scholarly journals Giant Planets, Tiny Stars: Producing Short-period Planets around White Dwarfs with the Eccentric Kozai–Lidov Mechanism

2021 ◽  
Vol 922 (1) ◽  
pp. 4
Author(s):  
Alexander P. Stephan ◽  
Smadar Naoz ◽  
B. Scott Gaudi
Keyword(s):  
Direct Evidence ◽  
Giant Planet ◽  
Giant Planets ◽  
Tidal Effects ◽  
Stellar Envelope ◽  
Orbital Parameters ◽  
Short Period ◽  
Migration Mechanism ◽  
Red Giant ◽  
Host Stars

Abstract The recent discoveries of WD J091405.30+191412.25 (WD J0914 hereafter), a white dwarf (WD) likely accreting material from an ice-giant planet, and WD 1856+534 b (WD 1856 b hereafter), a Jupiter-sized planet transiting a WD, are the first direct evidence of giant planets orbiting WDs. However, for both systems, the observations indicate that the planets’ current orbital distances would have put them inside the stellar envelope during the red-giant phase, implying that the planets must have migrated to their current orbits after their host stars became WDs. Furthermore, WD J0914 is a very hot WD with a short cooling time that indicates a fast migration mechanism. Here, we demonstrate that the Eccentric Kozai–Lidov Mechanism, combined with stellar evolution and tidal effects, can naturally produce the observed orbital configurations, assuming that the WDs have distant stellar companions. Indeed, WD 1856 is part of a stellar triple system, being a distant companion to a stellar binary. We provide constraints for the orbital and physical characteristics for the potential stellar companion of WD J0914 and determine the initial orbital parameters of the WD 1856 system.

scholarly journals Constraining Planetary Migration Mechanisms in Systems of Giant Planets

2013 ◽  
Vol 8 (S299) ◽  
pp. 386-390
Author(s):  
Rebekah I. Dawson ◽  
Ruth A. Murray-Clay ◽  
John Asher Johnson
Keyword(s):  
Giant Planet ◽  
Giant Planets ◽  
Tidal Dissipation ◽  
Hot Jupiters ◽  
Short Period ◽  
Pile Up ◽  
Planetary Migration ◽  
Multi Body ◽  
Host Stars

AbstractIt was once widely believed that planets formed peacefully in situ in their proto-planetary disks and subsequently remain in place. Instead, growing evidence suggests that many giant planets undergo dynamical rearrangement that results in planets migrating inward in the disk, far from their birthplaces. However, it remains debated whether this migration is caused by smooth planet-disk interactions or violent multi-body interactions. Both classes of model can produce Jupiter-mass planets orbiting within 0.1 AU of their host stars, also known as hot Jupiters. In the latter class of model, another planet or star in the system perturbs the Jupiter onto a highly eccentric orbit, which tidal dissipation subsequently shrinks and circularizes during close passages to the star. We assess the prevalence of smooth vs. violent migration through two studies. First, motivated by the predictions of Socrates et al. (2012), we search for super-eccentric hot Jupiter progenitors by using the “photoeccentric effect” to measure the eccentricities of Kepler giant planet candidates from their transit light curves. We find a significant lack of super- eccentric proto-hot Jupiters compared to the number expected, allowing us to place an upper limit on the fraction of hot Jupiters created by stellar binaries. Second, if both planet-disk and multi-body interactions commonly cause giant planet migration, physical properties of the proto-planetary environment may determine which is triggered. We identify three trends in which giant planets orbiting metal rich stars show signatures of planet-planet interactions: (1) gas giants orbiting within 1 AU of metal-rich stars have a range of eccentricities, whereas those orbiting metal- poor stars are restricted to lower eccentricities; (2) metal-rich stars host most eccentric proto-hot Jupiters undergoing tidal circularization; and (3) the pile-up of short-period giant planets, missing in the Kepler sample, is a feature of metal-rich stars and is largely recovered for giants orbiting metal-rich Kepler host stars. These two studies suggest that both disk migration and planet-planet interactions may be widespread, with the latter occurring primarily in metal-rich planetary systems where multiple giant planets can form. Funded by NSF-GRFP DGE-1144152.

