scholarly journals Uncertainties in tidal theory: Implications for bloated hot Jupiters

2010 ◽  
Vol 6 (S276) ◽  
pp. 248-251 ◽  
Author(s):  
Jérémy Leconte ◽  
Gilles Chabrier ◽  
Isabelle Baraffe
Keyword(s):  
Thermal Flux ◽  
Giant Planet ◽  
Theoretical Models ◽  
Mass Range ◽  
List Type ◽  
Phase Lag ◽  
Ohmic Dissipation ◽  
Tidal Theory ◽  
Strong Winds ◽  
Tidal Heating

AbstractThanks to the combination of transit photometry and radial velocity doppler measurements, we are now able to constrain theoretical models of the structure and evolution of objects in the whole mass range between icy giants and stars, including the giant planet/brown dwarf overlapping mass regime (Leconte et al. 2009). In the giant planet mass range, the significant fraction of planets showing a larger radius than predicted by the models suggests that a missing physical mechanism which is either injecting energy in the deep convective zone or reducing the net outward thermal flux is taking place in these objects. Several possibilities have been suggested for such a mechanism: •downward transport of kinetic energy originating from strong winds generated at the planet's surface (Showman & Guillot 2002),•enhanced opacity sources in hot-Jupiter atmospheres (Burrows et al. 2007),•ohmic dissipation in the ionized atmosphere (Batygin & Stevenson 2010),•(inefficient) layered or oscillatory convection in the planet's interior (Chabrier & Baraffe 2007),•Tidal heating due to circularization of the orbit, as originally suggested by Bodenheimer, Lin & Mardling (2001). Here we first review the differences between current models of tidal evolution and their uncertainties. We then revisit the viability of the tidal heating hypothesis using a tidal model which treats properly the highly eccentric and misaligned orbits commonly encountered in exoplanetary systems. We stress again that the low order expansions in eccentricity often used in constant phase lag tidal models (i.e. constant Q) necessarily yields incorrect results as soon as the (present or initial) eccentricity exceeds ~ 0.2, as can be rigorously demonstrated from Kepler's equations.

scholarly journals Habitability of the early Earth: liquid water under a faint young Sun facilitated by strong tidal heating due to a closer Moon

PalZ ◽  
2021 ◽  
Author(s):  
René Heller ◽  
Jan-Peter Duda ◽  
Max Winkler ◽  
Joachim Reitner ◽  
Laurent Gizon
Keyword(s):  
Liquid Water ◽  
Power Output ◽  
Mechanical Energy ◽  
Early Earth ◽  
Phase Lag ◽  
Geological Evidence ◽  
The Earth ◽  
Tidal Theory ◽  
Greenhouse Effects ◽  
Tidal Heating

AbstractGeological evidence suggests liquid water near the Earth’s surface as early as 4.4 gigayears ago when the faint young Sun only radiated about 70% of its modern power output. At this point, the Earth should have been a global snowball if it possessed atmospheric properties similar to those of the modern Earth. An extreme atmospheric greenhouse effect, an initially more massive Sun, release of heat acquired during the accretion process of protoplanetary material, and radioactivity of the early Earth material have been proposed as reservoirs or traps for heat. For now, the faint-young-Sun paradox persists as an important problem in our understanding of the origin of life on Earth. Here, we use the constant-phase-lag tidal theory to explore the possibility that the new-born Moon, which formed about 69 million years (Myr) after the ignition of the Sun, generated extreme tidal friction—and therefore, heat—in the Hadean and possibly the Archean Earth. We show that the Earth–Moon system has lost $${\sim }3~{\times }~10^{31}$$ ∼ 3 × 10 31  J (99% of its initial mechanical energy budget) as tidal heat. Tidal heating of $${\sim }10\,\mathrm{W\,m}^{-2}$$ ∼ 10 W m - 2 through the surface on a time scale of 100 Myr could have accounted for a temperature increase of up to $$5\,^\circ $$ 5 ∘ C on the early Earth. This heating effect alone does not solve the faint-young-Sun paradox but it could have played a key role in combination with other effects. Future studies of the interplay of tidal heating, the evolution of the solar power output, and the atmospheric (greenhouse) effects on the early Earth could help in solving the faint-young-Sun paradox.

