PB 8783: the first sdO star suitable for asteroseismic modeling?

Pulsating hot subdwarf stars are one of the showcases of asteroseismology. Thanks to the combination of rich pulsation spectra and state-of-the-art modelling tools it is possible to tightly constrain fundamental parameters such as the stellar mass. One of the remaining mysteries is the marked difference between the hot subdwarf (sdB and sdO) population observed in the Galactic field and in globular clusters (GCs). The few hot subdwarf pulsators so far discovered in GCs do not appear to have clear counterparts among the field population.

Recently, it was suggested that PB8783, one of the very first sdB pulsators discovered in 1997, may in fact be an unrecognised hot sdO star with very similar properties to the GC pulsators. We present here new, high-resolution UVES spectroscopy of PB8783 as well as an asteroseismic analysis of the pulsator and answer the question: ordinary sdB or first field counterpart to the GC pulsators?