NEID Reveals The Warm Neptune GJ 3470b has a Polar Orbit

The warm Neptune GJ 3470b transits a nearby (d=29pc) bright M-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5m Telescope at Kitt Peak Observatory, we model the Rossiter-Mclaughlin effect and obtain a sky-projected obliquity of 100 degrees. Using the known rotation period, stellar radius, and the vsini estimate from our analysis, we derive a true obliquity of 96 degrees revealing that GJ 3470b is on a polar orbit. We additionally detect a candidate RV slope using out-of-transit radial velocities, and we show that if the slope is due to an outer companion, such a companion would be able to explain the polar orbit of the inner warm Neptune. GJ 3470b joins a growing sample of warm Neptunes orbiting cool stars that are observed to have polar and mildly eccentric orbits with evaporating atmospheres. This sample could be highlighting the presence of a new class of planetary systems: warm Neptunes driven to polar orbits due to interactions with outer companions.