An Optical Survey for mm-Sized Interstellar Meteoroids

TL;DR

This study used high-resolution multi-station observations to search for interstellar meteoroids of millimeter size, finding no definitive evidence and setting an upper flux limit based on a year of data.

Contribution

First high-precision multi-station survey targeting mm-sized interstellar meteoroids, establishing upper flux limits and analyzing potential hyperbolic meteors.

Findings

No confirmed interstellar meteoroids detected.

Upper flux limit of < 2×10⁻⁴ per km² per hour for meteoroids > 2×10⁻⁷ kg.

Measurement errors likely explain the few hyperbolic candidates.

Abstract

We report high resolution multi-station observations of meteors by the Canadian Automated Meteor Observatory (CAMO) recorded from June 2009 to August 2010. Our survey has a limiting detection magnitude of +5 mag in R-band, equivalent to a limiting meteoroid mass of ~2*E-7 kg. The high metric trajectory accuracy (of the order of 30 m perpendicular to the solution and 200 m along-track) allows us to determine velocities with average uncertainty of < 1.5% in speed and ~0.4 degr in radiant direction. A total of 1739 meteors had measured orbits. The data has 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 three sigma above the hyperbolic limit. For our one year survey we find no clear evidence of interstellar meteoroids at mm-sizes in a weighted time-area product of ~1*E4 km^2*h. 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*E-4/(km^2*h) for the flux of interstellar meteoroids at Earth with a limiting mass of m > 2*E-7 kg.