scholarly journals The Diversity of Extrasolar Terrestrial Planets

2009 ◽  
Vol 5 (S265) ◽  
pp. 399-402
Author(s):  
Jade C. Bond ◽  
Dante S. Lauretta ◽  
David P. O'Brien
Keyword(s):  
Chemical Equilibrium ◽  
Planet Formation ◽  
Planetary Systems ◽  
Solid Material ◽  
Terrestrial Planet ◽  
Building Blocks ◽  
Terrestrial Planets ◽  
Dynamical Models ◽  
Diverse Range ◽  
Host Stars

AbstractExtrasolar planetary host stars are enriched in key planet-building elements. These enrichments have the potential to drastically alter the building blocks available for terrestrial planet formation. Here we report on the combination of dynamical models of late-stage terrestrial planet formation within known extrasolar planetary systems with chemical equilibrium models of the composition of solid material within the disk. This allows us to constrain the bulk elemental composition of extrasolar terrestrial planets. A wide variety of resulting planetary compositions exist, ranging from those that are essentially “Earth-like”, containing metallic Fe and Mg-silicates, to those that are dominated by graphite and SiC. This implies that a diverse range of terrestrial planets are likely to exist within extrasolar planetary systems.

scholarly journals Migration & Extra-solar Terrestrial Planets: Watering the Planets

2012 ◽  
Vol 8 (S293) ◽  
pp. 229-234
Author(s):  
Jade C. Carter-Bond ◽  
David P. O'Brien ◽  
Sean N. Raymond
Keyword(s):  
Chemical Equilibrium ◽  
Formation Process ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Dynamical Models ◽  
Diverse Range ◽  
Refractory Elements ◽  
Planet Migration ◽  
The Impact ◽  
Host Stars

AbstractA diverse range of terrestrial planet compositions is believed to exist within known extrasolar planetary systems, ranging from those that are relatively Earth-like to those that are highly unusual, dominated by species such as refractory elements (Al and Ca) or C (as pure C, TiC and SiC)(Bond et al. 2010b). However, all prior simulations have ignored the impact that giant planet migration during planetary accretion may have on the final terrestrial planetary composition. Here, we combined chemical equilibrium models of the disk around five known planetary host stars (Solar, HD4203, HD19994, HD213240 and Gl777) with dynamical models of terrestrial planet formation incorporating various degrees of giant planet migration. Giant planet migration is found to drastically impact terrestrial planet composition by 1) increasing the amount of Mg-silicate species present in the final body; and 2) dramatically increasing the efficiency and amount of water delivered to the terrestrial bodies during their formation process.

On the possibility of terrestrial planet formation in hot-Jupiter systems

2006 ◽  
Vol 5 (3) ◽  
pp. 199-209 ◽  
Author(s):  
Martyn J. Fogg ◽  
Richard P. Nelson
Keyword(s):  
Planet Formation ◽  
Giant Planet ◽  
Solid Material ◽  
Terrestrial Planet ◽  
Central Star ◽  
Terrestrial Planets ◽  
Hot Jupiters ◽  
Exoplanetary Systems ◽  
Habitable Zones ◽  
Hot Jupiter

About a fifth of the exoplanetary systems that have been discovered contain a so-called hot-Jupiter – a giant planet orbiting within 0.1 AU of the central star. Since these stars are typically of the F/G spectral type, the orbits of any terrestrial planets in their habitable zones at ~1 AU should be dynamically stable. However, because hot-Jupiters are thought to have formed in the outer regions of a protoplanetary disc, and to have then migrated through the terrestrial planet zone to their final location, it is uncertain whether terrestrial planets can actually grow and be retained in these systems. In this paper we review attempts to answer this question. Initial speculations, based on the assumption that migrating giant planets will clear planet-forming material from their swept zone, all concluded that hot-Jupiter systems should lack terrestrial planets. We show that this assumption may be incorrect, for when terrestrial planet formation and giant planet migration are simulated simultaneously, abundant solid material is predicted to remain from which terrestrial planet growth can resume.

