scholarly journals Tidal evolution of exoplanetary systems hosting potentially habitable exoplanets. The cases of LHS-1140 b-c and K2-18 b-c

2020 ◽  
Vol 494 (4) ◽  
pp. 5082-5090
Author(s):  
G O Gomes ◽  
S Ferraz-Mello
Keyword(s):  
Orbital Plane ◽  
Viscosity Coefficient ◽  
Orbital Evolution ◽  
Rotation Axes ◽  
Exoplanetary Systems ◽  
Tidal Theory ◽  
Orbit Evolution ◽  
Earth Like Planets ◽  
Low Mass ◽  
Three Body

ABSTRACT We present a model to study secularly and tidally evolving three-body systems composed by two low-mass planets orbiting a star, in the case where the bodies rotation axes are always perpendicular to the orbital plane. The tidal theory allows us to study the spin and orbit evolution of both stiff Earth-like planets and predominantly gaseous Neptune-like planets. The model is applied to study two recently discovered exoplanetary systems containing potentially habitable exoplanets (PHE): LHS-1140 b-c and K2-18 b-c. For the former system, we show that both LHS-1140 b and c must be in nearly circular orbits. For K2-18 b-c, the combined analysis of orbital evolution time-scales with the current eccentricity estimation of K2-18 b allows us to conclude that the inner planet (K2-18 c) must be a Neptune-like gaseous body. Only this would allow for the eccentricity of K2-18 b to be in the range of values estimated in recent works (e = 0.20 ± 0.08), provided that the uniform viscosity coefficient of K2-18 b is greater than 2.4 × 1019 Pa s (which is a value characteristic of stiff bodies) and supposing that such system has an age of some Gyr.

scholarly journals The GAPS programme with HARPS-N at TNG

2018 ◽  
Vol 613 ◽  
pp. A41 ◽  
Author(s):  
L. Mancini ◽  
M. Esposito ◽  
E. Covino ◽  
J. Southworth ◽  
K. Biazzo ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Rotation Period ◽  
Orbital Plane ◽  
Orbital Evolution ◽  
Photometric Data ◽  
Light Curves ◽  
Physical Parameters ◽  
Synthesis Methods ◽  
Rotation Periods ◽  
Exoplanetary Systems

Context. The measurement of the orbital obliquity of hot Jupiters with different physical characteristics can provide clues to the mechanisms of migration and orbital evolution of this particular class of giant exoplanets. Aims. We aim to derive the degree of alignment between planetary orbit and stellar spin angular momentum vectors and look for possible links with other orbital and fundamental physical parameters of the star-planet system. We focus on the characterisation of five transiting planetary systems (HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60) and the determination of their sky-projected planet orbital obliquity through the measurement of the Rossiter–McLaughlin effect. Methods. We used HARPS-N high-precision radial velocity measurements, gathered during transit events, to measure the Rossiter–McLaughlin effect in the target systems and determine the sky-projected angle between the planetary orbital plane and stellar equator. The characterisation of stellar atmospheric parameters was performed by exploiting the HARPS-N spectra, using line equivalent width ratios and spectral synthesis methods. Photometric parameters of the five transiting exoplanets were re-analysed through 17 new light curves, obtained with an array of medium-class telescopes, and other light curves from the literature. Survey-time-series photometric data were analysed for determining the rotation periods of the five stars and their spin inclination. Results. From the analysis of the Rossiter–McLaughlin effect we derived a sky-projected obliquity of λ = 21.2° ± 8.7°, λ = −54°−13°+41°, λ = −2.1° ± 3.0°, λ = 0° ± 11°, and λ = −129° ± 17° for HAT-P-3 b, HAT-P-12 b, HAT-P-22 b, WASP-39 b, and WASP-60 b, respectively. The latter value indicates that WASP-60 b is moving on a retrograde orbit. These values represent the first measurements of λ for the five exoplanetary systems under study. The stellar activity of HAT-P-22 indicates a rotation period of 28.7 ± 0.4 days, which allowed us to estimate the true misalignment angle of HAT-P-22 b, ψ = 24° ± 18°. The revision of the physical parameters of the five exoplanetary systems returned values that are fully compatible with those existing in the literature. The exception to this is the WASP-60 system, for which, based on higher quality spectroscopic and photometric data, we found a more massive and younger star and a larger and hotter planet.

scholarly journals Tidal dissipation in rotating low-mass stars and implications for the orbital evolution of close-in planets

2017 ◽  
Vol 604 ◽  
pp. A112 ◽  
Author(s):  
F. Gallet ◽  
E. Bolmont ◽  
S. Mathis ◽  
C. Charbonnel ◽  
L. Amard
Keyword(s):  
Orbital Evolution ◽  
Low Mass Stars ◽  
Tidal Dissipation ◽  
Low Mass

