scholarly journals Resonance in the K2-19 system is at odds with its high reported eccentricities

2020 ◽  
Vol 496 (3) ◽  
pp. 3101-3111
Author(s):  
Antoine C Petit ◽  
Erik A Petigura ◽  
Melvyn B Davies ◽  
Anders Johansen
Keyword(s):  
Planet Formation ◽  
Planetary System ◽  
Recent Analysis ◽  
Circular Orbits ◽  
Tidal Dissipation ◽  
Outer Planets ◽  
Mean Motion ◽  
Orbital Configuration ◽  
Orbital Solution ◽  
Rule Out

ABSTRACT K2-19 hosts a planetary system composed of two outer planets, b and c, with size of 7.0 ± 0.2 R⊕ and 4.1 ± 0.2 R⊕, and an inner planet, d, with a radius of 1.11 ± 0.05 R⊕. A recent analysis of Transit-Timing Variations (TTVs) suggested b and c are close to but not in 3:2 mean motion resonance (MMR) because the classical resonant angles circulate. Such an architecture challenges our understanding of planet formation. Indeed, planet migration through the protoplanetary disc should lead to a capture into the MMR. Here, we show that the planets are in fact, locked into the 3:2 resonance despite circulation of the conventional resonant angles and aligned periapses. However, we show that such an orbital configuration cannot be maintained for more than a few hundred million years due to the tidal dissipation experienced by planet d. The tidal dissipation remains efficient because of a secular forcing of the innermost planet eccentricity by planets b and c. While the observations strongly rule out an orbital solution where the three planets are on close to circular orbits, it remains possible that a fourth planet is affecting the TTVs such that the four planet system is consistent with the tidal constraints.

scholarly journals The HADES RV Programme with HARPS-N at TNG

2018 ◽  
Vol 617 ◽  
pp. A104 ◽  
Author(s):  
M. Pinamonti ◽  
M. Damasso ◽  
F. Marzari ◽  
A. Sozzetti ◽  
S. Desidera ◽  
...  
Keyword(s):  
Planetary System ◽  
Orbital Evolution ◽  
Dynamical Analysis ◽  
Outer Planet ◽  
Orbital Configuration ◽  
Orbital Instability ◽  
Astrometric Data ◽  
Long Term Trend ◽  
Orbital Solution

We present 20 yr of radial velocity (RV) measurements of the M1 dwarf Gl15A, combining five years of intensive RV monitoring with the HARPS-N spectrograph with 15 yr of archival HIRES/Keck RV data. We have carried out an MCMC-based analysis of the RV time series, inclusive of Gaussian Process (GP) approach to the description of stellar activity induced RV variations. Our analysis confirms the Keplerian nature and refines the orbital solution for the 11.44-day period super Earth, Gl15A b, reducing its amplitude to 1.68−0.18+0.17 m s−1 (M sin i = 3.03−0.44+0.46 M⊕), and successfully models a long-term trend in the combined RV dataset in terms of a Keplerian orbit with a period around 7600 days and an amplitude of 2.5−1.0+1.3 m s−1, corresponding to a super-Neptune mass (M sin i = 36−18+25 M⊕) planetary companion. We also discuss the present orbital configuration of Gl15A planetary system in terms of the possible outcomes of Lidov–Kozai interactions with the wide-separation companion Gl15B in a suite of detailed numerical simulations. In order to improve the results of the dynamical analysis, we have derived a new orbital solution for the binary system, combining our RV measurements with astrometric data from the WDS catalogue. The eccentric Lidov–Kozai analysis shows the strong influence of Gl15B on the Gl15A planetary system, which can produce orbits compatible with the observed configuration for initial inclinations of the planetary system between 75° and 90°, and can also enhance the eccentricity of the outer planet well above the observed value, even resulting in orbital instability, for inclinations around 0° and 15°−30°. The Gl15A system is the multi-planet system closest to Earth, at 3.56 pc, and hosts the longest period RV sub-Jovian mass planet discovered so far. Its orbital architecture constitutes a very important laboratory for the investigation of formation and orbital evolution scenarios for planetary systems in binary stellar systems.

scholarly journals An unusually low density ultra-short period super-Earth and three mini-Neptunes around the old star TOI-561

2020 ◽  
Author(s):  
G Lacedelli ◽  
L Malavolta ◽  
L Borsato ◽  
G Piotto ◽  
D Nardiello ◽  
...  
Keyword(s):  
Transit Time ◽  
Time Variation ◽  
Planetary System ◽  
Radial Velocities ◽  
Low Density ◽  
Outer Planets ◽  
Short Period ◽  
The Stability

