NASA Astrobiology; 2nd Session of the CLEVER Planets Seminar Series

Status Report From: NASA Biological & Physical Science
Posted: Friday, September 17, 2021
NExSS CLEVER Planets Seminar Series
Episode 2: Tuesday, September 21, 2021
Prof. Anders Johansen
University of Copenhagen
Title: Formation of Terrestrial Planets by Pebble Accretion

Date: September 21st, 2021

Time: 1PM Eastern time

Abstract: The formation of the terrestrial planets in the Solar System is normally considered to last several 10s of million years and to have proceeded by giant impacts within a population of Mars-sized protoplanets. Observations of protoplanetary discs around young stars reveal that such discs host several hundred Earth masses of mm-cm sized pebbles. This inspired the pebble accretion theory for planet formation where the cores of giant planets grow by rapid accretion of these pebbles. By extension, pebble accretion should be an important process in terrestrial planet formation as well. I present a series of new papers where we show that Venus, Earth and Mars likely formed within 3-5 Myr by rapid pebble accretion. Volatiles such as water, nitrogen and carbon are delivered by small pebbles that are accreted at the earliest stages of planetary growth. Partition of these volatiles between core, mantle and atmosphere combined with early atmospheric loss gives good matches to the modern atmospheres and water reservoirs of Venus, Earth and Mars. Pebble accretion thus gives a quantitative prediction of volatile budgets and atmospheric compositions of terrestrial planets without invoking stochastic giant impacts as the delivery source.
Register in advance for this webinar (registration is required for the first attendance only, you will then be automatically registered for all the following seminars).

Past talks of the CLEVER Planets Seminar Series can be found on YouTube.
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