Tunguska : un impacteur issu des Taurides ?

[Patrice Renaut]

Une hypothèse intéressante et un rrendez vous à ne pas manquer en juin prochain ...

P53D-2998: Was Tunguska a Beta Taurid? 2019 Observational Campaigns can Test Hypothesis
Hydrocode models of the 1908 Tunguska airburst have provided reasonable explanations for most of the phenomena associated with that event, from the shape of the treefall pattern to bright nights over Europe (Boslough & Crawford, 1997; 2008). Similar models are used for the damage component of probabilistic risk assessment and cost/benefit analysis for planetary defense. Nevertheless, there is still an enormous range in model-based estimates of the size of the Tunguska impactor and explosive yield, from as low as 3 to as high as 20 megatons. This range of possible sizes, combined with the NEO population estimate, leaves us with one unsatisfying conclusion: the Tunguska event was an extreme outlier. The probability of an impact of that magnitude having happened only 110 years ago is extremely low.The frequency of the smallest and largest possible Tunguska-like events should be on the order of once every thousand and ten thousand years, respectively.
One way out of this dilemma is to question a built-in assumption in our probability estimates that small NEOs are effectively distributed randomly. Whereas the most sensational claims of “coherent catastrophism” lack merit, it is reasonable to speculate that the Taurid complex has significant concentrations of Tunguska-sized fragments that are too small to be observed unless in the vicinity of the Earth. Large fireballs--some associated with meter-class impactors--were observed during the November 2015 Taurid swarm return (Spurny et al., 2017). Several small asteroids, such as 2015 TX24, have orbits that are nearly identical to the 2015 Taurid fireballs (Olech et al., 2016; 2017). When the Earth intersects this stream, the impact probability is elevated. If the Tunguska object was a member of a Beta Taurid stream (Kresák, 1978) then the last week in June 2019 will be the next occasion with a high probability for Tunguska-like collisions or near-misses (Asher & Clube, 1993; Asher & Izumi, 1998). Because the Beta Taurids approach from the sunward side, we propose a survey designed to observe such objects after they have passed into the night sky in late June. Fortunately, the Moon will be new on July 3 and will not interfere significantly with such observations. Moreover, the possibility of enhanced daylight fireballs and significant airbursts should be anticipated during that time.

[Abderrazak Boukhris]

On en parlait il n'y a pas longtemps avec Henri, de cette possibilité d'avoir une chute massive issue d'un essaim cométaire.

viewtopic.php?f=111&t=10528

[Patrice Renaut]

Oui, je me souviens ... comme quoi il ne faut jamais dire jamais en science ! Mais ce n'est qu'une hypothèse pour l'instant et ... pas facile à vérifier.