Modelling of Io’s Atmosphere for the IVO Mission

2021 ◽  
Author(s):  
Peter Wurz ◽  
Audrey Vorburger ◽  
Alfred McEwen ◽  
Kathy Mandt ◽  
Ashley Davies ◽  
...  
Keyword(s):  
Mass Loss ◽  
Dynamic Range ◽  
Detection Threshold ◽  
Mass Range ◽  
Mission Design ◽  
Integration Time ◽  
Many Worlds ◽  
Initial State ◽  
Atmospheric Escape ◽  
Tidal Heating

<p>The Io Volcano Observer (IVO) is a proposed NASA Discovery-class mission (currently in Phase A), that would launch<span> in early 2029, arrive at </span> Jupiter in the early 2033, and perform ten flybys of Io while in Jupiter's orbit. IVO's mission motto is to 'follow the heat', shedding light onto tidal heating as a fundamental planetary process. Specifically, IVO will determine (i) how and where heat is generated in Io's interior, (ii) how heat is transported to the surface, and (iii) how Io has evolved with time. The answers to these questions will fill fundamental gaps in the current understanding of the evolution and habitability of many worlds across our Solar System and beyond where tidal heating plays a key role, and will give us insight into how early Earth, Moon, and Mars may have worked.</p><p>One of the five key science questions IVO will be addressing is determining Io's mass loss via atmospheric escape. Understanding Io's mass loss today will offer information on how the chemistry of Io has been altered from its initial state and would provide useful clues on how atmospheres on other bodies have evolved over time. IVO plans on measuring Io's mass loss in situ with the Ion and Neutral Mass Spectrometer (INMS), a successor to the instrument currently being built for the JUpiter Icy moons Explorer (JUICE). INMS will measure neutrals and ions in the mass range 1 – 300 u, with a mass resolution (M/ΔM) of 500, a dynamic range of > 10<sup>5</sup>, a detection threshold of 100 cm<sup>–3</sup> for an integration time of 5 s, and a cadence of 0.5 – 300 s per spectrum.</p><p>In preparation for IVO, we model atmospheric density profiles of species known and expected to be present on Io's surface from both measurements and previous modelling efforts. Based on the IVO mission design, we present three different measurement scenarios for INMS we expect to encounter at Io based on the planned flybys: (i) a purely sublimated atmosphere, (ii) the 'hot' atmosphere generated by lava fields, and (iii) the plume gases resulting from volcanic activity. We calculate the expected mass spectra to be recorded by INMS during these flybys for these atmospheric scenarios.</p>

scholarly journals The SHiP physics program

2018 ◽  
Vol 179 ◽  
pp. 01002
Author(s):  
Giovanni De Lellis
Keyword(s):  
Standard Model ◽  
Theoretical Models ◽  
Mass Range ◽  
Beyond The Standard Model ◽  
Beam Dump ◽  
Tau Neutrino ◽  
Physics Program ◽  
Weakly Coupled ◽  
Physics Potential ◽  
The Standard Model

The discovery of the Higgs boson has fully confirmed the Standard Model of particles and fields. Nevertheless, there are still fundamental phenomena, like the existence of dark matter and the baryon asymmetry of the Universe, which deserve an explanation that could come from the discovery of new particles. The SHiP experiment at CERN meant to search for very weakly coupled particles in the few GeV mass domain has been recently proposed. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored. A beam dump facility using high intensity 400 GeV protons is a copious source of such unknown particles in the GeV mass range. The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. Indeed, tau anti-neutrinos have not been directly observed so far. We report the physics potential of such an experiment including the tau neutrino magnetic moment.

scholarly journals What has quenched the massive spiral galaxies?

