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Communication Dans Un Congrès Année : 2022

PECULIAR COMETS EJECTED EARLY IN SOLAR SYSTEM FORMATION

Résumé

Introduction: Radio observations of the long period comet C/2016 R2 (PanSTARRS), hereafter R2, revealed that it was a CO-rich comet remarkably depleted in water [1]. Further, the spectrum was dominated by bands of CO + as well as N2 + , the latter of which never being seen in such abundance in comets before [2][3]. This CO and N2-rich and water-poor composition, along with none of the usual neutrals seen in most cometary spectra, makes R2 a unique and intriguing specimen. Understanding the dynamical history of this comet is thus of essential importance to understanding the timeline of planetesimal formation in our solar system. However, tracking such a small object backward with any degree of certainty is made impossible by the inherent chaotic nature of its motion due to frequent close encounters with the gas giants. Alternative measures must be employed in order to determine where this unique comet originated from. Two studies have independently estimated the possible origin of this comet from building blocks formed in a peculiar region in the protoplanetary disk, near the ice line of CO and N2. By evaluating the radial transport of volatiles in the Protoplanetary Disk (PPD), Mousis (2021) [4] found that R2's peculiar N2/CO ratio could be replicated by agglomeration from particles near the N2 and CO icelines, i.e. within the 10-15 au region. Meanwhile, the CO/H2O ratio would remain deeply depleted inward of the CO iceline (see Figure 1). Similarly, Price (2021) [5] model the effect of drifting solid material in the PPD and find that the ideal location for the objects to form is beyond CO iceline. However, this would indicate that more CO rich comets should exist than have previously been observed. Methods: Here we explore the potential fates of comets formed from these building blocks using a numerical simulation of early solar system formation and tracking the dynamics of these objects in the Jumping Neptune scenario Nesvorny (2015) [6]. We start with five planets: Jupiter, Saturn, and three ice giants, as described by Deienno et al (2017) [7]. The planetary evolutions are selected to meet criteria of similarity with the solar system today, among which having four planets and Jupiter and Saturn having suffered a rapid separation of their orbits due to an instability while crossing a mean motion resonance. We fill the disk between 4 au to avoid the inner solar system, and 50 au with massless comet facsimiles or 'clones'. We then use a modified SWIFT numerical
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hal-03853412 , version 1 (15-11-2022)

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  • HAL Id : hal-03853412 , version 1

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Sarah E Anderson, Jean-Marc C. Petit, B. Noyelles, Olivier Mousis, Philippe Rousselot. PECULIAR COMETS EJECTED EARLY IN SOLAR SYSTEM FORMATION. 53rd Lunar and Planetary Science Conference, Mar 2022, The Woodlands, TX, United States. ⟨hal-03853412⟩
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