scholarly journals Formation of exoplanetary satellites by pull-down capture

2019 ◽  
Vol 5 (10) ◽  
pp. eaaw8665 ◽  
Author(s):  
Bradley M. S. Hansen
Keyword(s):  
Initial Conditions ◽  
Giant Planet ◽  
Giant Planets ◽  
Capture Process ◽  
Satellite Formation ◽  
Large Size ◽  
Numerical Integrations ◽  
The Stability ◽  
Gaseous Envelope ◽  
Original Configuration

The large size and wide orbit of the recently announced exomoon candidate Kepler-1625b-i are hard to explain within traditional theories of satellite formation. We show that these properties can be reproduced if the satellite began as a circumstellar co-orbital body with the original core of the giant planet Kepler-1625b. This body was then drawn down into a circumplanetary orbit during the rapid accretion of the giant planet gaseous envelope, a process termed “pull-down capture.” Our numerical integrations demonstrate the stability of the original configuration and the capture process. In this model, the exomoon Kepler-1625b-i is the protocore of a giant planet that never accreted a substantial gas envelope. Different initial conditions can give rise to capture into other co-orbital configurations, motivating the search for Trojan-like companions to this and other giant planets.

scholarly journals Fingerprints of giant planets in the composition of solar twins

2020 ◽  
Vol 493 (4) ◽  
pp. 5079-5088 ◽  
Author(s):  
Richard A Booth ◽  
James E Owen
Keyword(s):  
Refractory Material ◽  
Planet Formation ◽  
Initial Conditions ◽  
Giant Planet ◽  
Planetary Systems ◽  
Giant Planets ◽  
The Sun ◽  
Evolutionary Models ◽  
Refractory Elements ◽  
Protoplanetary Discs

ABSTRACT The Sun shows a ∼10 per cent depletion in refractory elements relative to nearby solar twins. It has been suggested that this depletion is a signpost of planet formation. The exoplanet statistics are now good enough to show that the origin of this depletion does not arise from the sequestration of refractory material inside the planets themselves. This conclusion arises because most sun-like stars host close-in planetary systems that are on average more massive than the Sun’s. Using evolutionary models for the protoplanetary discs that surrounded the young Sun and solar twins, we demonstrate that the origin of the depletion likely arises due to the trapping of dust exterior to the orbit of a forming giant planet. In this scenario, a forming giant planet opens a gap in the gas disc, creating a pressure trap. If the planet forms early enough, while the disc is still massive, the planet can trap ≳100 M⊕ of dust exterior to its orbit, preventing the dust from accreting on to the star in contrast to the gas. Forming giant planets can create refractory depletions of $\sim 5{-}15{{\ \rm per\ cent}}$, with the larger values occurring for initial conditions that favour giant planet formation (e.g. more massive discs that live longer). The incidence of solar twins that show refractory depletion matches both the occurrence of giant planets discovered in exoplanet surveys and ‘transition’ discs that show similar depletion patterns in the material that is accreting on to the star.

scholarly journals Short-term stability of particles in the WD J0914+1914 white dwarf planetary system

2020 ◽  
Vol 497 (4) ◽  
pp. 5171-5181
Author(s):  
Euaggelos E Zotos ◽  
Dimitri Veras ◽  
Tareq Saeed ◽  
Luciano A Darriba
Keyword(s):  
Phase Space ◽  
White Dwarf ◽  
Planetary System ◽  
Outer Boundary ◽  
Giant Planet ◽  
Short Term ◽  
Numerical Integrations ◽  
Stellar Photosphere ◽  
The Stability ◽  
Do So

ABSTRACT Nearly all known white dwarf planetary systems contain detectable rocky debris in the stellar photosphere. A glaring exception is the young and still evolving white dwarf WD J0914+1914, which instead harbours a giant planet and a disc of pure gas. The stability boundaries of this disc and the future prospects for this white dwarf to be polluted with rocks depend upon the mass and orbit of the planet, which are only weakly constrained. Here, we combine an ensemble of plausible planet orbits and masses to determine where observers should currently expect to find the outer boundary of the gas disc. We do so by performing a sweep of the entire plausible phase space with short-term numerical integrations. We also demonstrate that particle-star collisional trajectories, which would lead to the (unseen) signature of rocky metal pollution, occupy only a small fraction of the phase space, mostly limited to particle eccentricities above 0.75. Our analysis reveals that a highly inflated planet on a near-circular orbit is the type of planet which is most consistent with the current observations.

scholarly journals Puzzling out the coexistence of terrestrial planets and giant exoplanets

2018 ◽  
Vol 615 ◽  
pp. A60 ◽  
Author(s):  
Kyriaki I. Antoniadou ◽  
Anne-Sophie Libert
Keyword(s):  
Periodic Orbits ◽  
Giant Planet ◽  
Terrestrial Planet ◽  
Major Axis ◽  
Giant Planets ◽  
Outer Planet ◽  
Semi Major Axis ◽  
Fast Lyapunov Indicator ◽  
The Stability ◽  
Three Body