scholarly journals A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS

2019 ◽  
Vol 623 ◽  
pp. A100 ◽  
Author(s):  
L. D. Nielsen ◽  
F. Bouchy ◽  
O. Turner ◽  
H. Giles ◽  
A. Suárez Mascareño ◽  
...  
Keyword(s):  
Giant Planet ◽  
Eclipsing Binaries ◽  
Giant Planets ◽  
High Angular Resolution ◽  
Short Period ◽  
Resolution Imaging ◽  
And Migration ◽  
Host Stars ◽  
Jovian Planet ◽  
Rule Out

The Transiting Exoplanet Survey Satellite TESS has begun a new age of exoplanet discoveries around bright host stars. We present the discovery of HD 1397b (TOI-120.01), a giant planet in an 11.54-day eccentric orbit around a bright (V= 7.9) G-type subgiant. We estimate both host star and planetary parameters consistently usingEXOFASTv2based on TESS time-series photometry of transits and radial velocity measurements with CORALIE and MINERVA-Australis. We also present high angular resolution imaging with NaCo to rule out any nearby eclipsing binaries. We find that HD 1397b is a Jovian planet, with a mass of 0.415 ± 0.020MJand a radius of 1.026 ± 0.026RJ. Characterising giant planets in short-period eccentric orbits, such as HD 1397b, is important for understanding and testing theories for the formation and migration of giant planets as well as planet-star interactions.

scholarly journals Enhanced Lidov–Kozai migration and the formation of the transiting giant planet WD 1856+534 b

2020 ◽  
Vol 501 (1) ◽  
pp. 507-514 ◽  
Author(s):  
Christopher E O’Connor ◽  
Bin Liu ◽  
Dong Lai
Keyword(s):  
Main Sequence ◽  
Semimajor Axis ◽  
Giant Planet ◽  
Giant Planets ◽  
Occurrence Rate ◽  
M Dwarfs ◽  
High Eccentricity ◽  
Absolute Limit ◽  
Short Period ◽  
Wide Range

ABSTRACT We investigate the possible origin of the transiting giant planet WD 1856+534 b, the first strong exoplanet candidate orbiting a white dwarf, through high-eccentricity migration (HEM) driven by the Lidov–Kozai (LK) effect. The host system’s overall architecture is a hierarchical quadruple in the ‘2 + 2’ configuration, owing to the presence of a tertiary companion system of two M-dwarfs. We show that a secular inclination resonance in 2 + 2 systems can significantly broaden the LK window for extreme eccentricity excitation (e ≳ 0.999), allowing the giant planet to migrate for a wide range of initial orbital inclinations. Octupole effects can also contribute to the broadening of this ‘extreme’ LK window. By requiring that perturbations from the companion stars be able to overcome short-range forces and excite the planet’s eccentricity to e ≃ 1, we obtain an absolute limit of $a_{1} \gtrsim 8 \, \mathrm{au}\, (a_{3} / 1500 \, \mathrm{au})^{6/7}$ for the planet’s semimajor axis just before migration (where a3 is the semimajor axis of the ‘outer’ orbit). We suggest that, to achieve a wide LK window through the 2 + 2 resonance, WD 1856 b likely migrated from $30 \, \mathrm{au}\lesssim a_{1} \lesssim 60 \, \mathrm{au}$, corresponding to ∼10–$20 \, \mathrm{au}$ during the host’s main-sequence phase. We discuss possible difficulties of all flavours of HEM affecting the occurrence rate of short-period giant planets around white dwarfs.

scholarly journals The discovery of WASP-151b, WASP-153b, WASP-156b: Insights on giant planet migration and the upper boundary of the Neptunian desert

2018 ◽  
Vol 610 ◽  
pp. A63 ◽  
Author(s):  
O. D. S. Demangeon ◽  
F. Faedi ◽  
G. Hébrard ◽  
D. J. A. Brown ◽  
S. C. C. Barros ◽  
...  
Keyword(s):  
Giant Planet ◽  
Ultra Violet ◽  
Equilibrium Temperature ◽  
Good Precision ◽  
High Eccentricity ◽  
Short Period ◽  
Orbital Periods ◽  
Host Stars ◽  
Better Than ◽  
Upper Boundary

