Asteroseismic analysis of the pulsating subdwarf B star KIC 11558725: an sdB+WD system with divergent frequency multiplets and mode trapping observed by Kepler

We analyse the full Kepler short cadence data set of the pulsating subdwarf B star KIC 11558725. KIC 11558725 is in an sdB+WD binary system with a period of 10.05 d and is known to be subsynchronously rotating. From the full data set, we detected 245 pulsation frequencies, mostly in the gravity (g-) mode region, but some in the pressure (p-) mode region as well. We are able to identify 142 of these pulsations as l <= 2 modes and 27 as l = 6 modes. Frequency splittings in the g- and p-mode regions indicate that KIC 11558725 is a solid-body rotator with a rotation period of similar to 44 d. The l = 6 multiplets do not show a constant splitting, with the splitting increasing over the course of the observations. Multiplet structure constrains the inclination of the pulsation axis to be greater than similar to 80 degrees. KIC 11558725 also displays mode trapping in two regions of its asymptotic sequence.