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Optical spectroscopy of the blue star KIC 10449976 shows that it is anextremely helium-rich subdwarf with effective temperature T=40000+/-300 K andsurface gravity log g=5.3+/-0.1. Radial-velocity measurements over a five-daytimescale show an upper variability limit of ~50+/-20 km/s. Kepler photometryof KIC 10449976 in both long and short cadence modes shows evidence for aperiodic modulation on a timescale of ~3.9 days. We have examined thepossibility that this modulation is not astrophysical but conclude it is mostlikely real. We discuss whether the modulation could be caused by a low-masscompanion, by stellar pulsations, or by spots. The identification of any one ofthese as cause has important consequences for understanding the origin ofhelium-rich subdwarfs.

KIC 10449976: discovery of an extreme-helium subdwarf in the Kepler field