An optical survey for millimeter-sized interstellar meteoroids

Abstract

We report high-resolution multi-station observations of meteors by the Canadian Automated Meteor Observatory recorded from 2009 June to 2010 August. Our survey has a limiting detection magnitude of +5mag in R band, equivalent to a limiting meteoroid mass of ∼2 × 10-7kg. The high metric trajectory accuracy (of the order of 30m perpendicular to the solution and 200m along track) allows us to determine velocities with average uncertainty of <1.5% in speed and ∼0°.4 in the radiant direction. A total of 1739 meteors had measured orbits. The data have been searched for meteors in hyperbolic orbits, which are potentially of interstellar origin. We found 22 potential hyperbolic meteors among our sample, with only two of them having a speed at least 3σ above the hyperbolic limit. For our one-year survey we find no clear evidence of interstellar meteoroids at millimeter sizes in a weighted time-area product of ∼104km2hr. Backward integrations performed for these 22 potentially hyperbolic meteors to check for close encounters with planets show no considerable changes in their orbits. Detailed examination leads us to conclude that our few identified events are most likely the result of measurement error. We find an upper limit of f ISP < 2 × 10-4km-2hr-1 for the flux of interstellar meteoroids at Earth with a limiting mass of m > 2 × 10-7kg. © 2012. The American Astronomical Society. All rights reserved.