scholarly journals Tidal disruption versus planetesimal collisions as possible origins for the dispersing dust cloud around Fomalhaut

2020 ◽  
Vol 640 ◽  
pp. A93
Author(s):  
Markus Janson ◽  
Yanqin Wu ◽  
Gianni Cataldi ◽  
Alexis Brandeker
Keyword(s):  
Dust Cloud ◽  
Giant Planet ◽  
Major Axis ◽  
Giant Planets ◽  
Recent Analysis ◽  
Interaction Cross Section ◽  
Semi Major Axis ◽  
Tidal Disruption ◽  
Specific Prediction ◽  
Dust Ring

Recent analysis suggests that the faint optical point source observed around Fomalhaut from 2004–2014 (Fomalhaut b) is gradually fading and expanding, supporting the case that it may be a dispersing dust cloud resulting from the sudden disruption of a planetesimal. These types of disruptions may arise from catastrophic collisions of planetesimals, which are perturbed from their original orbits in the Fomalhaut dust ring by nearby giant planets. However, disruptions can also occur when the planetesimals pass within the tidal disruption field of the planet(s) that perturbed them in the first place, similar to the Shoemaker-Levy event observed in the Solar System. Given that a gravitationally focusing giant planet has a much larger interaction cross-section than a planetesimal, tidal disruption events can match or outnumber planetesimal collision events in realistic regions of parameter space. Intriguingly, the Fomalhaut dust cloud offers an opportunity to directly distinguish between these scenarios. A tidal disruption scenario leads to a very specific prediction of ephemerides for the planet causing the event. At a most probable mass of 66 M⊕, a semi-major axis of 117 AU, and a system age of 400–500 Myr, this planet would be readily detectable with the James Webb Space Telescope. The presence or absence of this planet at the specific, predicted position is therefore a distinctive indicator of whether the dispersing cloud originated from a collision of two planetesimals or from the disruption of a planetesimal in the tidal field of a giant planet.

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 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.

scholarly journals SOPHIE velocimetry of Kepler transit candidates

2018 ◽  
Vol 615 ◽  
pp. A90 ◽  
Author(s):  
J. M. Almenara ◽  
R. F. Díaz ◽  
G. Hébrard ◽  
R. Mardling ◽  
C. Damiani ◽  
...  
Keyword(s):  
Planetary System ◽  
Major Axis ◽  
Giant Planets ◽  
Eccentric Orbit ◽  
Semi Major Axis ◽  
Hot Jupiters ◽  
Timing Data ◽  
Single Host ◽  
Velocity Information ◽  
The Masses

Kepler-419 is a planetary system discovered by the Kepler photometry which is known to harbour two massive giant planets: an inner 3 MJ transiting planet with a 69.8-day period, highly eccentric orbit, and an outer 7.5 MJ non-transiting planet predicted from the transit-timing variations (TTVs) of the inner planet b to have a 675-day period, moderately eccentric orbit. Here we present new radial velocity (RV) measurements secured over more than two years with the SOPHIE spectrograph, where both planets are clearly detected. The RV data is modelled together with the Kepler photometry using a photodynamical model. The inclusion of velocity information breaks the MR−3 degeneracy inherent in timing data alone, allowing us to measure the absolute stellar and planetary radii and masses. With uncertainties of 12 and 13% for the stellar and inner planet radii, and 35, 24, and 35% for the masses of the star, planet b, and planet c, respectively, these measurements are the most precise to date for a single host star system using this technique. The transiting planet mass is determined at better precision than the star mass. This shows that modelling the radial velocities and the light curve together in systems of dynamically interacting planets provides a way of characterising both the star and the planets without being limited by knowledge of the star. On the other hand, the period ratio and eccentricities place the Kepler-419 system in a sweet spot; had around twice as many transits been observed, the mass of the transiting planet could have been measured using its own TTVs. Finally, the origin of the Kepler-419 system is discussed. We show that the system is near a coplanar high-eccentricity secular fixed point, related to the alignment of the orbits, which has prevented the inner orbit from circularising. For most other relative apsidal orientations, planet b’s orbit would be circular with a semi-major axis of 0.03 au. This suggests a mechanism for forming hot Jupiters in multiplanetary systems without the need of high mutual inclinations.