Dust discs around low-mass main-sequence stars

1988 ◽  
Vol 325 (1587) ◽  
pp. 423-437 ◽  
Keyword(s):  
Thermal Emission ◽  
Orbital Evolution ◽  
Prima Facie ◽  
Mass Star ◽  
Orbital Inclination ◽  
Sources And Sinks ◽  
Central Regions ◽  
Low Mass ◽  
The Difference ◽  
Two Sides

Current understanding of the formation of circumstellar discs as a natural accompaniment to the process of low-mass star formation is briefly reviewed. Models of the thermal emission from the dust discs around the prototype stars a Lyr, a PsA, P Pic and 8 Eri are discussed, which indicate that the central regions of three of these discs are almost devoid of dust within radii ranging between 17 and 26 AU, with the temperature of the hottest dust lying between about 115 and 210 K. One possible explanation of the dust-free zones is the presence of a planet at the inner boundary of each cloud that sweeps up grains crossing its orbit. The discs have outer radii that range between about 250 and 800 AU and have dust masses that are unlikely to exceed about 300 Earth masses. Assuming a gas: dust ratio of 100:1 for the pre-mainsequence disc this corresponds to a mass of ca. 0.1 M Q comparable to that of the premain-sequence star HL Tau. The colour, diameter and thickness of the optical image of P Pic, obtained by coronagraphic techniques, have provided further information on the size, radial distribution of number density and orbital inclination of the grains. The difference in surface brightness on the two sides of the disc is puzzling, but might be explained if the grains are elongated and aligned by the combined effects of a stellar wind and a magnetic field of spiral configuration. Finally, we discuss the orbital evolution and lifetimes of particles in these discs, which are governed primarily by radiation pressure, Poynting-Robertson drag and grain-grain collisions. Although replenishment of these discs may be occurring, for example by grains ejected from comets, discs of initial radius ca. 1000 AU can survive Poynting-Robertson depletion over the stellar age and there is no prima facie evidence as yet in favour of a balance between sources and sinks of dust.

scholarly journals The diverse origin of exoplanets' eccentricities & inclinations

2010 ◽  
Vol 6 (S276) ◽  
pp. 221-224
Author(s):  
Eric B. Ford
Keyword(s):  
Rotation Axis ◽  
Orbital Evolution ◽  
Giant Planets ◽  
Direct Imaging ◽  
Wide Binary ◽  
Hot Jupiters ◽  
Short Period ◽  
New Type ◽  
Low Mass ◽  
Diverse Origin

AbstractRadial velocity surveys have discovered over 400 exoplanets. While measuring eccentricities of low-mass planets remains a challenge, giant exoplanets display a broad range of orbital eccentricities. Recently, spectroscopic measurements during transit have demonstrated that the short-period giant planets (“hot-Jupiters”) also display a broad range of orbital inclinations (relative to the rotation axis of the host star). Both properties pose a challenge for simple disk migration models and suggest that late-stage orbital evolution can play an important role in determining the final architecture of planetary systems. One possible formation mechanism for the inclined hot-Jupiters is some form of eccentricity excitation (e.g., planet scattering, secular perturbations due to a distant planet or wide binary) followed tidal circularization. The planet scattering hypothesis also makes predictions for the population of planets at large separations. Recent discoveries of planets on wide orbits via direct imaging and highly anticipated results from upcoming direct imaging campaigns are poised to provide a new type of constraint on planet formation. This proceedings describes recent progress in understanding the formation of giant exoplanets.

scholarly journals VLT/SPHERE astrometric confirmation and orbital analysis of the brown dwarf companion HR 2562 B

2018 ◽  
Vol 615 ◽  
pp. A177 ◽  
Author(s):  
A.-L. Maire ◽  
L. Rodet ◽  
C. Lazzoni ◽  
A. Boccaletti ◽  
W. Brandner ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Orbital Plane ◽  
Real Data ◽  
Far Infrared ◽  
Brown Dwarf ◽  
Orbital Parameters ◽  
System A ◽  
Low Mass ◽  
Debris Disk ◽  
Orbital Periods

Context. A low-mass brown dwarf has recently been imaged around HR 2562 (HD 50571), a star hosting a debris disk resolved in the far infrared. Interestingly, the companion location is compatible with an orbit coplanar with the disk and interior to the debris belt. This feature makes the system a valuable laboratory to analyze the formation of substellar companions in a circumstellar disk and potential disk-companion dynamical interactions. Aims. We aim to further characterize the orbital motion of HR 2562 B and its interactions with the host star debris disk. Methods. We performed a monitoring of the system over ~10 months in 2016 and 2017 with the VLT/SPHERE exoplanet imager. Results. We confirm that the companion is comoving with the star and detect for the first time an orbital motion at high significance, with a current orbital motion projected in the plane of the sky of 25 mas (~0.85 au) per year. No orbital curvature is seen in the measurements. An orbital fit of the SPHERE and literature astrometry of the companion without priors on the orbital plane clearly indicates that its orbit is (quasi-)coplanar with the disk. To further constrain the other orbital parameters, we used empirical laws for a companion chaotic zone validated by N-body simulations to test the orbital solutions that are compatible with the estimated disk cavity size. Non-zero eccentricities (>0.15) are allowed for orbital periods shorter than 100 yr, while only moderate eccentricities up to ~0.3 for orbital periods longer than 200 yr are compatible with the disk observations. A comparison of synthetic Herschel images to the real data does not allow us to constrain the upper eccentricity of the companion.

