TESS Full Frame Image Search for White Dwarf Exoplanets

We are leading a project to identify candidate exoplanets transiting white dwarf (WD) stars by searching TESS Full Frame Images (FFI) at locations of GAIA DR2 WD stars with magnitudes less than 18.0. This effort complements approved high cadence (2 minute or 30 second) observations of selected WD stars using TESS. Typical magnitudes for white dwarf stars with TESS candidate transits are from V 15.0 to 18.0. Typical candidate exoplanet periods may be 30 minutes to 4 days with transits lasting from 2 to 30 minutes. A Python code utilizing LightKurve and box fitting linear least square (BLS) periodograms is being developed to identify promising candidates. Ground-based follow-up with modest size (12” to 20” aperture) telescopes is possible because WD transits are relatively deep. Observations are being completed by an international collaboration. To date, we have found short period (~3 hour), short duration (~20 minutes) transits of small red dwarf stars and even shorter period (40 minutes) sinusoidal signals likely caused by star spots. Future work will include searching TESS FFI at locations of white dwarf stars identified in GAIA EDR3.