Near-Earth object velocity distributions and consequences for the Chicxulub impactor |
| |
| Authors: | SV Jeffers SP Manley ME Bailey DJ Asher |
| |
| Institution: | 1Armagh Observatory, College Hill, Armagh BT61 9DG;2School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS |
| |
| Abstract: | An Öpik-based geometric algorithm is used to compute impact probabilities and velocity distributions for various near-Earth object (NEO) populations. The resulting crater size distributions for the Earth and Moon are calculated by combining these distributions with assumed NEO size distributions and a selection of crater scaling laws. This crater probability distribution indicates that the largest craters on both the Earth and the Moon are dominated by comets. However, from a calculation of the fractional probabilities of iridium deposition, and the velocity distributions at impact of each NEO population, the only realistic possibilities for the Chicxulub impactor are a short-period comet (possibly inactive) or a near-Earth asteroid. For these classes of object, sufficiently large impacts have mean intervals of 100 and 300 Myr respectively, slightly favouring the cometary hypothesis. |
| |
| Keywords: | comets: general Earth minor planets asteroids Moon |
|
|
