Many hot subdwarf B stars (sdBs) are in close binaries, and the favoredformation channels for subdwarfs rely on mass transfer in a binary system tostrip a core He burning star of its envelope. However, these channels cannotaccount for sdBs that have been observed in long period binaries nor the narrowmass distribution of isolated (or "singleton") sdBs. We propose a new formationchannel involving the merger of a helium white dwarf and a low mass, hydrogenburning star, which addresses these issues. Hierarchical triples whose innerbinaries merge and form sdBs by this process could explain the observed longperiod subdwarf+main sequence binaries. This process would also naturallyexplain the observed slow rotational speeds of singleton sdBs. We also brieflydiscuss the implications of this formation channel for extreme horizontalbranch morphology in globular clusters and the UV upturn in ellipticalgalaxies.
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