pubint0.bib
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@article{2018A&A...613A..68G,
author = {{Grimm}, S.~L. and {Demory}, B.-O. and {Gillon}, M. and {Dorn}, C. and
{Agol}, E. and {Burdanov}, A. and {Delrez}, L. and {Sestovic}, M. and
{Triaud}, A.~H.~M.~J. and {Turbet}, M. and {Bolmont}, {\'E}. and
{Caldas}, A. and {de Wit}, J. and {Jehin}, E. and {Leconte}, J. and
{Raymond}, S.~N. and {Van Grootel}, V. and {Burgasser}, A.~J. and
{Carey}, S. and {Fabrycky}, D. and {Heng}, K. and {Hernandez}, D.~M. and
{Ingalls}, J.~G. and {Lederer}, S. and {Selsis}, F. and {Queloz}, D.
},
title = {{The nature of the TRAPPIST-1 exoplanets}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1802.01377},
primaryclass = {astro-ph.EP},
keywords = {methods: numerical, planets and satellites: detection, planets and satellites: individual: TRAPPIST-1},
year = 2018,
volume = 613,
eid = {A68},
pages = {A68},
abstract = {{Context. The TRAPPIST-1 system hosts seven Earth-sized, temperate
exoplanets orbiting an ultra-cool dwarf star. As such, it represents a
remarkable setting to study the formation and evolution of terrestrial
planets that formed in the same protoplanetary disk. While the sizes of
the TRAPPIST-1 planets are all known to better than 5\% precision, their
densities have significant uncertainties (between 28\% and 95\%) because
of poor constraints on the planet's masses.
Aims: The goal of
this paper is to improve our knowledge of the TRAPPIST-1 planetary
masses and densities using transit-timing variations (TTVs). The
complexity of the TTV inversion problem is known to be particularly
acute in multi-planetary systems (convergence issues, degeneracies and
size of the parameter space), especially for resonant chain systems such
as TRAPPIST-1.
Methods: To overcome these challenges, we have
used a novel method that employs a genetic algorithm coupled to a full
N-body integrator that we applied to a set of 284 individual transit
timings. This approach enables us to efficiently explore the parameter
space and to derive reliable masses and densities from TTVs for all
seven planets.
Results: Our new masses result in a five- to
eight-fold improvement on the planetary density uncertainties, with
precisions ranging from 5\% to 12\%. These updated values provide new
insights into the bulk structure of the TRAPPIST-1 planets. We find that
TRAPPIST-1 c and e likely have largely rocky interiors, while planets b,
d, f, g, and h require envelopes of volatiles in the form of thick
atmospheres, oceans, or ice, in most cases with water mass fractions
less than 5\%.
}},
doi = {10.1051/0004-6361/201732233},
adsurl = {https://ui.adsabs.harvard.edu/abs/2018A%26A...613A..68G},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2018NatGe..11..168L,
author = {{Leconte}, J.},
title = {{Continuous reorientation of synchronous terrestrial planets due to mantle convection}},
journal = {Nature Geoscience},
archiveprefix = {arXiv},
eprint = {1809.01150},
primaryclass = {astro-ph.EP},
year = 2018,
volume = 11,
pages = {168-172},
abstract = {{Many known rocky exoplanets are thought to have been spun down by tidal
interactions to a state of synchronous rotation, in which a planet's
period of rotation is equal to that of its orbit around its host star.
Investigations into atmospheric and surface processes occurring on such
exoplanets thus commonly assume that day and night sides are fixed with
respect to the surface over geological timescales. Here we use an
analytical model to show that true polar wander{\mdash}where a planetary
body's spin axis shifts relative to its surface because of changes in
mass distribution{\mdash}can continuously reorient a synchronous rocky
exoplanet. As occurs on Earth, we find that even weak mantle convection
in a rocky exoplanet can produce density heterogeneities within the
mantle sufficient to reorient the planet. Moreover, we show that this
reorientation is made very efficient by the slower rotation rate of a
synchronous planet when compared with Earth, which limits the
stabilizing effect of rotational and tidal deformations. Furthermore, a
relatively weak lithosphere limits its ability to support remnant loads
and stabilize against reorientation. Although uncertainties exist
regarding the mantle and lithospheric evolution of these worlds, we
suggest that the axes of smallest and largest moment of inertia of
synchronous exoplanets with active mantle convection change continuously
over time, but remain closely aligned with the star-planet and orbital
axes, respectively.