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.

scholarly journals Terrestrial planet formation in extra-solar planetary systems

2007 ◽  
Vol 3 (S249) ◽  
pp. 233-250 ◽  
Author(s):  
Sean N. Raymond
Keyword(s):  
Final Stage ◽  
Planet Formation ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Circumstellar Disks ◽  
Giant Planets ◽  
Terrestrial Planets ◽  
Low Mass Stars ◽  
Low Mass ◽  
Rocky Planets

AbstractTerrestrial planets form in a series of dynamical steps from the solid component of circumstellar disks. First, km-sized planetesimals form likely via a combination of sticky collisions, turbulent concentration of solids, and gravitational collapse from micron-sized dust grains in the thin disk midplane. Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also called “planetary embryos”. Finally, full-sized terrestrial planets accrete from protoplanets and planetesimals. This final stage of accretion lasts about 10-100 Myr and is strongly affected by gravitational perturbations from any gas giant planets, which are constrained to form more quickly, during the 1-10 Myr lifetime of the gaseous component of the disk. It is during this final stage that the bulk compositions and volatile (e.g., water) contents of terrestrial planets are set, depending on their feeding zones and the amount of radial mixing that occurs. The main factors that influence terrestrial planet formation are the mass and surface density profile of the disk, and the perturbations from giant planets and binary companions if they exist. Simple accretion models predicts that low-mass stars should form small, dry planets in their habitable zones. The migration of a giant planet through a disk of rocky bodies does not completely impede terrestrial planet growth. Rather, “hot Jupiter” systems are likely to also contain exterior, very water-rich Earth-like planets, and also “hot Earths”, very close-in rocky planets. Roughly one third of the known systems of extra-solar (giant) planets could allow a terrestrial planet to form in the habitable zone.

scholarly journals N-body Simulations of Planet Formation

2003 ◽  
Vol 208 ◽  
pp. 25-35 ◽  
Author(s):  
Shigeru Ida ◽  
Eiichiro Kokubo ◽  
Junko Kominami
Keyword(s):  
Final Stage ◽  
Planet Formation ◽  
Planetary Systems ◽  
Terrestrial Planet ◽  
The Other ◽  
Other Hand ◽  
Giant Impacts ◽  
Gas Accretion

Accretion from many small planetesimals to planets is reviewed. Solid protoplanets accrete through runaway and oligarchic growth until they become isolated. The isolation mass of protoplanets in terrestrial planet region is about 0.1-0.2 Earth mass, which suggests giant impacts among the protoplanets in the final stage of terrestrial planet formation. On the other hand, the isolation mass in Jupiter's and Saturn's orbits is about a few to 5 Earth masses, which may be massive enough to trigger gas accretion onto the cores. The isolation mass in Uranus and Neptune's orbits is as large as their present cores. Extending the above arguments to extrasolar planetary systems that are formed from disks with various initial masses, we also discuss diversity of extrasolar planetary systems.

scholarly journals Lunar and terrestrial planet formation in the Grand Tack scenario

2014 ◽  
Vol 372 (2024) ◽  
pp. 20130174 ◽  
Author(s):  
S. A. Jacobson ◽  
A. Morbidelli
Keyword(s):  
Total Mass ◽  
Planet Formation ◽  
Terrestrial Planet ◽  
Terrestrial Planets ◽  
The Moon ◽  
Giant Impact ◽  
Modal Mass ◽  
The Individual ◽  
Impact Phase ◽  
Geochemical Constraints

We present conclusions from a large number of N -body simulations of the giant impact phase of terrestrial planet formation. We focus on new results obtained from the recently proposed Grand Tack model, which couples the gas-driven migration of giant planets to the accretion of the terrestrial planets. The giant impact phase follows the oligarchic growth phase, which builds a bi-modal mass distribution within the disc of embryos and planetesimals. By varying the ratio of the total mass in the embryo population to the total mass in the planetesimal population and the mass of the individual embryos, we explore how different disc conditions control the final planets. The total mass ratio of embryos to planetesimals controls the timing of the last giant (Moon-forming) impact and its violence. The initial embryo mass sets the size of the lunar impactor and the growth rate of Mars. After comparing our simulated outcomes with the actual orbits of the terrestrial planets (angular momentum deficit, mass concentration) and taking into account independent geochemical constraints on the mass accreted by the Earth after the Moon-forming event and on the time scale for the growth of Mars, we conclude that the protoplanetary disc at the beginning of the giant impact phase must have had most of its mass in Mars-sized embryos and only a small fraction of the total disc mass in the planetesimal population. From this, we infer that the Moon-forming event occurred between approximately 60 and approximately 130 Myr after the formation of the first solids and was caused most likely by an object with a mass similar to that of Mars.

scholarly journals Can narrow discs in the inner Solar system explain the four terrestrial planets?

