Discovery and seismological interpretation of low-amplitude modes in the pulsating DO white dwarf PG 1707+427 (V817 herculis)

We report the discovery of low-amplitude pulsation modes in the faint variable DO white dwarf PG 1707+427 (V817 Her). With the large aperture of the CFHT, enough modes were uncovered to allow us to derive a preliminary asteroseismological estimate of the mass of the star of approximately 0.7 M ⊙ . This assumes that the modes observed have a spherical harmonic index l=1