2020 ◽  
Vol 496 (1) ◽  
pp. L116-L121
Author(s):  
Yu Luo ◽  
Zongnan Li ◽  
Xi Kang ◽  
Zhiyuan Li ◽  
Peng Wang
Keyword(s):  
Black Holes ◽  
Spiral Galaxies ◽  
Theoretical Models ◽  
Mass Range ◽  
Sloan Digital Sky Survey ◽  
Analytical Models ◽  
Gas Content ◽  
Quenching Mechanism ◽  
Massive Black Holes ◽  
Hydrodynamical Simulations

ABSTRACT Quenched massive spiral galaxies have attracted great attention recently, as more data are available to constrain their environment and cold gas content. However, the quenching mechanism is still uncertain, as it depends on the mass range and baryon budget of the galaxy. In this letter, we report the identification of a rare population of very massive, quenched spiral galaxies with stellar mass ≳1011 M⊙ and halo mass ≳1013 M⊙ from the Sloan Digital Sky Survey at redshift z ∼ 0.1. Our CO observations using the IRAM (Institute for Radio Astronomy in the Millimeter Range) 30-m telescope show that these galaxies contain only a small amount of molecular gas. Similar galaxies are also seen in the state-of-the-art semi-analytical models and hydrodynamical simulations. It is found from these theoretical models that these quenched spiral galaxies harbour massive black holes, suggesting that feedback from the central black holes has quenched these spiral galaxies. This quenching mechanism seems to challenge the popular scenario of the co-evolution between massive black holes and massive bulges.

scholarly journals The Progenitor-Remnant Connection of Neutrino-Driven Supernovae Across the Stellar Mass Range

2016 ◽  
Vol 12 (S329) ◽  
pp. 74-77
Author(s):  
Thomas Ertl
Keyword(s):  
Neutron Star ◽  
Theoretical Models ◽  
Mass Range ◽  
Mass Function ◽  
Stellar Mass ◽  
Initial Mass Function ◽  
Solar Metallicity ◽  
Core Cooling ◽  
Two Parameters ◽  
Progenitor Stars

AbstractWe perform hydrodynamic supernova (SN) simulations in spherical symmetry for progenitor models with solar metallicity across the stellar mass range from 9.0 to 120 M⊙ to explore the progenitor-explosion and progenitor-remnant connections based on the neutrino-driven mechanism. We use an approximative treatment of neutrino transport and replace the high-density interior of the neutron star (NS) by an inner boundary condition based on an analytic proto-NS core-cooling model, whose free parameters are chosen to reproduce the observables of SN 1987A and the Crab SN for theoretical models of their progenitor stars.Judging the fate of a massive star, either a neutron star (NS) or a black hole (BH), solely by its structure prior to collapse has been ambiguous. Our work and previous attempts find a non-monotonic variation of successful and failed supernovae with zero-age main-sequence mass. We identify two parameters based on the “critical luminosity” concept for neutrino-driven explosions, which in combination allows for a clear separation of exploding and non-exploding cases.Continuing our simulations beyond shock break-out, we are able to determine nucleosynthesis, light curves, explosion energies, and remnant masses. The resulting NS initial mass function has a mean gravitational mass near 1.4 M⊙. The average BH mass is about 9 M⊙ if only the helium core implodes, and 14 M⊙ if the entire pre-SN star collapses. Only ~10% of SNe come from stars over 20 M⊙, and some of these are Type Ib or Ic.

Numerical and theoretical investigation of pulsatile turbulent channel flows

2016 ◽  
Vol 792 ◽  
pp. 98-133 ◽  
Author(s):  
Chenyang Weng ◽  
Susann Boij ◽  
Ardeshir Hanifi
Keyword(s):  
Shear Stress ◽  
Reynolds Shear Stress ◽  
Nonlinear Effects ◽  
Turbulent Channel Flow ◽  
Theoretical Models ◽  
Phase Lag ◽  
Reynolds Stresses ◽  
Turbulent Eddies ◽  
Turbulent Channel Flows ◽  
Physical Features

A turbulent channel flow subjected to imposed harmonic oscillations is studied by direct numerical simulation (DNS) and theoretical models. Simulations have been performed for different pulsation frequencies. The time- and phase-averaged data have been used to analyse the flow. The onset of nonlinear effects during the production of the perturbation Reynolds stresses is discussed based on the DNS data, and new physical features observed in the DNS are reported. A linear model proposed earlier by the present authors for the coherent perturbation Reynolds shear stress is reviewed and discussed in depth. The model includes the non-equilibrium effects during the response of the Reynolds stress to the imposed periodic shear straining, where a phase lag exists between the stress and the strain. To validate the model, the perturbation velocity and Reynolds shear stress from the model are compared with the DNS data. The performance of the model is found to be good in the frequency range where quasi-static assumptions are invalid. The viscoelastic characteristics of the turbulent eddies implied by the model are supported by the DNS data. Attempts to improve the model are also made by incorporating the DNS data in the model.