scholarly journals Mapping the Distributions of Exoplanet Populations with NICI and GPI

2015 ◽  
Vol 10 (S314) ◽  
pp. 220-225
Author(s):  
Eric L. Nielsen ◽  
Michael C. Liu ◽  
Zahed Wahhaj ◽  
Beth A. Biller ◽  
Thomas L. Hayward ◽  
...  
Keyword(s):  
Low Frequency ◽  
Major Axis ◽  
Giant Planets ◽  
Direct Imaging ◽  
Semi Major Axis ◽  
Solar Systems ◽  
Test Models ◽  
Nearby Stars ◽  
Formation And Evolution ◽  
Band Contrast

AbstractWhile more and more long-period giant planets are discovered by direct imaging, the distribution of planets at these separations (≳5 AU) has remained largely uncertain, especially compared to planets in the inner regions of solar systems probed by RV and transit techniques. The low frequency, the detection challenges, and heterogeneous samples make determining the mass and orbit distributions of directly imaged planets at the end of a survey difficult. By utilizing Monte Carlo methods that incorporate the age, distance, and spectral type of each target, we can use all stars in the survey, not just those with detected planets, to learn about the underlying population. We have produced upper limits and direct measurements of the frequency of these planets with the most recent generation of direct imaging surveys. The Gemini NICI Planet-Finding Campaign observed 220 young, nearby stars at a median H-band contrast of 14.5 magnitudes at 1”, representing the largest, deepest search for exoplanets by the completion of the survey. The Gemini Planet Imager Exoplanet Survey is in the process of surveying 600 stars, pushing these contrasts to a few tenths of an arcsecond from the star. With the advent of large surveys (many hundreds of stars) using advanced planet-imagers we gain the ability to move beyond measuring the frequency of wide-separation giant planets and to simultaneously determine the distribution as a function of planet mass, semi-major axis, and stellar mass, and so directly test models of planet formation and evolution.

scholarly journals Survival rates of planets in open clusters: the Pleiades, Hyades, and Praesepe clusters

2019 ◽  
Vol 624 ◽  
pp. A110 ◽  
Author(s):  
M. S. Fujii ◽  
Y. Hori
Keyword(s):  
Open Cluster ◽  
Survival Rates ◽  
Giant Planet ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Major Axis ◽  
Open Clusters ◽  
Semi Major Axis ◽  
Embedded Clusters ◽  
Host Stars

Context. In clustered environments, stellar encounters can liberate planets from their host stars via close encounters. Although the detection probability of planets suggests that the planet population in open clusters resembles that in the field, only a few dozen planet-hosting stars have been discovered in open clusters. Aims. We explore the survival rates of planets against stellar encounters in open clusters similar to the Pleiades, Hyades, and Praesepe and embedded clusters. Methods. We performed a series of N-body simulations of high-density and low-density open clusters, open clusters that grow via mergers of subclusters, and embedded clusters. We semi-analytically calculated the survival rate of planets in star clusters up to ~1 Gyr using relative velocities, masses, and impact parameters of intruding stars. Results. Less than 1.5% of close-in planets within 1 AU and at most 7% of planets with 1–10 AU are ejected by stellar encounters in clustered environments after the dynamical evolution of star clusters. If a planet population from 0.01–100 AU in an open cluster initially follows the probability distribution function of exoplanets with semi-major axis (ap) between 0.03 and 3 AU in the field discovered by RV surveys (∝ ap−0.6), the PDF of surviving planets beyond ~10 AU in open clusters can be slightly modified to ∝ ap−0.76. The production rate of free-floating planets (FFPs) per star is 0.0096–0.18, where we have assumed that all the stars initially have one giant planet with a mass of 1–13 MJup in a circular orbit. The expected frequency of FFPs is compatible with the upper limit on that of FFPs indicated by recent microlensing surveys. Our survival rates of planets in open clusters suggest that planets within 10 AU around FGKM-type stars are rich in relatively-young (≲10–100 Myr for open clusters and ~1–10 Myr for embedded clusters), less massive open clusters, which are promising targets for planet searches.