Orbits of Trojan Asteroids

1974 ◽  
Vol 62 ◽  
pp. 63-69 ◽  
Author(s):  
G. A. Chebotarev ◽  
N. A. Belyaev ◽  
R. P. Eremenko
Keyword(s):  
Solar System ◽  
Body Problem ◽  
Equations Of Motion ◽  
Orbital Evolution ◽  
Restricted Three Body Problem ◽  
Three Body Problem ◽  
Trojan Asteroids ◽  
Actual Motion ◽  
Three Body

In this paper the orbital evolution of Trojan asteroids are studied by integrating numerically the equations of motion over the interval 1660–2060, perturbations from Venus to Pluto being taken into account. The comparison of the actual motion of Trojans in the solar system with the theory based on the restricted three-body problem are given.

The impact of magnetism on tidal dynamics in the convective envelope of low-mass stars

2019 ◽  
Vol 15 (S354) ◽  
pp. 195-199
Author(s):  
A. Astoul ◽  
S. Mathis ◽  
C. Baruteau ◽  
F. Gallet ◽  
A. Strugarek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Orbital Evolution ◽  
Magnetic Contribution ◽  
Low Mass Stars ◽  
Convective Envelope ◽  
Tidal Waves ◽  
Tidal Interactions ◽  
Rotational Evolution ◽  
Low Mass ◽  
The Impact

AbstractFor the shortest period exoplanets, star-planet tidal interactions are likely to have played a major role in the ultimate orbital evolution of the planets and on the spin evolution of the host stars. Although low-mass stars are magnetically active objects, the question of how the star’s magnetic field impacts the excitation, propagation and dissipation of tidal waves remains open. We have derived the magnetic contribution to the tidal interaction and estimated its amplitude throughout the structural and rotational evolution of low-mass stars (from K to F-type). We find that the star’s magnetic field has little influence on the excitation of tidal waves in nearly circular and coplanar Hot-Jupiter systems, but that it has a major impact on the way waves are dissipated.

scholarly journals A low-mass stellar companion to the young variable star RZ Psc

2020 ◽  
Vol 496 (1) ◽  
pp. L75-L79
Author(s):  
Grant M Kennedy ◽  
Christian Ginski ◽  
Matthew A Kenworthy ◽  
Myriam Benisty ◽  
Thomas Henning ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Variable Star ◽  
Orbital Motion ◽  
Orbital Plane ◽  
Position Angle ◽  
Circumstellar Dust ◽  
Primary Star ◽  
Infrared Excess ◽  
Low Mass ◽  
Rz Psc

ABSTRACT RZ Psc is a young Sun-like star with a bright and warm infrared excess that is occasionally dimmed significantly by circumstellar dust structures. Optical depth arguments suggest that the dimming events do not probe a typical sightline through the circumstellar dust, and are instead caused by structures that appear above an optically thick mid-plane. This system may therefore be similar to systems where an outer disc is shadowed by material closer to the star. Here, we report the discovery that RZ Psc hosts a $0.12\, \mathrm{ M}_\odot$ companion at a projected separation of 23 au. We conclude that the disc must orbit the primary star. While we do not detect orbital motion, comparison of the angle of linear polarization of the primary with the companion’s on-sky position angle provides circumstantial evidence that the companion and disc may not share the same orbital plane. Whether the companion severely disrupts the disc, truncates it, or has little effect at all will require further observations of both the companion and disc.

scholarly journals Do three-body encounters in galactic nuclei affect compact binary merger rates?

2019 ◽  
Vol 14 (S351) ◽  
pp. 174-177 ◽  
Author(s):  
Alessandro A. Trani
Keyword(s):  
Galactic Nuclei ◽  
Orbital Plane ◽  
High Density ◽  
Dynamical Friction ◽  
Compact Binaries ◽  
Close Encounters ◽  
Compact Binary ◽  
Binary Black Hole ◽  
Merger Rate ◽  
Three Body

AbstractHigh-density cusps of compact remnants are expected to form around supermassive black holes (SMBHs) in galactic nuclei via dynamical friction and two-body relaxation. Due to the high density, binaries in orbit around the SMBH can frequently undergo close encounters with compact remnants from the cusp. This can affect the gravitational wave merger rate of compact binaries in galactic nuclei. We investigated this process by means of high accuracy few-body simulations, performed with a novel Monte Carlo approach. We find that, around a SgrA*-like SMBH, three-body encounters increase the number of mergers by a factor of 3. This occurs because close encounters can reorient binaries with respect to their orbital plane around the SMBH, increasing the number of Kozai-Lidov induced mergers. We obtain a binary black hole merger rate of ГMW = 1.6 × 10−6 yr−1 per Milky Way-like nucleus.

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