The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4) Vesta

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.Comment: 31 pages, 11 figures, and 3 tables. Published in the special issue "Planet Formation and the Rise of Life" on the journal Life. arXiv admin note: text overlap with arXiv:1309.139

Anti-correlation between multiplicity and orbital properties in exoplanetary systems as a possible record of their dynamical histories

Previous works focused on exoplanets discovered with the radial velocity (RV) method reported an anti-correlation between the orbital eccentricities of the exoplanets and the multiplicity M (i.e., number of planets) of their system. We further investigate this reported anti-correlation here using a dataset comprising exoplanets discovered with both the RV and transit methods, searching for hints of its causes by exploring the connection between the number of planets and the dynamical state of the exosystems. To examine the correlation between multiplicity and orbital eccentricity, for every multiplicity case considered (1<M<7), we computed the weighted average eccentricities instead of the median eccentricities used previously. The average eccentricities were calculated using the inverse of the uncertainty on the eccentricity values as weights. The analysis of the dynamic state of the exosystems was performed by computing their angular momentum deficit (AMD), a diagnostic parameter used in the study of solar system and recently applied to exosystems. Our results confirm the reported multiplicity-eccentricity anti-correlation and show that the use of the uncertainties on the orbital eccentricities in the analysis allows for a better agreement between data and fits. Our best fit reproduces well the behaviour of average eccentricities for all systems with M>1, including the additional cases of TRAPPIST-1 (M=7) and solar system (M=8). The AMD analysis, while not conclusive due to the limited number of exosystems that could be analysed, also suggests the existence of an anti-correlation between the multiplicity and the AMD of exosystems. This second anticorrelation, if confirmed by future studies, raises the possibility that the population of low-multiplicity exosystems is contaminated by former high-multiplicity systems that became dynamically unstable and lost some of their planets

The Compositional Dimension of Planet Formation

The great diversity of the thousands of planets known to date is proof of the multitude of ways in which formation and evolution processes can shape the life of planetary systems. Multiple formation and evolution paths, however, can result in the same planetary architecture. Because of this, unveiling the individual histories of planetary systems and their planets can prove a challenging task. The chemical composition of planets provides us with a guiding light for navigate this challenge, but to understand the information it carries we need to properly link it to the chemical composition and characteristics of the environments in which the planets formed. To achieve this goal it is necessary to combine the information and perspectives provided by a growing number of different fields of study, spanning the whole lifecycle of stars and their planetary systems. The aim of this chapter is to provide the unifying perspective needed to understand and connect such diverse information, and illustrate the process through which we can decode the message contained into the composition of planetary bodies.Comment: 45 pages, 7 figures, 4 tables; accepted as a chapter in the book "Planetary systems now", eds. Luisa M. Lara and David Jewitt, World Scientific Publishing Co Pte Lt

Planetary Formation: Lessons Learned from the Solar System and the Extrasolar Planets

Our understanding of planetary formation as derived from the Solar System, for decades the only example of a planetary system we knew, has been challenged over the last twenty years by the rich diversity of discovered extrasolar planets. The Solar System, however, still represent a unique source of detailed information on the processes shaping the formation and subsequent evolution of planets, both individually and as a whole. Over the last ten years, in particular, the study of the geochronology of meteorites supplied new and highly detailed data on the relative timescales of formation and geophysical evolution of the different classes of planetary bodies. At the same time, new theoretical works on the formation and early dynamical evolution of the giant planets helped bridging the gap between the story told by the Solar System and that coming from the extrasolar planets. This talk will provide a review of these recent advancements and discuss how they affected our understanding of the earliest and more mysterious phases of the life of planetary systems

DPI: Symplectic mapping for binary star systems for the Mercury software package

DPI is a FORTRAN77 library that supplies the symplectic mapping method for binary star systems for the Mercury N-Body software package (ascl:1201.008). The binary symplectic mapping is implemented as a hybrid symplectic method that allows close encounters and collisions between massive bodies and is therefore suitable for planetary accretion simulations. [Source code is in Astrophysics Source Code Library

Exploring the link between star and planet formation with Ariel

The goal of the Ariel space mission is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. The planetary bulk and atmospheric compositions bear the marks of the way the planets formed: Ariel’s observations will therefore provide an unprecedented wealth of data to advance our understanding of planet formation in our Galaxy. A number of environmental and evolutionary factors, however, can affect the final atmospheric composition. Here we provide a concise overview of which factors and effects of the star and planet formation processes can shape the atmospheric compositions that will be observed by Ariel, and highlight how Ariel’s characteristics make this mission optimally suited to address this very complex problem

Constraining the atmospheric elements in hot Jupiters with Ariel

One of the main objectives of the European Space Agency’s Ariel telescope (launch 2029) is to understand the formation and evolution processes of a large sample of planets in our Galaxy. Important indicators of such processes in giant planets are the elemental compositions of their atmospheres. Here we investigate the capability of Ariel to constrain four key atmospheric markers: metallicity, C/O, S/O, and N/O, for three well-known, representative hot-Jupiter atmospheres observed with transit spectroscopy, i.e. HD 209458b, HD 189733b, and WASP-121b. We have performed retrieval simulations for these targets to verify how the planetary formation markers listed above would be recovered by Ariel when observed as part of the Ariel Tier 3 survey. We have considered eight simplified different atmospheric scenarios with a cloud-free isothermal atmosphere. Additionally, extra cases were tested to illustrate the effect of C/O and metallicity in recovering the N/O. From our retrieval results, we conclude that Ariel is able to recover the majority of planetary formation markers. The contributions from CO and CO2 are dominant for the C/O in the solar scenario. In a C-rich case, C2H2, HCN, and CH4 may provide additional spectral signatures that can be captured by Ariel. In our simulations, H2S is the main tracer for the S/O in hot-Jupiter atmospheres. In the super-solar metallicity cases and the cases with C/O > 1, the increased abundance of HCN is easily detectable and the main contributor to N/O, while other N-bearing species contribute little to the N/O in the investigated atmospheres