scholarly journals Losing oceans: The effects of composition on the thermal component of impact-driven atmospheric loss

2020 ◽  
Vol 501 (1) ◽  
pp. 587-595
Author(s):  
John B Biersteker ◽  
Hilke E Schlichting
Keyword(s):  
Noble Gas ◽  
Terrestrial Planet ◽  
Terrestrial Planets ◽  
Thermal Heating ◽  
Atmospheric Escape ◽  
Giant Impacts ◽  
Volatile Loss ◽  
Atmospheric Loss ◽  
The Impact ◽  
Mean Molecular Weight

ABSTRACT The formation of the Solar system’s terrestrial planets concluded with a period of giant impacts. Previous works examining the volatile loss caused by the impact shock in the moon-forming impact find atmospheric losses of at most 20–30 per cent and essentially no loss of oceans. However, giant impacts also result in thermal heating, which can lead to significant atmospheric escape via a Parker-type wind. Here we show that H2O and other high-mean molecular weight outgassed species can be efficiently lost through this thermal wind if present in a hydrogen-dominated atmosphere, substantially altering the final volatile inventory of terrestrial planets. We demonstrate that a giant impact during terrestrial planet formation can remove several Earth oceans’ worth of H2O, and other heavier volatile species, together with a primordial hydrogen-dominated atmosphere. These results may offer an explanation for the observed depletion in Earth’s light noble gas budget and for its depleted xenon inventory, which suggest that Earth underwent significant atmospheric loss by the end of its accretion. Because planetary embryos are massive enough to accrete primordial hydrogen envelopes and because giant impacts are stochastic and occur concurrently with other early atmospheric evolutionary processes, our results suggest a wide diversity in terrestrial planet volatile budgets.

scholarly journals Tracing the ingredients for a habitable earth from interstellar space through planet formation

2015 ◽  
Vol 112 (29) ◽  
pp. 8965-8970 ◽  
Author(s):  
Edwin A. Bergin ◽  
Geoffrey A. Blake ◽  
Fred Ciesla ◽  
Marc M. Hirschmann ◽  
Jie Li
Keyword(s):  
Large Scale ◽  
Terrestrial Planets ◽  
Interstellar Space ◽  
Atmospheric Escape ◽  
The Core ◽  
Bulk Silicate Earth ◽  
Thermally Processed ◽  
C And N ◽  
Volatile Loss ◽  
Atmospheric Loss

We use the C/N ratio as a monitor of the delivery of key ingredients of life to nascent terrestrial worlds. Total elemental C and N contents, and their ratio, are examined for the interstellar medium, comets, chondritic meteorites, and terrestrial planets; we include an updated estimate for the bulk silicate Earth (C/N = 49.0 ± 9.3). Using a kinetic model of disk chemistry, and the sublimation/condensation temperatures of primitive molecules, we suggest that organic ices and macromolecular (refractory or carbonaceous dust) organic material are the likely initial C and N carriers. Chemical reactions in the disk can produce nebular C/N ratios of ∼1–12, comparable to those of comets and the low end estimated for planetesimals. An increase of the C/N ratio is traced between volatile-rich pristine bodies and larger volatile-depleted objects subjected to thermal/accretional metamorphism. The C/N ratios of the dominant materials accreted to terrestrial planets should therefore be higher than those seen in carbonaceous chondrites or comets. During planetary formation, we explore scenarios leading to further volatile loss and associated C/N variations owing to core formation and atmospheric escape. Key processes include relative enrichment of nitrogen in the atmosphere and preferential sequestration of carbon by the core. The high C/N bulk silicate Earth ratio therefore is best satisfied by accretion of thermally processed objects followed by large-scale atmospheric loss. These two effects must be more profound if volatile sequestration in the core is effective. The stochastic nature of these processes hints that the surface/atmospheric abundances of biosphere-essential materials will likely be variable.

scholarly journals Noble Gases in Terrestrial Planets: Evidence for Cometary Impacts?

