How Meteor Showers Can Guide the Search for Long-period Comets

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With orbital periods longer than 200 yr, most long-period comets (LPCs) remain undiscovered until they are in-bound toward perihelion. The comets that pass close to Earth’s orbit are potentially hazardous objects. Those with orbital periods up to ∼4000 yr tend to have passed close to Earth’s orbit in a previous orbit and produced a meteoroid stream dense enough to be detected at Earth as a meteor shower. In anticipation of Rubin Observatory’s Legacy Survey of Space and Time (LSST), we investigate how these meteor showers can guide dedicated searches for their parent comets. Assuming search parameters informed by LSST, we calculated where the 17 known parent bodies of LPC meteor showers would have been discovered based on a cloud of synthetic comets generated from the shower properties as measured at Earth. We find that the synthetic comets predict the on-sky location of the parent comets at the time of their discovery. The parent comet’s location on average would have been 1.°51 ± 1.°19 from a line fit through the synthetic comet cloud. The difference between the heliocentric distance of the parent and mean heliocentric distance of synthetic comets on the line was 2.09 ± 1.89 au for comets with unknown absolute nuclear magnitudes and 0.96 ± 0.80 au for comets with known absolute nuclear magnitudes. We applied this method to the σ-Hydrids, the proposed meteor shower of comet Nishimura, and found that it successfully matched the pre-covery location of this comet 8 months prior to Nishimura’s discovery.