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A search for interstellar meteoroids using the Canadian Meteor Orbit Radar (CMOR)


Using the CMOR system, a search was conducted through 2.5 years (more than 1.5 million orbits) of archived data for meteoroids having unbound hyperbolic orbits around the Sun. Making use of the fact that each echo has an individually measured error, we were able to apply a cut-off for heliocentric speeds both more than two, and three standard deviations above the parabolic limit as our main selection criterion. CMOR has a minimum detectable particle radius near 100 μm for interstellar meteoroids. While these sizes are much larger than reported by the radar detections of extrasolar meteoroids by AMOR or Arecibo, the interstellar meteoroid population at these sizes would be of great astrophysical interest as such particles are more likely to remain unperturbed by external forces found in the interstellar medium, and thus, more likely to be traceable to their original source regions. It was found that a lower limit of approximately 0.0008% of the echoes (for the 3σ case) were of possible interstellar origin. For our effective limiting mass of 1×10−8 kg, this represents a flux of meteoroids arriving at the Earth of 6×10−6 meteoroids/km2/h. For our 2σ results, the lower limit was 0.003%, with a flux of 2×10−5 meteoroids/km2/h. The total number of events was too low to be statistically meaningful in determining any temporal or directional variations.

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The authors wish to thank the NASA Space Environment and Effects program for substantial funding support to operate and maintain the CMOR facility. RJW thanks the Natural Sciences and Engineering Research Council of Canada for providing an undergraduate student research award. PGB thanks the Canada Research Chair program and the Natural Sciences and Engineering Research Council for additional funding support.

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Weryk, R., Brown, P. A search for interstellar meteoroids using the Canadian Meteor Orbit Radar (CMOR). Earth Moon Planet 95, 221–227 (2004).

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  • Interstellar
  • meteoroids
  • meteors
  • radar