}},
doi = {10.1038/s41561-018-0071-2},
adsurl = {https://ui.adsabs.harvard.edu/abs/2018NatGe..11..168L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2018ApJ...853L..30L,
author = {{Leconte}, J.},
title = {{Why Compositional Convection Cannot Explain Substellar Objects{\rsquo} Sharp Spectral-type Transitions}},
journal = {\apjl},
archiveprefix = {arXiv},
eprint = {1801.08142},
primaryclass = {astro-ph.SR},
keywords = {brown dwarfs, hydrodynamics, planets and satellites: atmospheres, planets and satellites: gaseous planets},
year = 2018,
volume = 853,
eid = {L30},
pages = {L30},
abstract = {{As brown dwarfs and young giant planets cool down, they are known to
experience various chemical transitions{\mdash}for example, from $\{$CO$\}$
rich L-dwarfs to methane rich T-dwarfs. Those chemical transitions are
accompanied by spectral transitions with sharpness that cannot be
explained by chemistry alone. In a series of articles, Tremblin et al.
proposed that some of the yet-unexplained features associated with these
transitions could be explained by a reduction of the thermal gradient
near the photosphere. To explain, in turn, this more isothermal profile,
they invoke the presence of an instability analogous to fingering
convection{\mdash}compositional convection{\mdash}triggered by the change
in mean molecular weight of the gas due to the chemical transitions
mentioned above. In this Letter, we use existing arguments to
demonstrate that any turbulent transport, if present, would in fact
increase the thermal gradient. This misinterpretation comes from the
fact that turbulence mixes/homogenizes entropy (potential temperature)
instead of temperature. So, while increasing transport, turbulence in an
initially stratified atmosphere actually carries energy downward,
whether it is due to fingering or any other type of compositional
convection. These processes therefore cannot explain the features
observed along the aforementioned transitions by reducing the thermal
gradient in the atmosphere of substellar objects. Understanding the
microphysical and dynamical properties of clouds at these transitions
thus probably remains our best way forward.
}},
doi = {10.3847/2041-8213/aaaa61},
adsurl = {https://ui.adsabs.harvard.edu/abs/2018ApJ...853L..30L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2017Icar..291....1C,
author = {{Cavalié}, T. and {Venot}, O. and {Selsis}, F. and {Hersant}, F. and
{Hartogh}, P. and {Leconte}, J.},
title = {{Thermochemistry and vertical mixing in the tropospheres of Uranus and Neptune: How convection inhibition can affect the derivation of deep oxygen abundances}},
journal = {\icarus},
archiveprefix = {arXiv},
eprint = {1703.04358},
primaryclass = {astro-ph.EP},
keywords = {Abundances, Atmospheres, Interior, Uranus, Neptune},
year = 2017,
volume = 291,
pages = {1-16},
abstract = {{Thermochemical models have been used in the past to constrain the deep
oxygen abundance in the gas and ice giant planets from tropospheric CO
spectroscopic measurements. Knowing the oxygen abundance of these
planets is a key to better understand their formation. These models have
widely used dry and/or moist adiabats to extrapolate temperatures from
the measured values in the upper troposphere down to the level where the
thermochemical equilibrium between H$_{2}$O and CO is established.
