Ultra Short Period Planets in K2 III: Neighbors are Common with 12 New Multi-Planet Systems and 26 Newly Validated Planets in Campaigns 0-8, 10

Using the EVEREST photometry pipeline, we have identified 74 candidate ultra-short-period planets (orbital period P 10) and (b) short-period desert (3<=Rp<=10) planets suggests that both populations are rare. These results also provide strong evidence that we have not reached a lower planetary radius limit for planets at close proximity to a star, and suggest that additional improvements in photometry techniques would yield yet more ultra-short-period planets. The large fraction of USPs in known multi-planet systems supports origins models that involve dynamical interactions with exterior planets coupled to tidal decay of the USP orbits.