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On the Transfer of Meteorites (and Life?) from Earth to the Gl 581 System Tetsuya Hara, Masanobu Shigeyasu, Kazuma Takagi, Daigo Kajiura Deptment of Physics, Kyoto Sangyo University, Kyoto 603–8555, AP26113 Japan It is investigated the probability that the meteorites of Earth origin are transferred to the super-Earth planets in the Gl 581 system. We take the collisional ejection process of the Chicxulub crater event (Hildebrand et al. 1991) as Earth origin. If we assume the appropriate size of the meteorites (<1 cm in diameter), the number of meteorites to reach the Gl 581 system could be much greater than one. We have followed the ejection and capture rates estimated by Melosh (2003) and the discussion by Wallis and Wickramasinghe (2004). We believe that the ejection rate estimated by Melosh as 15 rocks (>10 cm diameter) each year from solar system seems to be too small. Although it is not certain that the micro-organisms within the size (<1 cm) of meteorites are still viable for several Myr, Earth origin meteorites could be transferred to the Gl 581 system. If it is viable, we should consider the possibility of meteorites exchange between stellar systems more seriously. Recently it has been reported that the detection
of the super-Earth planet in the Gl 581 system which resides at the warming edge of the habitable zone of the star (Udry et al. 2007). There has been established that CH5424802 rocks can be ejected from planetary surface by colliding asteroids and comets. The Chicxulub crater event 65 Myr ago provides evidence of the collisional ejection process. The meteorites size is estimated about 10 km in diameter. The concept that micro-organisms could be transported has begun to attract scientific LY3039478 attention. To estimate the transfer probability, we put parameters as following
that N 0 rocks are ejected from the solar system, the distance to the nearby star is denoted by ‘s’, and the cross section of the rock capture by the star system is σ. Then the number of captured rocks is N impact Immune system = N 0 σ/(4πs 2). When the Chicxulub meteorite collided to Earth, it could be estimated that almost the same amount mass could be ejected from Earth. Then it is assumed that the ejected mass from the solar system is f 1 × f 2 × M, where M is the mass of the Chicxulub meteorite. The factor f 1 (0.3) denotes the fraction of the mass ejected from Earth and f 2 (0.3) denotes the fraction of the mass ejected from the solar system. Taking that the mean diameter of rocks is r (1 cm) and the estimated diameter of the Chicxulub meteorite is R (10 km), the number of ejected rocks from solar system is N 0 f 1 f 2 (R/r) 3 1017. The distance to the Gl 581 is 20 light years so we take the representative value for s (1020 cm). The problem is the cross section σ.