  Many hot subdwarf B stars (sdBs) are in close binaries, and the favored
formation channels for subdwarfs rely on mass transfer in a binary system to
strip a core He burning star of its envelope. However, these channels cannot
account for sdBs that have been observed in long period binaries nor the narrow
mass distribution of isolated (or "singleton") sdBs. We propose a new formation
channel involving the merger of a helium white dwarf and a low mass, hydrogen
burning star, which addresses these issues. Hierarchical triples whose inner
binaries merge and form sdBs by this process could explain the observed long
period subdwarf+main sequence binaries. This process would also naturally
explain the observed slow rotational speeds of singleton sdBs. We also briefly
discuss the implications of this formation channel for extreme horizontal
branch morphology in globular clusters and the UV upturn in elliptical
galaxies.
