We confirm a 0.995 d periodic planetary transit-like signal , KOI 6705.01 , in the Kepler lightcurve of the star KIC 6423922 .
Optical and infrared spectra show that this star is a mid M-type dwarf with an effective temperature = 3327 \pm 60 K , metallicity [ Fe/H ] = -0.08 \pm 0.10 , radius = 0.31 \pm 0.03 R _ { \odot } , and mass = 0.28 \pm 0.05 M _ { \odot } .
The star is \approx 70 pc away and its space motion , rotation period , and lack of H \alpha emission indicate it is an older member of the ” thin disk ” population .
On the other hand , the star exhibits excess infrared emission suggesting a dust disk more typical of a very young star .
If the KOI 6705.01 signal is produced by a planet , the transit depth of 60 ppm means its radius is only 0.26 ^ { +0.034 } _ { -0.029 } R _ { \oplus } , or about the size of the Moon .
However , the duration ( \gtrsim 3 hr ) and time variation of KOI 6705.01 are anomalous : the signal was undetected in the first two years of the mission and increased through the latter two years .
These characteristics require implausible orbits and material properties for any planet and rule out such an explanation , although a dust cloud is possible .
We excluded several false positive scenarios including background stars , scattered light from stars that are nearby on the sky , and electronic cross-talk between detector readout channels .
We find the most likely explanation to be that KOI 6705.01 is a false positive created by charge transfer inefficiency in a detector column on which KIC 6423922 and a 1.99 d eclipsing binary both happened to fall .