Astronomy and Astrophysics – Astronomy
Scientific paper
Oct 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007dps....39.5401k&link_type=abstract
American Astronomical Society, DPS meeting #39, #54.01; Bulletin of the American Astronomical Society, Vol. 39, p.523
Astronomy and Astrophysics
Astronomy
Scientific paper
Using an LLLTV (low light level television) system based on second generation image intensifiers (GEN II) (Hawkes, R.L., 2001); several images of meteors have been gathered during a May 2004 campaign in London Ontario (Canada). The field of view of 6 degrees on 720x480 pixel images provides a scale of 13 m/pixel at 60 fields per second. This resolution has given more precise measurements of deceleration for very faint meteors than previously attainable. The magnitude limit for meteors is near V=+8, with stars visible to V=+11 in the instruments. The population of meteors we detected has peak brightness between magnitude +6.2 and +7.4 magnitude. Their masses computed from photometry range from 4.2 mg to 0.35 mg. Based on precise metric data, including deceleration, begin and end height and complete lightcurves, an ablation model was fit to each event (Campbell-Brown and Koschny, 2002) in an attempt to compute bulk meteoroid density. Interestingly, a large proportion of our faint meteor events were found to ablate at lower altitudes, similar to the finding of Kaiser et al (2005). The orbit of these events is consistent with an asteroidal origin and their physical properties determined through model fits suggest high densities. Although we have not performed a detailed de-biasing of our observing geometry, the high percentage of apparently asteroidal objects at these small sizes is inconsistent with earlier findings by Ceplecha (1988) who suggests 10% of meteoroids at these masses should be asteroidal in origin. We find that many of these apparently asteroidal objects also undergo extensive fragmentation, much as would be expected of cometary meteoroids. Some individual cases in our small dataset will be highlighted where high bulk densities (approaching iron) are required to adequately match the end height, brightness and observed deceleration.
Brown Peter G.
Campbell-Brown Margaret
Hawkes R.
Kikwaya Eluo Jean-Baptiste
Weryk Robert J.
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