Abstract Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterisation of the planetary system orbiting the late G dwarf After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra-short period (USP) super-Earth (TOI-561 b) with period Pb = 0.45 d, mass Mb = 1.59 ± 0.36 M⊕ and radius Rb = 1.42 ± 0.07 R⊕, and three mini-Neptunes: TOI-561 c, with Pc = 10.78 d, Mc = 5.40 ± 0.98 M⊕, Rc = 2.88 ± 0.09 R⊕; TOI-561 d, with Pd = 25.6 d, Md = 11.9 ± 1.3 M⊕, Rd = 2.53 ± 0.13 R⊕; and TOI-561 e, with Pe = 77.2 d, Me = 16.0 ± 2.3 M⊕, Re = 2.67 ± 0.11 R⊕. Having a density of 3.0 ± 0.8 g cm−3, TOI-561 b is the lowest density USP planet known to date. Our N-body simulations confirm the stability of the system and predict a strong, anti-correlated, long-term transit time variation signal between planets d and e. The unusual density of the inner super-Earth and the dynamical interactions between the outer planets make TOI-561 an interesting follow-up target.

β Pictoris and other star spectra, in connection with planet formation

2004 ◽  
Vol 202 ◽  
pp. 300-307
Author(s):  
Anne. M. Lagrange ◽  
Herve Beust
Keyword(s):  
Planet Formation ◽  
Planetary System ◽  
Present Knowledge ◽  
Debris Disks ◽  
System Activity ◽  
Pms Stars

We review here the present knowledge on the gaseous phases of debris disks found around MS and old PMS stars, and make an attempt to connect them with planetary system activity.

scholarly journals Orbital evolution of Saturn’s satellites due to the interaction between the moons and the massive rings

2020 ◽  
Vol 640 ◽  
pp. L15
Author(s):  
Ayano Nakajima ◽  
Shigeru Ida ◽  
Yota Ishigaki
Keyword(s):  
Orbital Evolution ◽  
The Self ◽  
Mean Motion Resonances ◽  
First Order ◽  
Mean Motion ◽  
Saturn’S Satellites ◽  
Orbital Configuration ◽  
Self Gravity ◽  
Spiral Arm ◽  
Orbital Migration

Context. Saturn’s mid-sized moons (satellites) have a puzzling orbital configuration with trapping in mean-motion resonances with every-other pairs (Mimas-Tethys 4:2 and Enceladus-Dione 2:1). To reproduce their current orbital configuration on the basis of a recent model of satellite formation from a hypothetical ancient massive ring, adjacent pairs must pass first-order mean-motion resonances without being trapped. Aims. The trapping could be avoided by fast orbital migration and/or excitation of the satellite’s eccentricity caused by gravitational interactions between the satellites and the rings (the disk), which are still unknown. In our research we investigate the satellite orbital evolution due to interactions with the disk through full N-body simulations. Methods. We performed global high-resolution N-body simulations of a self-gravitating particle disk interacting with a single satellite. We used N ∼ 105 particles for the disk. Gravitational forces of all the particles and their inelastic collisions are taken into account. Results. Dense short-wavelength wake structure is created by the disk self-gravity and a few global spiral arms are induced by the satellite. The self-gravity wakes regulate the orbital evolution of the satellite, which has been considered as a disk spreading mechanism, but not as a driver for the orbital evolution. Conclusions. The self-gravity wake torque to the satellite is so effective that the satellite migration is much faster than was predicted with the spiral arm torque. It provides a possible model to avoid the resonance capture of adjacent satellite pairs and establish the current orbital configuration of Saturn’s mid-sized satellites.

scholarly journals Multiple mean motion resonances in the HR 8799 planetary system

2014 ◽  
Vol 440 (4) ◽  
pp. 3140-3171 ◽  
Author(s):  
Krzysztof Goździewski ◽  
Cezary Migaszewski
Keyword(s):  
Planetary System ◽  
Mean Motion Resonances ◽  
Mean Motion

scholarly journals Two new free-floating or wide-orbit planets from microlensing

2019 ◽  
Vol 622 ◽  
pp. A201 ◽  
Author(s):  
Przemek Mróz ◽  
Andrzej Udalski ◽  
David P. Bennett ◽  
Yoon-Hyun Ryu ◽  
Takahiro Sumi ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Milky Way ◽  
Planet Formation ◽  
Physical Mechanism ◽  
Galactic Disk ◽  
Galactic Bulge ◽  
Brown Dwarf ◽  
Low Mass ◽  
Rule Out

