The cometary delivery of prebiotic feedstock molecules to the early-Earth and rocky exoplanets

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• Richard Anslow (University of Cambridge)
• Wednesday 08 May 2024, 13:15-13:40
• The Hoyle Lecture Theatre + Zoom .

If you have a question about this talk, please contact Hannah Uebler.

The delivery of prebiotic feedstocks molecules, such as hydrogen cyanide (HCN), during cometary impacts may have significantly influenced 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 cometary impacts is however only possible in oblique impacts at very low velocities. In this talk I will discuss the effects of stellar mass, and planetary architecture on minimum cometary impact velocities onto rocky exoplanets. Using both an analytical model and numerical N-body simulations, we show the lowest impact velocities occur for low-mass planets in tightly-packed planetary systems around high-mass (i.e., Solar-mass) stars, enabling the intact delivery of prebiotic feedstock molecules. I will finish by discussing a specific origins scenario, proposed to achieve favourable conditions for subsequent prebiotic chemistry, which invokes the arrival of a secondary impactor in the same location. We consider the atmospheric fragmentation of cometary impactors, and use the lunar crater record to quantitatively 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 particularly high impact rate on the early-Earth, and global environmental conditions conducive to successful cometary delivery.

This talk is part of the Institute of Astronomy Seminars series.

This talk is included in these lists:

• Combined External Astrophysics Talks DAMTP
• Cosmology lists
• Cosmology, Astrophysics and General Relativity
• Institute of Astronomy Seminars
• Institute of Astronomy Talk Lists
• Kavli Institute for Cosmology Talk Lists
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• The Hoyle Lecture Theatre + Zoom

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