1989 ◽  
Vol 116 (1) ◽  
pp. 429-437
Author(s):  
Tobias Owen ◽  
Akiva Bar-Nun ◽  
Idit Kleinfeld
Keyword(s):  
Low Temperatures ◽  
Noble Gases ◽  
Noble Gas ◽  
Terrestrial Planets ◽  
Laboratory Studies ◽  
The Impact ◽  
Gas Patterns ◽  
Atmosphere Of Venus

AbstractThe possible role of comets in bringing volatiles to the inner planets is investigated by means of laboratory studies of the ability of ice to trap gases at low temperatures. The pattern of the heavy noble gases formed in the atmosphere of Venus can be explained by the impact of a planetesimal composed of ices formed in the range of 20 to 30 K. The noble gas patterns on Mars and Earth are less explicable by cometary bombardment alone.

Neutral atmospheric escape in the Solar and extrasolar planetary systems

2018 ◽  
Vol 14 (S345) ◽  
pp. 168-171
Author(s):  
Dmitry V. Bisikalo ◽  
Valery I. Shematovich
Keyword(s):  
Solar System ◽  
Mass Loss ◽  
Planetary Atmospheres ◽  
Space Missions ◽  
Kinetic Approach ◽  
Terrestrial Planets ◽  
Outer Solar System ◽  
Mars Express ◽  
Atmospheric Escape ◽  
Atmospheric Loss

AbstractNew data obtained by space missions to various objects in the Solar system and observations of the outer Solar system and exoplanets by space and ground-based telescopes allowed us to conclude that the atmospheric escape plays an important role in the evolution of the terrestrial planets in the Solar system. We present the recent results of application of the kinetic approach to the problem of neutral escape from planetary atmospheres. As an example, the recent measurements by Mars Express and MAVEN spacecraft are compared with the calculations of neutral escape with the aim to understand the atmospheric loss at Mars. Also the recent calculations of the mass-loss rates of the hot Neptune and Jupiter atmospheres are presented.

scholarly journals Terrestrial Planet Formation: The Solar System and Other Systems

2004 ◽  
Vol 202 ◽  
pp. 159-166
Author(s):  
Shigeru Ida ◽  
Eiichiro Kokubo
Keyword(s):  
Solar System ◽  
Final Stage ◽  
Extrasolar Planets ◽  
Planet Formation ◽  
Terrestrial Planet ◽  
The Other ◽  
Terrestrial Planets ◽  
Giant Impacts ◽  
Earth Like Planets ◽  
Jovian Planet

Accretion of terrestrial planets and solid cores of jovian planets is discussed, based on the results of our N-body simulations. Protoplanets accrete from planetesimals through runaway and oligarchic growth until they become isolated. The isolation mass of protoplanets in terrestrial planet region is about 0.2 Earth mass, which suggests that in the final stage of terrestrial planet formation giant impacts between the protoplanets occur. On the other hand, the isolation mass in jovian planet region is about a few to 10 Earth masses, which may be massive enough to form a gas giant. Extending the above arguments to disks with various initial masses, we discuss diversity of planetary systems. We predict that the extrasolar planets so far discovered may correspond to the systems formed from disks with large initial masses and that the other disks with smaller masses, which are the majority of the disks, may form Earth-like planets.

scholarly journals Formation of terrestrial planets in eccentric and inclined giant planet systems

2018 ◽  
Vol 613 ◽  
pp. A59
Author(s):  
Sotiris Sotiriadis ◽  
Anne-Sophie Libert ◽  
Sean N. Raymond
Keyword(s):  
Late Stage ◽  
Outer Part ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Giant Planets ◽  
Terrestrial Planets ◽  
Orbital Parameters ◽  
Resonant Interactions ◽  
Combined Action ◽  
The Impact

