A decadal survey of the Daytime Arietid meteor shower using the Canadian Meteor Orbit Radar

We present results from a 12 year survey of the Daytime Arietid meteor shower using the Canadian Meteor Orbit Radar, a VHF backscattering orbital meteor radar, covering the interval 2002-2013. This survey recorded more than 2 x 10(4) Daytime Arietid orbits having representative masses of 8 x 10(-8) kg and sizes of approximate to 0.4 mm. The core activity for the Arietids is found in the range 73.degrees 5 <= lambda(circle dot) <= 84.degrees 5 and shows a broad 4-d maximum centred near lambda(circle dot) = 80.degrees 5 of 0.04 meteoroids km(-2) h(-1) producing meteors of equivalent radio magnitude of +6.5 from a mean radiant at alpha(g) = 44.degrees 9 +/- 1.degrees 1, delta(g) = 25.degrees 5 +/- 1.degrees 0. During the plateau of shower peak activity, the mass index of the stream reaches a minimum with s = 1.6-1.7. Contamination from another nearby shower (likely the Daytime Zeta Perseids) and/or sub-streams showing different orbits compared to the core of the stream is evident in the interval 60.degrees 5 <= lambda(circle dot) <= 71.degrees 5. Similar contamination beyond lambda(circle dot) = 84.degrees 5 may be due to the Helion sporadic source. We also characterized the deceleration profiles for Daytime Arietid meteor echoes using several independent speed techniques including Fresnel pre-t(0), Fresnel amplitude oscillation and time-of-flight speeds which together with modelling produced a best estimate for the stream's out-of-atmosphere speed of v(infinity) = 40.5 +/- 0.7 km s(-1). The mean radar orbit from our study is noticeably smaller in semi-major axis and eccentricity than is found for larger Arietids measured with optical systems, a difference which if real indicates a particle-size sorting of the stream orbit. The broad activity maximum, long duration of activity and particle-size dependence of the orbital elements suggest the stream is too old to have been solely formed during the breakup of the parent comet of the Marsden sunskirters about a millennium ago as proposed by Sekanina & Chodas.