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SUMMARY:The cometary delivery of prebiotic feedstock molecules to the earl
 y-Earth and rocky exoplanets - Richard Anslow (University of Cambridge)
DTSTART:20240508T121500Z
DTEND:20240508T124000Z
UID:TALK216676@talks.cam.ac.uk
CONTACT:Hannah Uebler
DESCRIPTION:The delivery of prebiotic feedstocks molecules\, such as hydro
 gen cyanide (HCN)\, during cometary impacts may have significantly influen
 ced prebiotic chemistry on the early Earth\, motivated by the discovery of
  a rich diversity of CHN- and CHS-bearing molecules on solar system comets
 . Numerical experiments have demonstrated that HCN survival during cometar
 y impacts is however only possible in oblique impacts at very low velociti
 es. In this talk I will discuss the effects of stellar mass\, and planetar
 y architecture on minimum cometary impact velocities onto rocky exoplanets
 . Using both an analytical model and numerical N-body simulations\, we sho
 w the lowest impact velocities occur for low-mass planets in tightly-packe
 d planetary systems around high-mass (i.e.\, Solar-mass) stars\, enabling 
 the intact delivery of prebiotic feedstock molecules. I will finish by dis
 cussing a specific origins scenario\, proposed to achieve favourable condi
 tions for subsequent prebiotic chemistry\, which invokes the arrival of a 
 secondary impactor in the same location. We consider the atmospheric fragm
 entation of cometary impactors\, and use the lunar crater record to quanti
 tatively evaluate the likelihood of these `double impact' scenarios on the
  early-Earth. These scenarios are found to be extremely unlikely settings 
 for the initial stages of prebiotic chemistry\, unless there was a particu
 larly high impact rate on the early-Earth\, and global environmental condi
 tions conducive to successful cometary delivery.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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