Astronomy and Astrophysics, volume 530A, 113-113 (2011/6-1)
Bulk density of small meteoroids.
KIKWAYA J.-B., CAMPBELL-BROWN M. and BROWN P.G.
Abstract (from CDS):
Here we report on precise metric and photometric observations of 107 optical meteors, which were simultaneously recorded at multiple stations using three different intensified video camera systems. The purpose is to estimate bulk meteoroid density, link small meteoroids to their parent bodies based on dynamical and physical density values expected for different small body populations, to better understand and explain the dynamical evolution of meteoroids after release from their parent bodies. The video systems used had image sizes ranging from 640x480 to 1360x1036 pixels, with pixel scales from 0.01° per pixel to 0.05° per pixel, and limiting meteor magnitudes ranging from Mv=+2.5 to +6.0. We find that 78% of our sample show noticeable deceleration, allowing more robust constraints to be placed on density estimates. The density of each meteoroid is estimated by simultaneously fitting the observed deceleration and lightcurve using a model based on thermal fragmentation, conservation of energy and momentum. The entire phase space of the model free parameters is explored for each event to find ranges of parameters which fit the observations within the measurement uncertainty. (a) We have analysed our data by first associating each of our events with one of the five meteoroid classes. The average density of meteoroids whose orbits are asteroidal and chondritic (AC) is 4200kg/m3 suggesting an asteroidal parentage, possibly related to the high-iron content population. Meteoroids with orbits belonging to Jupiter family comets (JFCs) have an average density of 3100±300 kg/m3. This high density is found for all meteoroids with JFC-like orbits and supports the notion that the refractory material reported from the Stardust measurements of 81P/Wild 2 dust is common among the broader JFC population. This high density is also the average bulk density for the 4 meteoroids with orbits belonging to the Ecliptic shower-type class (ES) also related to JFCs. Both categories we suggest are chondritic based on their high bulk density. Meteoroids of HT (Halley type) orbits have a minimum bulk density value of 360+400–100kg/m3 and a maximum value of 1510+400–900kg/m3. This is consistent with many previous works which suggest bulk cometary meteoroid density is low. SA (Sun-approaching)-type meteoroids show a density spread from 1000kg/m3 to 4000kg/m3, reflecting multiple origins. (b) We found two different meteor showers in our sample: Perseids (10 meteoroids, ∼11% of our sample) with an average bulk density of 620kg/m3 and Northern Iota Aquariids (4 meteoroids) with an average bulk density of 3200kg/m3, consistent with the notion that the NIA derive from 2P/Encke.
meteorites, meteors, meteoroids - minor planets, asteroids: general - techniques: photometric