scholarly journals PLANETARY MIGRATION IN EVOLVING PLANETESIMAL DISKS

2003 ◽  
Vol 12 (08) ◽  
pp. 1399-1414 ◽  
Author(s):  
İ. SAFFET YEŞİLYURT ◽  
E. NİHAL ERCAN ◽  
A. DEL POPOLO
Keyword(s):  
Accretion Disks ◽  
Migration Rate ◽  
Major Axis ◽  
Solid Particles ◽  
Giant Planets ◽  
Semi Major Axis ◽  
Density Profiles ◽  
Disk Model ◽  
Characteristic Radius ◽  
Planetary Migration

In the current paper, we further improved the model for the migration of planets introduced and extended to time-dependent planetesimal accretion disks by Del Popolo. In the current study, the assumption of Del Popolo, that the surface density in planetesimals is proportional to that of gas, is relaxed. In order to obtain the evolution of planetesimal density, we use a method developed by Stepinski and Valageas which is able to simultaneously follow the evolution of gas and solid particles for up to 107 years. Then, the disk model is coupled to migration model introduced by Del Popolo in order to obtain the migration rate of the planet in the planetesimal. We find that the properties of solids known to exist in protoplanetary systems, together with reasonable density profiles for the disk, lead to a characteristic radius in the range 0.03–0.2 AU for the final semi-major axis of the giant planet.Hence our model can explain the properties of discovered extrasolar giant planets.

scholarly journals Planetary migration in gaseous protoplanetary disks

2007 ◽  
Vol 3 (S249) ◽  
pp. 331-346
Author(s):  
Frédéric S. Masset
Keyword(s):  
Major Axis ◽  
Giant Planets ◽  
Type I ◽  
Type Ii ◽  
Orbital Elements ◽  
Intermediate Mass ◽  
Semi Major Axis ◽  
Low Mass ◽  
Planetary Migration ◽  
Different Parts

AbstractTides come from the fact that different parts of a system do not fall in exactly the same way in a non-uniform gravity field. In the case of a protoplanetary disk perturbed by an orbiting, prograde protoplanet, the protoplanet tides raise a wake in the disk which causes the orbital elements of the planet to change over time. The most spectacular result of this process is a change in the protoplanet's semi-major axis, which can decrease by orders of magnitude on timescales shorter than the disk lifetime. This drift in the semi-major axis is called planetary migration. In a first part, we describe how the planet and disk exchange angular momentum and energy at the Lindblad and corotation resonances. Next we review the various types of planetary migration that have so far been contemplated: type I migration, which corresponds to low-mass planets (less than a few Earth masses) triggering a linear disk response; type II migration, which corresponds to massive planets (typically at least one Jupiter mass) that open up a gap in the disk; “runaway” or type III migration, which corresponds to sub-giant planets that orbit in massive disks; and stochastic or diffusive migration, which is the migration mode of low- or intermediate-mass planets embedded in turbulent disks. Lastly, we present some recent results in the field of planetary migration.

scholarly journals The origin of the high metallicity of close-in giant exoplanets

2020 ◽  
Vol 633 ◽  
pp. A33 ◽  
Author(s):  
Sho Shibata ◽  
Ravit Helled ◽  
Masahiro Ikoma
Keyword(s):  
Giant Planet ◽  
Major Axis ◽  
Limited Range ◽  
Heavy Elements ◽  
Semi Major Axis ◽  
Dynamical Simulations ◽  
Gas Accretion ◽  
High Metallicity ◽  
Gas Drag