Aims. Hundreds of giant planets have been discovered so far and the quest of exo-Earths in giant planet systems has become intriguing. In this work, we aim to address the question of the possible long-term coexistence of a terrestrial companion on an orbit interior to a giant planet, and explore the extent of the stability regions for both non-resonant and resonant configurations. Methods. Our study focuses on the restricted three-body problem, where an inner terrestrial planet (massless body) moves under the gravitational attraction of a star and an outer massive planet on a circular or elliptic orbit. Using the detrended fast Lyapunov indicator as a chaotic indicator, we constructed maps of dynamical stability by varying both the eccentricity of the outer giant planet and the semi-major axis of the inner terrestrial planet, and identify the boundaries of the stability domains. Guided by the computation of families of periodic orbits, the phase space is unravelled by meticulously chosen stable periodic orbits, which buttress the stability domains. Results. We provide all possible stability domains for coplanar symmetric configurations and show that a terrestrial planet, either in mean-motion resonance or not, can coexist with a giant planet, when the latter moves on either a circular or an (even highly) eccentric orbit. New families of symmetric and asymmetric periodic orbits are presented for the 2/1 resonance. It is shown that an inner terrestrial planet can survive long time spans with a giant eccentric outer planet on resonant symmetric orbits, even when both orbits are highly eccentric. For 22 detected single-planet systems consisting of a giant planet with high eccentricity, we discuss the possible existence of a terrestrial planet. This study is particularly suitable for the research of companions among the detected systems with giant planets, and could assist with refining observational data.

scholarly journals Formation of the Giant Planets

1981 ◽  
Vol 93 ◽  
pp. 133-134
Author(s):  
Hiroshi Mizuno
Keyword(s):  
Radiative Transfer ◽  
Solar Nebula ◽  
Giant Planet ◽  
Giant Planets ◽  
Core Mass ◽  
The Core ◽  
Gaseous Envelope

The structure of a gaseous envelope surrounding a icy/rocky core is studied in consideration of radiative transfer. It is found that when the core grows beyond a critical core mass, the envelope cannot be in equilibrium and collapses onto the core to form a proto-giant planet. The results are as follows (for details, see Mizuno 1980).1) The critical core mass is smaller than that estimated by Perri and Cameron (1974) and Mizuno, Nakazawa and Hayashi (1978). 2) When the grain opacity in the envelope varies from 0 to 1 cm2/g, the critical core mass changes from ~2 to ~12 Earth's masses. 3) The critical core mass is independent of the region in the solar nebula.These are due to the existence of the radiative region in the envelope.

scholarly journals Pebbles versus planetesimals

2020 ◽  
Vol 640 ◽  
pp. A21 ◽  
Author(s):  
N. Brügger ◽  
R. Burn ◽  
G. A. L. Coleman ◽  
Y. Alibert ◽  
W. Benz
Keyword(s):  
Planet Formation ◽  
Initial Conditions ◽  
Giant Planet ◽  
Mass Range ◽  
Giant Planets ◽  
The Other ◽  
Type I ◽  
Core Mass ◽  
Accretion Model ◽  
The Impact

Context. In the core accretion scenario of giant planet formation, a massive core forms first and then accretes a gaseous envelope. In the discussion of how this core forms, some divergences appear. The first scenarios of planet formation predict the accretion of kilometre-sized bodies called planetesimals, while more recent works suggest growth by the accretion of pebbles, which are centimetre-sized objects. Aims. These two accretion models are often discussed separately and our aim here is to compare the outcomes of the two models with identical initial conditions. Methods. The comparison is done using two distinct codes, one that computes the planetesimal accretion and the other the pebble accretion. All the other components of the simulated planet growth are computed identically in the two models: the disc, the accretion of gas, and the migration. Using a population synthesis approach, we compare planet simulations and study the impact of the two solid accretion models, focusing on the formation of single planets. Results. We find that the outcomes of the populations are strongly influenced by the accretion model. The planetesimal model predicts the formation of more giant planets, while the pebble accretion model forms more super-Earth-mass planets. This is due to the pebble isolation mass (Miso) concept, which prevents planets formed by pebble accretion to accrete gas efficiently before reaching Miso. This translates into a population of planets that are not heavy enough to accrete a consequent envelope, but that are in a mass range where type I migration is very efficient. We also find higher gas mass fractions for a given core mass for the pebble model compared to the planetesimal model, caused by luminosity differences. This also implies planets with lower densities, which could be confirmed observationally. Conclusions. We conclude that the two models produce different outputs. Focusing on giant planets, the sensitivity of their formation differs: for the pebble accretion model, the time at which the embryos are formed and the period over which solids are accreted strongly impact the results, while the population of giant planets formed by planetesimal accretion depends on the planetesimal size and on the splitting in the amount of solids available to form planetesimals.

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.