2020 ◽  
Vol 496 (3) ◽  
pp. 3688-3699 ◽  
Author(s):  
Patryk Sofia Lykawka
Keyword(s):  
Solar System ◽  
Planet Formation ◽  
Terrestrial Planet ◽  
Giant Planets ◽  
System Model ◽  
Terrestrial Planets ◽  
P System ◽  
Orbital Mass ◽  
System A ◽  
System 2

ABSTRACT A successful Solar system model must reproduce the four terrestrial planets. Here, we focus on (1) the likelihood of forming Mercury and the four terrestrial planets in the same system (a 4-P system); (2) the orbital properties and masses of each terrestrial planet; and (3) the timing of Earth’s last giant impact and the mass accreted by our planet thereafter. Addressing these constraints, we performed 450 N-body simulations of terrestrial planet formation based on narrow protoplanetary discs with mass confined to 0.7–1.0 au. We identified 164 analogue systems, but only 24 systems contained Mercury analogues, and eight systems were 4-P ones. We found that narrow discs containing a small number of embryos with individual masses comparable to that of Mars and the giant planets on their current orbits yielded the best prospects for satisfying those constraints. However, serious shortcomings remain. The formation of Mercury analogues and 4-P systems was too inefficient (5 per cent and 2 per cent, respectively), and most Venus-to-Earth analogue mass ratios were incorrect. Mercury and Venus analogues also formed too close to each other (∼0.15–0.21 au) compared to reality (0.34 au). Similarly, the mutual distances between the Venus and Earth analogues were greater than those observed (0.34 versus 0.28 au). Furthermore, the Venus–Earth pair was not reproduced in orbital-mass space statistically. Overall, our results suggest serious problems with using narrow discs to explain the inner Solar system. In particular, the formation of Mercury remains an outstanding problem for terrestrial planet formation models.

scholarly journals Terrestrial planet formation in low-mass disks: dependence with initial conditions

2014 ◽  
Vol 9 (S310) ◽  
pp. 218-219
Author(s):  
M. P. Ronco ◽  
G. C. de Elía ◽  
O. M. Guilera
Keyword(s):  
Gas Phase ◽  
Analytical Model ◽  
Ad Hoc ◽  
Planet Formation ◽  
Initial Conditions ◽  
Planetary Systems ◽  
Terrestrial Planet ◽  
Initial Distribution ◽  
Protoplanetary Disk ◽  
Low Mass

AbstractIn general, most of the studies of terrestrial-type planet formation typically use ad hoc initial conditions. In this work we improved the initial conditions described in Ronco & de Elía (2014) starting with a semi-analytical model wich simulates the evolution of the protoplanetary disk during the gas phase. The results of the semi-analytical model are then used as initial conditions for the N-body simulations. We show that the planetary systems considered are not sensitive to the particular initial distribution of embryos and planetesimals and thus, the results are globally similar to those found in the previous work.

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.

Terrestrial planet accretion constrained by isotopes: Implications for Earth-like habitats

2021 ◽  
Author(s):  
Helmut Lammer ◽  
Manuel Scherf ◽  
Nikolai V. Erkaev
Keyword(s):  
Sea Water ◽  
Terrestrial Planet ◽  
Building Blocks ◽  
Habitable Zone ◽  
Isotopic Data ◽  
Habitable Zones ◽  
Siderophile Elements ◽  
The Right ◽  
Host Stars ◽  
Planet Accretion

<p>Here we discuss terrestrial planet formation by using Earth and our knowledge from various isotope data such as <sup>182</sup>Hf-<sup>182</sup>W, U-Pb, lithophile-siderophile elements, atmospheric <sup>36</sup>Ar/<sup>38</sup>Ar, <sup>20</sup>Ne/<sup>22</sup>Ne, <sup>36</sup>Ar/<sup>22</sup>Ne isotope ratios, the expected solar <sup>3</sup>He abundance in Earth’s deep mantle and Earth’s D/H sea water ratios as an example. By analyzing the available isotopic data one finds that, the bulk of Earth’s mass most likely accreted within 10 to 30 million years after the formation of the solar system. Proto-Earth most likely accreted a mass of 0.5 to 0.6 <em>M</em><sub>Earth</sub> during the disk lifetime of 3 to 4.5 million years and the rest after the disk evaporated (see also Lammer et al. 2021; DOI: 10.1007/s11214-020-00778-4). We also show that particular accretion scenarios of involved planetary building blocks, large planetesimals and planetary embryos that lose also volatiles and moderate volatile rock-forming elements such as the radioactive decaying isotope <sup>40</sup>K determine if a terrestrial planet in a habitable zone of a Sun-like star later evolves to an Earth-like habitat or not. Our findings indicate that one can expect a large diversity of exoplanets with the size and mass of Earth inside habitable zones of their host stars but only a tiny number may have formed to the right conditions that they could potentially evolve to an Earth-like habitat. Finally, we also discuss how future ground- and space-based telescopes that can characterize atmospheres of terrestrial exoplanets can be used to validate this hypothesis.   </p>

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