Aims. Evidence of mutually inclined planetary orbits has been reported for giant planets in recent years. Here we aim to study the impact of eccentric and inclined massive giant planets on the terrestrial planet formation process, and investigate whether it can possibly lead to the formation of inclined terrestrial planets. Methods. We performed 126 simulations of the late-stage planetary accretion in eccentric and inclined giant planet systems. The physical and orbital parameters of the giant planet systems result from n-body simulations of three giant planets in the late stage of the gas disc, under the combined action of Type II migration and planet-planet scattering. Fourteen two- and three-planet configurations were selected, with diversified masses, semi-major axes (resonant configurations or not), eccentricities, and inclinations (including coplanar systems) at the dispersal of the gas disc. We then followed the gravitational interactions of these systems with an inner disc of planetesimals and embryos (nine runs per system), studying in detail the final configurations of the formed terrestrial planets. Results. In addition to the well-known secular and resonant interactions between the giant planets and the outer part of the disc, giant planets on inclined orbits also strongly excite the planetesimals and embryos in the inner part of the disc through the combined action of nodal resonance and the Lidov–Kozai mechanism. This has deep consequences on the formation of terrestrial planets. While coplanar giant systems harbour several terrestrial planets, generally as massive as the Earth and mainly on low-eccentric and low-inclined orbits, terrestrial planets formed in systems with mutually inclined giant planets are usually fewer, less massive (<0.5 M⊕), and with higher eccentricities and inclinations. This work shows that terrestrial planets can form on stable inclined orbits through the classical accretion theory, even in coplanar giant planet systems emerging from the disc phase.

scholarly journals Future Missions Related to the Determination of the Elemental and Isotopic Composition of Earth, Moon and the Terrestrial Planets

2020 ◽  
Vol 216 (8) ◽  
Author(s):  
Iannis Dandouras ◽  
Michel Blanc ◽  
Luca Fossati ◽  
Mikhail Gerasimov ◽  
Eike W. Guenther ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Noble Gas ◽  
Planetary Science ◽  
Terrestrial Planets ◽  
Planetary Evolution ◽  
Atmospheric Escape ◽  
Open Questions ◽  
Formation History ◽  
Evolutionary Paths

AbstractIn this chapter, we review the contribution of space missions to the determination of the elemental and isotopic composition of Earth, Moon and the terrestrial planets, with special emphasis on currently planned and future missions. We show how these missions are going to significantly contribute to, or sometimes revolutionise, our understanding of planetary evolution, from formation to the possible emergence of life. We start with the Earth, which is a unique habitable body with actual life, and that is strongly related to its atmosphere. The new wave of missions to the Moon is then reviewed, which are going to study its formation history, the structure and dynamics of its tenuous exosphere and the interaction of the Moon’s surface and exosphere with the different sources of plasma and radiation of its environment, including the solar wind and the escaping Earth’s upper atmosphere. Missions to study the noble gas atmospheres of the terrestrial planets, Venus and Mars, are then examined. These missions are expected to trace the evolutionary paths of these two noble gas atmospheres, with a special emphasis on understanding the effect of atmospheric escape on the fate of water. Future missions to these planets will be key to help us establishing a comparative view of the evolution of climates and habitability at Earth, Venus and Mars, one of the most important and challenging open questions of planetary science. Finally, as the detection and characterisation of exoplanets is currently revolutionising the scope of planetary science, we review the missions aiming to characterise the internal structure and the atmospheres of these exoplanets.

scholarly journals Atmospheric mass-loss due to giant impacts: the importance of the thermal component for hydrogen–helium envelopes

2019 ◽  
Vol 485 (3) ◽  
pp. 4454-4463 ◽  
Author(s):  
John B Biersteker ◽  
Hilke E Schlichting
Keyword(s):  
Heat Capacity ◽  
Mass Loss ◽  
Thermal State ◽  
Mechanical Shock ◽  
Partial Explanation ◽  
Giant Impact ◽  
Giant Impacts ◽  
Compositional Diversity ◽  
Atmospheric Loss ◽  
The Impact

