, showing the results of the imaging data analysis for KOI 5 in section 3.1 of our paper. Left: Primary KOI absolute photometry contours, and companion photometry contours, calculated from observed F692 magnitude and assuming it lies at the same distance and has the same age and metallicity as the KOI, mapped on the same (primary KOI) isochrone. The red point represents the absolute magnitude and "true" color for the companion (assuming it is bound), calculated from relative color information. The spread in color of the contours represents the spread in the normalized probability distribution, ranging from 1 (red) to 0 (dark blue). Middle: Same as left, but with companion photometry contours calculated from K magnitude. Right: A comparison of the overlap between the relative photometry contours of the companion. The red point here is the same as in the left and middle panels.
Above: Plots from Teske et al. (2015), showing parameter comparisons for companions found through Kobl et al. (2015)'s analysis, and derived from our analysis of imaging data. THE TAKE AWAY IS there is not good agreement! The labels refer to the companion's primary KOI. Blue circles indicate KOIs with imaging data in multiple bands, and red symbols indicate the imaging-detected companion is >0.8" away from the primary KOI. The values plotted here for the companion to KOI 3471 assume a subigant primary star. Note that the "imaging" values are those derived from our analysis, and thus may be incorrect if the companion is unbound. Top left: Teff values of the companions. Top right: Flux ratios (companion/primary) of the companions. The flux ratios measured from imaging data are in the Kepler bandpass. Bottom left: Difference in derived Teff values, versus the separation as measured from imaging data (averaged over all detections). Dashed horizontal lines designate the separation limits reported in K15. Bottom right: Difference in derived flux ratios of companions, versus the separation as measured from imaging data (averaged over all detections). Dashed horizontal lines designate the separation limits reported in Kobl et al. (2015).