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تسجيل مستخدم جديدParameters of Chelyabinsk and Tunguska Objects and their Explosion Modes
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تأليف
Yu. I. Lobanovsky
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This paper describes briefly a mathematical model that relates the parameters of celestial bodies motion in the spheres of activity of the Sun and the Earth with mass-energy characteristics of these celestial bodies and their explosion modes during destruction in the Earth atmosphere, that in turn are linked with phenomena observed on the underlying surface. This model was used to calculate the characteristics of the objects which are causes of Chelyabinsk and Tunguska incidents. Thus, the basic data characterizing these two outstanding phenomena were obtained with using a regular physical-mathematical procedure without any speculative hypotheses and/or assumptions.
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This paper describes application of mathematical model that establishes relationship between parameters of celestial bodies motion in the spheres of activity of the Sun and the Earth with mass-energy characteristics of these objects and their explosi
on modes during destruction in the Earth atmosphere, that in turn are linked with phenomena observed on underlying surface. This model was used to calculate the characteristics of objects that caused the Chelyabinsk and Tunguska explosions with using of its trajectory parameters described in recent scientific publications (late 2013 - early 2014). It turned out that the size of Chelyabinsk meteoroid was equal to 180 - 185 meters, and its mass was close to 1.8 megatons. Energy of its explosion was equal to 57 megatons of TNT, size of Tunguska meteoroid was equal to 105 m, mass - 0.35 megatons, while energy of explosion was about of 14.5 megatons of TNT. Due to the common origin of these two celestial bodies their average density was equal - about of 570 kg/m^3.
The orbit of the Chelyabinsk object is calculated, applying the least-squares method directly to astrometric positions. The dynamical evolution of this object in the past is studied by integrating equations of motion for particles with orbits from th
e confidence region. It is found that the majority of the Chelyabinsk clones reach the near-Sun state. 67 percent of these objects have collisions with the Sun for 15 Myr in our numerical simulations. The distribution of minimum solar distances shows that the most probable time for the encounters of the Chelyabinsk object with the Sun lies in the interval from -0.8 Myr to -2 Myr. This is consistent with the estimate of a cosmic ray exposure age of 1.2 Myr (Popova et al 2013). A parent body of the Chelyabinsk object should experience strong tidal and thermal effects at this time. The possible association of the Chelyabinsk object with 86039 (1999 NC43) and 2008 DJ is discussed.
We explored the statistical and compositional link between Chelyabinsk meteoroid and potentially hazardous asteroid (86039) 1999 NC43 to investigate their proposed relation proposed by Boroviv{c}ka et al. (2013). Using detailed computation we confirm
that the orbit of the Chelyabinsk impactor is anomalously close to 1999 NC43. We find about (1-3) x 10-4 likelihood of that to happen by chance. Taking the standpoint that the Chelyabinsk impactor indeed separated from 1999 NC43 by a cratering or rotational fission event, we run a forward probability calculation, which is an independent statistical test. However, we find this scenario is unlikely at the about (10-3 -10-2) level. We also verified compositional link between Chelyabinska and 1999NC43. Mineralogical analysis of Chelyabinsk (LL chondrite) and (8) Flora (the largest member of the presumed LL chondrite parent family) shows that their olivine and pyroxene chemistries are similar to LL chondrites. Similar analysis of 1999 NC43 shows that its olivine and pyroxene chemistries are more similar to L chondrites than LL chondrites (like Chelyabinsk). We also took photometric observations of 1999 NC43 over 54 nights during two apparitions (2000, 2014). The lightcurve of 1999 NC43 resembles simulated lightcurves of tumblers in Short-Axis Mode with the mean wobbling angle 20-30 deg. While, a mechanism of the non-principal axis rotation excitation is unclear, we can rule out the formation of asteroid in disruption of its parent body as a plausible cause, as it is unlikely that the rotation of an asteroid fragment from catastrophic disruption would be nearly completely halted. Considering all these facts, we find the proposed link between the Chelyabinsk meteoroid and the asteroid 1999 NC43 to be unlikely.
About one-fourth of the universe is thought to consist of dark matter. Yet there is no clear understanding about the nature of these particles. Commonly discussed dark matter candidates includes the so called WIMPs or weakly interacting massive parti
cles with masses from about 10GeV to 1TeV. These particles can gravitate to form a new class of objects in dark matter halos or around the galactic centre. We study in some detail many properties of these objects; which are dark matter dominated and bound by their self gravity; their formation and possibilities of their detection. Implications of the presence of such objects for star formation are also discussed. These objects could provide the possibility of forming primordial black holes distinct from the usual Hawking black holes and they could also provide a scenario for short duration gamma ray bursts, avoiding the baryon load problem.
The mineralogy and physical properties of Chelyabinsk meteorites (fall, February 15, 2013) are presented. Three types of meteorite material are present, described as the light-colored, dark-colored, and impact-melt lithologies. All are of LL5 composi
tion with the impact-melt lithology being close to whole-rock melt and the dark-colored lithology being shock-darkened due to partial melting of iron metal and sulfides. This enables us to study the effect of increasing shock on material with identical composition and origin. Based on the magnetic susceptibility, the Chelyabinsk meteorites are richer in metallic iron as compared to other LL chondrites. The measured bulk and grain densities and the porosity closely resemble other LL chondrites. Shock darkening does not have a significant effect on the material physical properties, but causes a decrease of reflectance and decrease in silicate absorption bands in the reflectance spectra. This is similar to the space weathering effects observed on asteroids. However, compared to space weathered materials, there is a negligible to minor slope change observed in impact-melt and shock-darkened meteorite spectra. Thus, it is possible that some dark asteroids with invisible silicate absorption bands may be composed of relatively fresh shock-darkened chondritic material.
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