To investigate the origin of the features discovered in the exoplanet population, the knowledge of exoplanets' mass and radius with a good precision (≲10%) is essential. To achieve this purpose the discovery of transiting exoplanets around bright stars is of prime interest. In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15%. WASP-151b and WASP-153b are two hot Saturns with masses, radii, densities and equilibrium temperatures of 0.31−0.03+0.04 MJ, 1.13−0.03+0.03 RJ, 0.22−0.02+0.03 ρJ and 1290−10+20 K, and 0.39−0.02+0.02 MJ, 1.55−0.08+0.10 RJ, 0.11−0.02+0.02 ρJ and 1700−0.40+0.40 K, respectively. Their host stars are early G type stars (with mag V ~ 13) and their orbital periods are 4.53 and 3.33 days, respectively. WASP-156b is a super-Neptune orbiting a K type star (mag V = 11.6). It has a mass of 0.128−0.009+0.010 MJ, a radius of 0.51−0.02+0.02 RJ, a density of 1.0−0.1+0.1 ρJ, an equilibrium temperature of 970−20+30 K and an orbital period of 3.83 days. The radius of WASP-151b appears to be only slightly inflated, while WASP-153b presents a significant radius anomaly compared to a recently published model. WASP-156b, being one of the few well characterized super-Neptunes, will help to constrain the still debated formation of Neptune size planets and the transition between gas and ice giants. The estimates of the age of these three stars confirms an already observed tendency for some stars to have gyrochronological ages significantly lower than their isochronal ages. We propose that high eccentricity migration could partially explain this behavior for stars hosting a short period planet. Finally, these three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert. Their characteristics support that the ultra-violet irradiation plays an important role in this depletion of planets observed in the exoplanet population.

scholarly journals Composition of massive giant planets

2010 ◽  
Vol 6 (S276) ◽  
pp. 95-100
Author(s):  
Ravit Helled ◽  
Peter Bodenheimer ◽  
Jack J. Lissauer
Keyword(s):  
Large Range ◽  
Giant Planet ◽  
Giant Planets ◽  
Heavy Elements ◽  
Formation Model ◽  
The Core ◽  
Accretion Model ◽  
Low Mass ◽  
Core Accretion ◽  
Host Stars

AbstractThe two current models for giant planet formation are core accretion and disk instability. We discuss the core masses and overall planetary enrichment in heavy elements predicted by the two formation models, and show that both models could lead to a large range of final compositions. For example, both can form giant planets with nearly stellar compositions. However, low-mass giant planets, enriched in heavy elements compared to their host stars, are more easily explained by the core accretion model. The final structure of the planets, i.e., the distribution of heavy elements, is not firmly constrained in either formation model.

scholarly journals Orbital decay of short-period gas giants under evolving tides

2019 ◽  
Vol 486 (3) ◽  
pp. 3963-3974 ◽  
Author(s):  
Jaime A Alvarado-Montes ◽  
Carolina García-Carmona
Keyword(s):  
Extreme Case ◽  
Orbital Evolution ◽  
Giant Planets ◽  
Tidal Interactions ◽  
Extrasolar Systems ◽  
Orbital Decay ◽  
Short Period ◽  
Order Of Magnitude ◽  
Formation And Evolution ◽  
Host Stars

Abstract The discovery of many giant planets in close-in orbits and the effect of planetary and stellar tides in their subsequent orbital decay have been extensively studied in the context of planetary formation and evolution theories. Planets orbiting close to their host stars undergo close encounters, atmospheric photoevaporation, orbital evolution, and tidal interactions. In many of these theoretical studies, it is assumed that the interior properties of gas giants remain static during orbital evolution. Here, we present a model that allows for changes in the planetary radius as well as variations in the planetary and stellar dissipation parameters, caused by the planet’s contraction and change of rotational rates from the strong tidal fields. In this semi-analytical model, giant planets experience a much slower tidal-induced circularization compared to models that do not consider these instantaneous changes. We predict that the eccentricity damping time-scale increases about an order of magnitude in the most extreme case for too inflated planets, large eccentricities, and when the planet’s tidal properties are calculated according to its interior structural composition. This finding potentially has significant implications on interpreting the period–eccentricity distribution of known giant planets as it may naturally explain the large number of non-circularized, close period currently known. Additionally, this work may help to constrain some models of planetary interiors, and contribute to a better insight about how tides affect the orbital evolution of extrasolar systems.