Planet formation theories predict the existence of free-floating planets that have been ejected from their parent systems. Although they emit little or no light, they can be detected during gravitational microlensing events. Microlensing events caused by rogue planets are characterized by very short timescales tE (typically below two days) and small angular Einstein radii θE (up to several μas). Here we present the discovery and characterization of two ultra-short microlensing events identified in data from the Optical Gravitational Lensing Experiment (OGLE) survey, which may have been caused by free-floating or wide-orbit planets. OGLE-2012-BLG-1323 is one of the shortest events discovered thus far (tE = 0.155 ± 0.005 d, θE = 2.37 ± 0.10μas) and was caused by an Earth-mass object in the Galactic disk or a Neptune-mass planet in the Galactic bulge. OGLE-2017-BLG-0560 (tE = 0.905 ± 0.005 d, θE = 38.7 ± 1.6μas) was caused by a Jupiter-mass planet in the Galactic disk or a brown dwarf in the bulge. We rule out stellar companions up to a distance of 6.0 and 3.9 au, respectively. We suggest that the lensing objects, whether located on very wide orbits or free-floating, may originate from the same physical mechanism. Although the sample of ultrashort microlensing events is small, these detections are consistent with low-mass wide-orbit or unbound planets being more common than stars in the Milky Way.

scholarly journals Gravitational Radiation by Ultrarelativistic Bodies

1974 ◽  
Vol 64 ◽  
pp. 60-60
Author(s):  
Peter Jocelyn Westervelt
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Direct Observation ◽  
Gravitational Radiation ◽  
Indirect Evidence ◽  
Forward Direction ◽  
Recent Analysis ◽  
Circular Orbits ◽  
Low Efficiency

I have shown (Westervelt, 1966) that ultrarelativistic bodies do not radiate gravitational waves in the forward direction. This work has been extended so as to apply to circular orbits. Even if low efficiency of generation precludes direct observation of gravitational waves, indirect evidence for their existence is available in a recent analysis (Westervelt, 1969) of Shapiro's fourth test of general relativity.

scholarly journals Stability Mechanism of Planetary System of ν Andromedae

2004 ◽  
Vol 202 ◽  
pp. 202-204 ◽  
Author(s):  
Hiroshi Kinoshita ◽  
Hiroshi Nakai
Keyword(s):  
Perturbation Theory ◽  
Planetary System ◽  
Secular Resonance ◽  
Secular Perturbation ◽  
Outer Planets ◽  
The Stability

Three planets are detected around ν Andromedae. The stability of Upsilon Andromedae Planetary system is maintained by the co rotation of the pericenters of the two outer planets. If the pericenters of the two outer planets move independently, the planetary system becomes unstable. The corotation of the pericenters is explained by the secular perturbation theory. This corotation is not a secular resonance.

scholarly journals Companion-driven evolution of massive stellar binaries

2019 ◽  
Vol 488 (2) ◽  
pp. 2480-2492 ◽  
Author(s):  
Sanaea C Rose ◽  
Smadar Naoz ◽  
Aaron M Geller
Keyword(s):  
Dynamical Evolution ◽  
Dynamical Process ◽  
Tidal Dissipation ◽  
Triple Systems ◽  
Secular Evolution ◽  
Gravitational Perturbations ◽  
Orbital Configuration ◽  
General Relativistic ◽  
X Ray Binaries ◽  
Insight Into

ABSTRACT At least $70\, {\rm per\, cent}$ of massive OBA-type stars reside in binary or higher order systems. The dynamical evolution of these systems can lend insight into the origins of extreme phenomena such as X-ray binaries and gravitational wave sources. In one such dynamical process, the Eccentric Kozai–Lidov (EKL) mechanism, a third companion star alters the secular evolution of a binary system. For dynamical stability, these triple systems must have a hierarchical configuration. We explore the effects of a distant third companion’s gravitational perturbations on a massive binary’s orbital configuration before significant stellar evolution has taken place (≤10 Myr). We include tidal dissipation and general relativistic precession. With large (38 000 total) Monte Carlo realizations of massive hierarchical triples, we characterize imprints of the birth conditions on the final orbital distributions. Specifically, we find that the final eccentricity distribution over the range of 0.1–0.7 is an excellent indicator of its birth distribution. Furthermore, we find that the period distributions have a similar mapping for wide orbits. Finally, we demonstrate that the observed period distribution for approximately 10-Myr-old massive stars is consistent with EKL evolution.

scholarly journals Six transiting planets and a chain of Laplace resonances in TOI-178

2021 ◽  
Author(s):  
Adrien Leleu
Keyword(s):  
Planet Formation ◽  
Planetary Systems ◽  
Single System ◽  
Transiting Planets ◽  
Orbital Configuration ◽  
Resonant Systems ◽  
Formation And Evolution ◽  
A Chain ◽  
Formation Phase

<p class="p1">Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. As unveiled by TESS, CHEOPS, ESPRESSO, NGTS and SPECULOOS, TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, all planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet. TOI-178 have hence several characteristics that were not previously observed in a single system, making it a key system for the study of processes of formation and evolution of planetary systems. We will review what we know of TOI-178, and what we expect from futur observations.</p>

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