A PHYSICAL INTERPRETATION OF MELNIKOV’S METHOD

1992 ◽  
Vol 02 (01) ◽  
pp. 1-9 ◽  
Author(s):  
YOHANNES KETEMA
Keyword(s):  
Physical Interpretation ◽  
Poincaré Map ◽  
Initial Conditions ◽  
Homoclinic Orbits ◽  
Poincare Map ◽  
Stable And Unstable Manifolds ◽  
Melnikov's Method ◽  
Melnikov’S Method ◽  
Sensitive Dependence ◽  
The Stability

This paper is concerned with analyzing Melnikov’s method in terms of the flow generated by a vector field in contrast to the approach based on the Poincare map and giving a physical interpretation of the method. It is shown that the direct implication of a transverse crossing between the stable and unstable manifolds to a saddle point of the Poincare map is the existence of two distinct preserved homoclinic orbits of the continuous time system. The stability of these orbits and their role in the phenomenon of sensitive dependence on initial conditions is discussed and a physical example is given.

Parallel-Process (Simultaneous) Machining and its Stability

1999 ◽  
Author(s):  
O. Burak Ozdoganlar ◽  
William J. Endres
Keyword(s):  
Initial Conditions ◽  
General System ◽  
Parallel Process ◽  
Analytical Stability ◽  
Multiple Processes ◽  
Or Practice ◽  
Machining System ◽  
Eigenvector Analysis ◽  
The Stability ◽  
Machining Operations

Abstract This paper presents a mathematical perspective, to complement the intuitive or practice-oriented perspective, to classifying machining operations as parallel-process (simultaneous) or single-process in nature. Illustrative scenarios are provided to demonstrate how these two perspectives may lead in different situations to the same or different conclusions regarding process parallelism. A model representation of a general parallel-process machining system is presented, based on which the general parallel-process stability eigenvalue problem is formulated. For a special simplified case of the general system, analytical methods are employed to derive a fully analytical stability solution. Thorough study of this solution through eigenvector analysis sheds light on some fundamental phenomena of parallel-process machining stability, such as dependence of the stability solution on phasing of the initial conditions (disturbances). This establishes the importance, when employing numerical time-domain simulation for such analyses, of specifying initial conditions for the multiple processes to be arbitrarily phased so that correct results are achieved across all spindle speeds.

scholarly journals Full exploration of the giant planet population around β Pictoris

2018 ◽  
Vol 612 ◽  
pp. A108 ◽  
Author(s):  
A.-M. Lagrange ◽  
M. Keppler ◽  
N. Meunier ◽  
J. Lannier ◽  
H. Beust ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Giant Planet ◽  
Young Stars ◽  
Giant Planets ◽  
Close Orbit ◽  
Wide Range ◽  
Detection Probabilities ◽  
Solar Type ◽  
Formation And Evolution ◽  
The One

Context. The search for extrasolar planets has been limited so far to close orbit (typ. ≤5 au) planets around mature solar-type stars on the one hand, and to planets on wide orbits (≥10 au) around young stars on the other hand. To get a better view of the full giant planet population, we have started a survey to search for giant planets around a sample of carefully selected young stars. Aims. This paper aims at exploring the giant planet population around one of our targets, β Pictoris, over a wide range of separations. With a disk and a planet already known, the β Pictoris system is indeed a very precious system for studies of planetary formation and evolution, as well as of planet–disk interactions. Methods. We analyse more than 2000 HARPS high-resolution spectra taken over 13 years as well as NaCo images recorded between 2003 and 2016. We combine these data to compute the detection probabilities of planets throughout the disk, from a fraction of au to a few dozen au. Results. We exclude the presence of planets more massive than 3 MJup closer than 1 au and further than 10 au, with a 90% probability. 15+ MJup companions are excluded throughout the disk except between 3 and 5 au with a 90% probability. In this region, we exclude companions with masses larger than 18 (resp. 30) MJup with probabilities of 60 (resp. 90) %.

scholarly journals Investigating the young solar system analog HD 95086

2018 ◽  
Vol 617 ◽  
pp. A76 ◽  
Author(s):  
G. Chauvin ◽  
R. Gratton ◽  
M. Bonnefoy ◽  
A.-M. Lagrange ◽  
J. de Boer ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Giant Planets ◽  
Dual Band ◽  
Spectral Energy ◽  
Semi Major Axis ◽  
Integral Field Spectrograph

Context. HD 95086 (A8V, 17 Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4–5 MJup have been directly imaged. Aims. Our study aims to characterize the global architecture of this young system using the combination of radial velocity and direct imaging observations. We want to characterize the physical and orbital properties of HD 95086 b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. Methods. We used HARPS at the ESO 3.6 m telescope to monitor the radial velocity of HD 95086 over two years and investigate the existence of giant planets at less than 3 au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10 au at six epochs between 2015 and 2017. Results. We do not detect additional giant planets around HD 95086. We identify the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD 95086 b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7–L9 dwarf spectral templates. The extremely red 1–4 μm spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet’s orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e = 0.2+0.3−0.2, with a semi-major axis ~52 au corresponding to orbital periods of ~288 yr and an inclination that peaks at i = 141°, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300 au, consistent in radial extent with recent ALMA 1.3 mm resolved observations.

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