We present 16 new , and confirm 7 previously identified , DA white dwarfs in the Kepler field through ground-based spectroscopy with the Hale 200 ^ { \prime \prime } , Kitt Peak 4-meter , and Bok 2.3-meter telescopes .
Using atmospheric models we determine their effective temperatures and surface gravities to constrain their position with respect to the ZZ Ceti ( DA pulsator ) instability strip , and look for the presence or absence of pulsation with Kepler ’ s unprecedented photometry .
Our results are as follows : i ) From our measurements of temperature and surface gravity , 12 of the 23 DA white dwarfs from this work fall well outside of the instability strip .
The Kepler photometry available for 11 of these WDs allows us to confirm that none are pulsating .
One of these eleven happens to be a presumed binary , KIC 11604781 , with a period of \sim 5 days . ii ) The remaining 11 DA white dwarfs are instability strip candidates , potentially falling within the current , empirical instability strip , after accounting for uncertainties .
These WDs will help constrain the strip ’ s location further , as eight are near the blue edge and three are near the red edge of the instability strip .
Four of these WDs do not have Kepler photometry , so ground-based photometry is needed to determine the pulsation nature of these white dwarfs .
The remaining seven have Kepler photometry available , but do not show any periodicity on typical WD pulsation timescales .