Interaction of large Taurid meteoroids with the Earth's atmosphere

Abstract

Abstract.Results of the detailed analysis of the luminosity and ablation of bright Taurid, that break up into individual pieces in the Earth's atmosphere due to the aerodynamic pressure are presented. The aim of this analysis is to determine the composition and strength of Taurids on the basis of both photographic observations with small-meteor cameras and cameras with long focal length using the method of instantaneous exposure (τ exp = 5.6 × 10 −4 s). The study was carried out by constructing the theoretical meteor light curve while taking into account its fragmentation into two or more pieces and analyzing the aerodynamic pressure on the meteoroid at the point of splitting. The bulk densities of Taurids were obtained from an analysis of the observed light curves and compared with the strength categories obtained on the basis the data of the aerodynamic pressure at the point of meteoroid splitting. Comparing the resulting values with the known strength properties of various materials lets us conclude that Taurids could be considered structurally fragile bodies that fall into the a-strength category, have a density of 2.3 to 2.8 g/cm 3 , and can be characterized as carbonaceous chondrites. We discovered a connection between observed low-frequency pulsations of brightness of the splitting Taurids and the flares of individual pieces. We suggested that the observed lateral displacement velocity of the pieces could be caused by the explosive nature of the process of Taurid meteoroid fragmentation.

Spectra and physical properties of Taurid meteoroids

“…Taurid fireballs were previously observed to break-up under 0.05 -0.18 MPa (Konovalova, 2003). The inferred dynamic pressures in our sample of Taurid meteoroids ranges from 0.02 -0.10 MPa (Table 5), with the average fragmentation strength of 0.05 MPa placed on the lower limit of the results of Konovalova (2003).…”

“…The inferred dynamic pressures in our sample of Taurid meteoroids ranges from 0.02 -0.10 MPa (Table 5), with the average fragmentation strength of 0.05 MPa placed on the lower limit of the results of Konovalova (2003). Expectedly, meteoroids of higher mineralogical density fragmented under higher pressures than the low-density bodies.…”

Orbit, emission spectrum, and photometric analysis of two flickering sporadic fireballs

“…3 also shows that the flickering effect practically disappears after the main fulguration. In this case, the most likely explanation for the flickering behavior observed for the "Fuencaliente" fireball would be a mechanism of successive detachment of fragments (wreckages) (Oleak 1964;Konovalova 2003).…”

“…For a density ρ m = 3.7 g cm −3 , the calculated diameter yields 47 ± 2 cm for the "Fuencaliente" meteoroid and 12.8 ± 1.5 cm for "Sevilla". Observational data show that both, sporadic bright fireballs (Getman 1993;Brown et al 1998;Beech 2001) but also bright bolides belonging to annual meteor showers such as the Geminids (Halliday 1963;Babadzhanov & Konovalova 2004) and the Taurids (Konovalova 2003) show quasi-periodic brightness variations during the flight in the Earth's atmosphere. The flickering frequencies reported in the literature vary from a few Hz (low-frequency flickering) to about 500 Hz (high-frequency flickering).…”

Some features of Geminid meteoroid disintegration in the Earth's atmosphere

“…The pulsations of brightness were observed for 6 of 12 Geminid fireballs photographed according to the Meteoroid Observation and Recovery Program (MORP) of Canada (Halliday 1988). In scientific publications there are examples of meteors whose flickering frequency varies from several Hz up to hundreds of Hz (low-frequency pulsations) (Kramer 1966;Getman 1993;Beech & Brown 2000;Konovalova 2003), but the flickering frequency of Geminids is almost ten times as much, the flickering starts suddenly, approximately from the middle of a meteor trajectory and remain steady down to its end. Thus the frequency of flickerings increases in the process of penetration of the meteoroid into the atmosphere, and the amplitude of flickering remains practically nearly constant during the whole visible path.…”