科研之友
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摘要
We measure the activity and orbital characteristics of the eta-Aquariid meteor shower appropriate to meteoroids of 200 mu m size (mass approximate to 5-10 mu g) based on similar to 4 x 10(4) stream orbits measured by the Canadian Meteor Orbit Radar during the years 2002-2014. Significant activity from the stream is found to last from April 25-May 21 (lambda(circle dot) = 35 degrees-60 degrees) with the shower detectable approximately one week on either side of these dates just above the median background. The radiant at peak activity (lambda(circle dot) = 45.degrees 5) is located at alpha(g) = 337.. 8, delta(g) = -0.degrees 6 and shows a consistent drift of Delta alpha(g) = +0.degrees 69, Delta delta(g) = +0.degrees 60. The velocity of the stream throughout its active period remains within approximate to 1 kms(-1) of V-g = 64.3 kms(-1) found at the peak; however, there are indications this is an underestimate due to undercorrection for stream meteoroids having larger than average deceleration. The activity profile shows no mass dependence between mu g to mg sizes, but a clear asymmetry with the slope of the ascending branch having B+ = 0.135 +/- 0.003 and the descending branch B- = 0.078 +/- 0.003. The average yearly equivalent radar-measured peak Zenithal Hourly Rate (ZHR) is 50-80 from 2002-2014, with outbursts in 2004 and 2013 exceeding ZHRs of 100. The mass index shows a minimum at the time of the flux maximum with 1.8 <= s <= 1.9.
- 出版日期2015-2