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 Orbit circularization time in binary stellar systems

1984 ◽  
Vol 105 ◽  
pp. 411-414 ◽  
Author(s):  
M. Mayor ◽  
J.-C. Mermilliod
Keyword(s):  
Time Scale ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Spectroscopic Binaries ◽  
Stellar Systems ◽  
Orbital Parameters ◽  
Short Period ◽  
Red Giant

We have analyzed the orbital parameters of 33 red dwarf and 17 red giant spectroscopic binaries belonging to open clusters to deduce the time-scale for orbital circularization. The dynamical evolution of BD +23°635, a short period binary member of the Hyades, should result in the formation either of a cataclysmic binary or a WUMa system.

scholarly journals Formation of hot Jupiters through secular chaos and dynamical tides

2019 ◽  
Vol 486 (2) ◽  
pp. 2265-2280 ◽  
Author(s):  
Jean Teyssandier ◽  
Dong Lai ◽  
Michelle Vick
Keyword(s):  
Semimajor Axis ◽  
Giant Planet ◽  
Giant Planets ◽  
Orbital Energy ◽  
High Eccentricity ◽  
Hot Jupiters ◽  
Orbital Decay ◽  
Short Period ◽  
Orbital Periods ◽  
Hot Jupiter

Abstract The population of giant planets on short-period orbits can potentially be explained by some flavours of high-eccentricity migration. In this paper, we investigate one such mechanism involving ‘secular chaos’, in which secular interactions between at least three giant planets push the inner planet to a highly eccentric orbit, followed by tidal circularization and orbital decay. In addition to the equilibrium tidal friction, we incorporate dissipation due to dynamical tides that are excited inside the giant planet. Using the method of Gaussian rings to account for planet–planet interactions, we explore the conditions for extreme eccentricity excitation via secular chaos and the properties of hot Jupiters formed in this migration channel. Our calculations show that once the inner planet reaches a sufficiently large eccentricity, dynamical tides quickly dissipate the orbital energy, producing an eccentric warm Jupiter, which then decays in semimajor axis through equilibrium tides to become a hot Jupiter. Dynamical tides help the planet avoid tidal disruption, increasing the chance of forming a hot Jupiter, although not all planets survive the process. We find that the final orbital periods generally lie in the range of 2–3 d, somewhat shorter than those of the observed hot Jupiter population. We couple the planet migration to the stellar spin evolution to predict the final spin-orbit misalignments. The distribution of the misalignment angles we obtain shows a lack of retrograde orbits compared to observations. Our results suggest that high-eccentricity migration via secular chaos can only account for a fraction of the observed hot Jupiter population.

scholarly journals Exploring the realm of scaled solar system analogues with HARPS

2018 ◽  
Vol 615 ◽  
pp. A175 ◽  
Author(s):  
D. Barbato ◽  
A. Sozzetti ◽  
S. Desidera ◽  
M. Damasso ◽  
A. S. Bonomo ◽  
...  
Keyword(s):  
Solar System ◽  
High Precision ◽  
Giant Planet ◽  
Planetary Systems ◽  
Giant Planets ◽  
Orbital Parameters ◽  
Long Period ◽  
Link Type ◽  
Low Mass ◽  
High Cadence

Context. The assessment of the frequency of planetary systems reproducing the solar system’s architecture is still an open problem in exoplanetary science. Detailed study of multiplicity and architecture is generally hampered by limitations in quality, temporal extension and observing strategy, causing difficulties in detecting low-mass inner planets in the presence of outer giant planets. Aims. We present the results of high-cadence and high-precision HARPS observations on 20 solar-type stars known to host a single long-period giant planet in order to search for additional inner companions and estimate the occurence rate fp of scaled solar system analogues – in other words, systems featuring lower-mass inner planets in the presence of long-period giant planets. Methods. We carried out combined fits of our HARPS data with literature radial velocities using differential evolution MCMC to refine the literature orbital solutions and search for additional inner planets. We then derived the survey detection limits to provide preliminary estimates of fp. Results. We generally find better constrained orbital parameters for the known planets than those found in the literature; significant updates can be especially appreciated on half of the selected planetary systems. While no additional inner planet is detected, we find evidence for previously unreported long-period massive companions in systems HD 50499 and HD 73267. We finally estimate the frequency of inner low mass (10–30 M⊕) planets in the presence of outer giant planets as fp < 9.84% for P < 150 days. Conclusions. Our preliminary estimate of fp is significantly lower than the literature values for similarly defined mass and period ranges; the lack of inner candidate planets found in our sample can also be seen as evidence corroborating the inwards-migration formation model for super-Earths and mini-Neptunes. Our results also underline the need for high-cadence and high-precision followup observations as the key to precisely determine the occurence of solar system analogues.

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