scholarly journals Structures of Dwarf Satellites of Milky Way-like Galaxies: Morphology, Scaling Relations, and Intrinsic Shapes

2021 ◽  
Vol 922 (2) ◽  
pp. 267
Author(s):  
Scott G. Carlsten ◽  
Jenny E. Greene ◽  
Johnny P. Greco ◽  
Rachael L. Beaton ◽  
Erin Kado-Fong
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Mass Range ◽  
Scaling Relations ◽  
Early Type ◽  
Late Type ◽  
Local Volume ◽  
Stellar Feedback ◽  
Oblate Spheroids ◽  
Tidal Heating

Abstract The structure of a dwarf galaxy is an important probe of the effects of stellar feedback and environment. Using an unprecedented sample of 223 low-mass satellites from the ongoing Exploration of Local Volume Satellites survey, we explore the structures of dwarf satellites in the mass range 105.5 < M ⋆ < 108.5 M ⊙. We survey satellites around 80% of the massive, M K < − 22.4 mag, hosts in the Local Volume (LV). Our sample of dwarf satellites is complete to luminosities of M V <−9 mag and surface brightness μ 0,V < 26.5 mag arcsec−2 within at least ∼200 projected kpc of the hosts. For this sample, we find a median satellite luminosity of M V = −12.4 mag, median size of r e = 560 pc, median ellipticity of ϵ = 0.30, and median Sérsic index of n = 0.72. We separate the satellites into late- and early-type (29.6% and 70.4%, respectively). The mass–size relations are very similar between them within ∼5%, which indicates that the quenching and transformation of a late-type dwarf into an early-type one involves only very mild size evolution. Considering the distribution of apparent ellipticities, we infer the intrinsic shapes of the early- and late-type samples. Combining with literature samples, we find that both types of dwarfs are described roughly as oblate spheroids that get more spherical at fainter luminosities, but early-types are always rounder at fixed luminosity. Finally, we compare the LV satellites with dwarf samples from the cores of the Virgo and Fornax clusters. We find that the cluster satellites show similar scaling relations to the LV early-type dwarfs but are roughly 10% larger at fixed mass, which we interpret as being due to tidal heating in the cluster environments. The dwarf structure results presented here are a useful reference for simulations of dwarf galaxy formation and the transformation of dwarf irregulars into spheroidals.

Phase Lag Model for Fluidelastic Instability in Square Cylinder Arrangement

2015 ◽  
Author(s):  
Mustapha Benaouicha ◽  
Elisabeth Longatte ◽  
Franck Baj
Keyword(s):  
Dynamic Instability ◽  
Fluid Velocity ◽  
Cross Flow ◽  
Theoretical Models ◽  
Phase Lag ◽  
Structure Parameters ◽  
Square Cylinder ◽  
Theoretical Formulation ◽  
Lag Model ◽  
Pitch Ratio

In this paper, a phase lag model is proposed in order to predict the fluid velocity threshold for fluidelastic dynamic instability of a square cylinder arrangement under cross flow. A theoretical formulation of a total damping, including the added damping in still fluid, the damping due to fluid flow and the damping derived from the phase shift between the fluid force and tube displacement, is given. A function of fluid and structure parameters, such as reduced velocity, pitch ratio and Scruton number, is thus obtained. It is shown that this function, taken as function of the reduced velocity variable, vanishes at the critical reduced velocity from which the fluidelastic dynamic instability of the tube occurs. Obviously, the value of the critical velocity is depending on other fluid-structure parameters. The obtained results are compared to experimental ones and those obtained from other theoretical models.

scholarly journals From the stellar properties of HD 219134 to the internal compositions of its transiting exoplanets

