  In this letter we present our first high contrast NACO/SDI observations of
the exoplanet host star Gl86 and results from NACO spectroscopy. Els et al.
(2001) found a faint co-moving companion located only ~2arcsec east of the
exoplanet host star Gl86A. Our high contrast SDI observations rule out
additional stellar companions from 1AU up to 23AU, and are sensitive for faint
T dwarf companions down to 35MJup. We present evidence for orbital motion of
Gl86B around the exoplanet host star Gl86A, which finally confirms that this is
a bound binary system. With the given photometry from Els et al. (2001) and the
obtained NACO spectroscopy we prove that the companion Gl86B is a cool white
dwarf with an effective temperature of 5000+-500K. This is the first confirmed
white dwarf companion to an exoplanet host star and the first observational
confirmation that planets survive the post main sequence evolution of a star
from which they are separated by only one to two dozen astronomical units
(giant phase and planetary nebula) as expected from theory.