ABSTRACT Systems of super-Earths and mini-Neptunes display striking variety in planetary bulk density and composition. Giant impacts are expected to play a role in the formation of many of these worlds. Previous works, focused on the mechanical shock caused by a giant impact, showed that these impacts can eject large fractions of the planetary envelope, offering a partial explanation for the observed compositional diversity. Here, we examine the thermal consequences of giant impacts, and show that the atmospheric loss caused by these effects can significantly exceed that caused by mechanical shocks for hydrogen–helium (H/He) envelopes. During a giant impact, part of the impact energy is converted into thermal energy, heating the rocky core and envelope. We find that the ensuing thermal expansion of the envelope can lead to a period of sustained, rapid mass-loss through a Parker wind, partly or completely eroding the H/He envelope. The degree of atmospheric loss depends on the planet’s orbital distance from its host star and its initial thermal state, and hence age. Close-in planets and younger planets are more susceptible to impact-triggered atmospheric loss. For planets where the heat capacity of the core is much greater than the envelope’s heat capacity (envelope mass fractions ≲4 per cent), the impactor mass required for significant atmospheric removal is Mimp/Mp ∼ μ/μc ∼ 0.1, approximately the ratio of the heat capacities of the envelope and core. Conversely, when the envelope dominates the planet’s heat capacity, complete loss occurs when the impactor mass is comparable to the envelope mass.

scholarly journals The debris disk – terrestrial planet connection

2010 ◽  
Vol 6 (S276) ◽  
pp. 82-88 ◽  
Author(s):  
Sean N. Raymond ◽  
Philip J. Armitage ◽  
Amaya Moro-Martín ◽  
Mark Booth ◽  
Mark C. Wyatt ◽  
...  
Keyword(s):  
Giant Planet ◽  
Terrestrial Planet ◽  
Giant Planets ◽  
Terrestrial Planets ◽  
Debris Disks ◽  
Icy Bodies ◽  
Low Mass ◽  
Infrared Wavelengths ◽  
Dynamical Instabilities ◽  
The Impact

AbstractThe eccentric orbits of the known extrasolar giant planets provide evidence that most planet-forming environments undergo violent dynamical instabilities. Here, we numerically simulate the impact of giant planet instabilities on planetary systems as a whole. We find that populations of inner rocky and outer icy bodies are both shaped by the giant planet dynamics and are naturally correlated. Strong instabilities – those with very eccentric surviving giant planets – completely clear out their inner and outer regions. In contrast, systems with stable or low-mass giant planets form terrestrial planets in their inner regions and outer icy bodies produce dust that is observable as debris disks at mid-infrared wavelengths. Fifteen to twenty percent of old stars are observed to have bright debris disks (at λ ~ 70μm) and we predict that these signpost dynamically calm environments that should contain terrestrial planets.

scholarly journals Forming terrestrial planets and delivering water

2015 ◽  
Vol 11 (A29B) ◽  
pp. 427-430
Author(s):  
Kevin J. Walsh
Keyword(s):  
Planet Formation ◽  
Semimajor Axis ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Terrestrial Planets ◽  
The Earth ◽  
Building Models ◽  
Rich Material

AbstractBuilding models capable of successfully matching the Terrestrial Planet's basic orbital and physical properties has proven difficult. Meanwhile, improved estimates of the nature of water-rich material accreted by the Earth, along with the timing of its delivery, have added even more constraints for models to match. While the outer Asteroid Belt seemingly provides a source for water-rich planetesimals, models that delivered enough of them to the still-forming Terrestrial Planets typically failed on other basic constraints - such as the mass of Mars.Recent models of Terrestrial Planet Formation have explored how the gas-driven migration of the Giant Planets can solve long-standing issues with the Earth/Mars size ratio. This model is forced to reproduce the orbital and taxonomic distribution of bodies in the Asteroid Belt from a much wider range of semimajor axis than previously considered. In doing so, it also provides a mechanism to feed planetesimals from between and beyond the Giant Planet formation region to the still-forming Terrestrial Planets.

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