K2 observations of the pulsating subdwarf B stars UY Sex and V1405 Ori

We processed and analyzed K2 observations of the pulsating subdwarf B (sdBV) stars UYSex and V1405Ori. We detect 97 p-mode pulsations in UYSex while we discover V1405Ori to be a rare rich hybrid pulsator with over 100 p-mode pulsations and 19 g-mode pulsations. We detect frequency multiplets, which we use to identify pulsation modes as well as determine rotation periods. For UYSex, we find a rotation period of the envelope of 24.6 ± 3.5 days and for V1405Ori, we find a rotation period of 0.555± 0.029d for the p modes and a marginal detection of 4.2± 0.4 d for the g modes. We discover that V1405Ori is unique among sdBV stars observed to date. It is a rich hybrid pulsator, allowing us to simultaneously probe the envelope and interior; its frequency multiplets indicate V1405Ori to be rotating differentially with the core rotating more slowly than the envelope; and it is also in a short-period binary (0.398days) with an envelope that is nearly, but not quite tidally locked. For both stars we have obtained spectroscopic follow-up observations and examine combining them with GAIA parallaxes and archival photometry to determine fundamental properties. Our derived masses are inconsistent with spectroscopy and previous determinations and indicate problems with the methodology.