A pulsation zoo in the hot subdwarf B star KIC 10139564 observed by Kepler

Abstract

We present our analyses of 15 months of Kepler data on KIC 10139564. We\ndetected 57 periodicities with a variety of properties not previously observed\nall together in one pulsating subdwarf B star. Ten of the periodicities were\nfound in the low-frequency region, and we associate them with nonradial\ng-modes. The other periodicities were found in the high-frequency region, which\nare likely p-modes. We discovered that most of the periodicities are components\nof multiplets with a common spacing. Assuming that multiplets are caused by\nrotation, we derive a rotation period of 25.6(1.8) days. The multiplets also\nallow us to identify the pulsations to an unprecedented extent for this class\nof pulsator. We also detect l<=2 multiplets, which are sensitive to the\npulsation inclination and can constrain limb darkening via geometric\ncancellation factors. While most periodicities are stable, we detected several\nregions that show complex patterns. Detailed analyses showed these regions are\ncomplicated by several factors. Two are combination frequencies that originate\nin the superNyquist region and were found to be reflected below the Nyquist\nfrequency. The Fourier peaks are clear in the superNyquist region, but the\norbital motion of Kepler smears the Nyquist frequency in the barycentric\nreference frame and this effect is passed on to the subNyquist reflections.\nOthers are likely multiplets but unstable in amplitudes and/or frequencies. The\ndensity of periodicities also make KIC 10139564 challenging to explain using\npublished models. This menagerie of properties should provide tight constraints\non structural models, making this subdwarf B star the most promising for\napplying asteroseismology.\n