Context. Recent studies suggest that in comparison to their host star, many giant exoplanets are highly enriched with heavy elements and can contain several tens of Earth masses of heavy elements or more. Such enrichment is considered to have been delivered by the accretion of planetesimals in late formation stages. Previous dynamical simulations, however, have shown that planets cannot accrete such high masses of heavy elements through “in situ” planetesimal accretion. Aims. We investigate whether a giant planet migrating inward can capture planetesimals efficiently enough to significantly increase its metallicity. Methods. We performed orbital integrations of a migrating giant planet and planetesimals in a protoplanetary gas disc to infer the planetesimal mass that is accreted by the planet. Results. We find that the two shepherding processes of mean motion resonance trapping and aerodynamic gas drag inhibit the planetesimal capture of a migrating planet. However, the amplified libration allows the highly-excited planetesimals in the resonances to escape from the resonance trap and to be accreted by the planet. Consequently, we show that a migrating giant planet captures planetesimals with total mass of several tens of Earth masses if the planet forms at a few tens of AU in a relatively massive disc. We also find that planetesimal capture occurs efficiently in a limited range of semi-major axis and that the total captured planetesimal mass increases with increasing migration distances. Our results have important implications for understanding the relation between giant planet metallicity and mass, as we suggest that it reflects the formation location of the planet – or more precisely, the location where runaway gas accretion occurred. We also suggest the observed metal-rich close-in Jupiters migrated to their present locations from afar, where they had initially formed.

Dynamics of Tidal Disruption Events: Statistical Properties

2020 ◽  
Author(s):  
Amir Weissbein ◽  
Re’em Sari
Keyword(s):  
Major Axis ◽  
Statistical Properties ◽  
Strong Interactions ◽  
Tidal Effects ◽  
Semi Major Axis ◽  
Tidal Disruption ◽  
Loss Cone ◽  
Tidal Interactions ◽  
Radius Of Influence ◽  
History Of

Abstract We study the correlations between the dynamical history of a star that eventually experience a tidal disruption events (TDE), and the properties of the TDE itself. As expected, we find that (i) in empty loss cone at the radius of influence, most TDEs are non-violent TDEs, i.e., the star’s periastron is only a bit smaller than the tidal radius. These stars had experienced strong tidal interactions with the SMBH, just slightly outside the tidal radius. (ii) in full loss cone at the radius of influence, most TDEs are violent, i.e., the star’s periastron is significantly smaller than the tidal radius. These stars did not previously encounter strong tidal effects. Nevertheless, we demonstrate that even in extremely empty or extremely full loss cone a finite fraction of order $\sim 10\%$ of the events are non-typical. This is due to two surprising effects: (i) In an empty LC, a logarithmic fraction of the events are associated with stars that entered the loss cone via strong scatterings. Those events are usually violent penetrating deep into the loss cone. (ii) In full loss cone, orbits with semi-major axis smaller than the radius of influence, where the loss cone is marginally empty, dominate the TDEs rate. As a result, constant fraction of TDEs involve stars in an empty loss cone orbits, which have typically experienced strong interactions with the SMBH in previous orbits.

scholarly journals HD 83443: a system with two Saturns

2004 ◽  
Vol 202 ◽  
pp. 84-86 ◽  
Author(s):  
M. Mayor ◽  
D. Naef ◽  
F. Pepe ◽  
D. Queloz ◽  
N. C. Santos ◽  
...  
Keyword(s):  
Planetary System ◽  
Major Axis ◽  
Giant Planets ◽  
Outer Planet ◽  
Semi Major Axis ◽  
Dynamical Study ◽  
Low Mass ◽  
The Stability ◽  
Extrasolar Planetary System

We report the discovery of an extrasolar planetary system with two Saturnian planets around the star HD 83443. The new planetary system is unusual by more than one aspect, as it contains two very low–mass gaseous giant planets, both on very tight orbits. Among the planets detected so far, the inner planet has the smallest semi–major axis (0.038 AU) and period (2.985 days) whereas the outer planet is the lightest one with m2 sin i = 0.53 MSat. A preliminary dynamical study confirms the stability of the system.

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