2019 ◽  
Vol 631 ◽  
pp. A92 ◽  
Author(s):  
R. Ligi ◽  
C. Dorn ◽  
A. Crida ◽  
Y. Lebreton ◽  
O. Creevey ◽  
...  
Keyword(s):  
Direct Determination ◽  
Evolutionary Model ◽  
Mass Range ◽  
Careful Analysis ◽  
Direct Estimate ◽  
Stellar Radius ◽  
Density Radius ◽  
Tidal Heating ◽  
Stellar Properties ◽  
Stellar Density

Context. The harvest of exoplanet discoveries has opened the area of exoplanet characterisation. But this cannot be achieved without a careful analysis of the host star parameters. Aims. The system of HD 219134 hosts two transiting exoplanets and at least two additional non-transiting exoplanets. We revisit the properties of this system using direct measurements of the stellar parameters to investigate the composition of the two transiting exoplanets. Methods. We used the VEGA/CHARA interferometer to measure the angular diameter of HD 219134. We also derived the stellar density from the transits light curves, which finally gives a direct estimate of the mass. This allowed us to infer the mass, radius, and density of the two transiting exoplanets of the system. We then used an inference model to obtain the internal parameters of these two transiting exoplanets. Results. We measure a stellar radius, density, and mass of R⋆ = 0.726 ± 0.014 R⊙, ρ⋆ = 1.82 ± 0.19 ρ⊙, and M⋆ = 0.696 ± 0.078 M⊙, respectively; there is a correlation of 0.46 between R⋆ and M⋆. This new mass is lower than that derived from the C2kSMO stellar evolutionary model, which provides a mass range of 0.755−0.810 (±0.040) M⊙. Moreover, we find that planet b and c have smaller radii than previously estimated of 1.500 ± 0.057 and 1.415 ± 0.049 R⊕ respectively; this clearly puts these planets out of the gap in the exoplanetary radii distribution and validates their super-Earth nature. Planet b is more massive than planet c, but the former is possibly less dense. We investigate whether this could be caused by partial melting of the mantle and find that tidal heating due to non-zero eccentricity of planet b may be powerful enough. Conclusions. The system of HD 219134 constitutes a very valuable benchmark for both stellar physics and exoplanetary science. The characterisation of the stellar hosts, and in particular the direct determination of the stellar density, radius, and mass, should be more extensively applied to provide accurate exoplanets properties and calibrate stellar models.

Analysis of the Transfer Function of Large and Small Premixed Laminar Conical Flames

2017 ◽  
Author(s):  
R. Gaudron ◽  
M. Gatti ◽  
C. Mirat ◽  
T. Schuller
Keyword(s):  
Transfer Function ◽  
Practical Interest ◽  
Theoretical Models ◽  
Phase Lag ◽  
Velocity Perturbation ◽  
Flow Perturbation ◽  
Half Angle ◽  
Premixed Laminar ◽  
Analytical Expressions ◽  
Weak Influence

The Flame Transfer Function (FTF) of premixed laminar conical flames submitted to flowrate modulations is a configuration of fundamental and practical interest for improving the design of thermo-acoustically stable low power burners. Many theoretical models were developed for relatively large single flames based on labscale experiments, while most domestic and industrial burners operate with a collection of small injectors. Measurements of the FTF of laminar premixed methane/air conical flames are compared with analytical expressions deduced from kinematic descriptions of flame wrinkling when the burner size is reduced. The flame aspect ratio is kept constant corresponding to a flame tip half-angle α = 14.47° and the radius of the injector is reduced from R = 11 mm to R = 1.5 mm. Three different velocity perturbation models are tested, with and without an additional model accounting for the dynamics of the flame anchoring point. For the largest flames R = 11 mm and 7 mm, the best agreement is found for a FTF model with an incompressible velocity disturbance in the fresh reactants stream. The anchoring point dynamics has only a weak influence on the FTF gain and phase-lag plots of these flames. For the smallest flames (R = 1.5 mm), a FTF model based on a uniform flow perturbation yields the best match with experiments for the phase-lag plot, but none of the three velocity perturbation models reproduce the FTF gain evolution as measured in experiments. Including the contribution of the anchoring point dynamics to the FTF significantly changes the FTF gain predictions, but it does not allow to reproduce the main features observed in the measured gain curves and the phase-lag predictions worsen. It is concluded that an additional modeling effort is needed to adequatedly reproduce the FTF of small premixed laminar conical flames.

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