The mean molecular mass gradient produced by the condensation of
H$_{2}$O stabilizes the atmosphere against convection and results
in a vertical thermal profile and H$_{2}$O distribution that
departs significantly from previous estimates. We revisit O/H estimates
using an atmospheric structure that accounts for the inhibition of the
convection by condensation. We use a thermochemical network and the
latest observations of CO in Uranus and Neptune to calculate the
internal oxygen enrichment required to satisfy both these new estimates
of the thermal profile and the observations. We also present the current
limitations of such modeling.
}},
doi = {10.1016/j.icarus.2017.03.015},
adsurl = {https://ui.adsabs.harvard.edu/abs/2017Icar..291....1C},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2017A&A...598A..98L,
author = {{Leconte}, J. and {Selsis}, F. and {Hersant}, F. and {Guillot}, T.
},
title = {{Condensation-inhibited convection in hydrogen-rich atmospheres . Stability against double-diffusive processes and thermal profiles for Jupiter, Saturn, Uranus, and Neptune}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1610.05506},
primaryclass = {astro-ph.EP},
keywords = {planets and satellites: atmospheres, convection},
year = 2017,
volume = 598,
eid = {A98},
pages = {A98},
abstract = {{In an atmosphere, a cloud condensation region is characterized by a
strong vertical gradient in the abundance of the related condensing
species. On Earth, the ensuing gradient of mean molecular weight has
relatively few dynamical consequences because N$_{2}$ is heavier
than water vapor, so that only the release of latent heat significantly
impacts convection. On the contrary, in a hydrogen dominated atmosphere
(e.g., giant planets), all condensing species are significantly heavier
than the background gas. This can stabilize the atmosphere against
convection near a cloud deck if the enrichment in the given species
exceeds a critical threshold. This raises two questions. What is
transporting energy in such a stabilized layer, and how affected can the
thermal profile of giant planets be? To answer these questions, we first
carry out a linear analysis of the convective and double-diffusive
instabilities in a condensable medium showing that an efficient
condensation can suppress double-diffusive convection. This suggests
that a stable radiative layer can form near a cloud condensation level,
leading to an increase in the temperature of the deep adiabat. Then, we
investigate the impact of the condensation of the most abundant species
(water) with a steady-state atmosphere model. Compared to standard
models, the temperature increase can reach several hundred degrees at
the quenching depth of key chemical tracers. Overall, this effect could
have many implications for our understanding of the dynamical and
chemical state of the atmosphere of giant planets, for their future
observations (with Juno for example), and for their internal evolution.
}},
doi = {10.1051/0004-6361/201629140},
adsurl = {https://ui.adsabs.harvard.edu/abs/2017A%26A...598A..98L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2017A&A...597A..94C,
author = {{Chiavassa}, A. and {Caldas}, A. and {Selsis}, F. and {Leconte}, J. and
{Von Paris}, P. and {Bordé}, P. and {Magic}, Z. and {Collet}, R. and
{Asplund}, M.},
title = {{Measuring stellar granulation during planet transits}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1609.08966},
primaryclass = {astro-ph.EP},
keywords = {planet-star interactions, stars: activity, techniques: photometric, stars: atmospheres, hydrodynamics, radiative transfer},
year = 2017,
volume = 597,
eid = {A94},
pages = {A94},
abstract = {{Context. Stellar activity and convection-related surface structures
might cause bias in planet detection and characterization that use these
transits. Surface convection simulations help to quantify the
granulation signal.
Aims: We used realistic three-dimensional
(3D) radiative hydrodynamical (RHD) simulations from the Stagger grid
and synthetic images computed with the radiative transfer code Optim3D
to model the transits of three prototype planets: a hot Jupiter, a hot
Neptune, and a terrestrial planet.
Methods: We computed intensity
maps from RHD simulations of the Sun and a K-dwarf star at different
wavelength bands from optical to far-infrared that cover the range of
several ground- and space-based telescopes which observe exoplanet
transits. We modeled the transit using synthetic stellar-disk images
obtained with a spherical-tile imaging method and emulated the temporal
variation of the granulation intensity generating random images covering
a granulation time-series of 13.3 h. We measured the contribution of the
stellar granulation on the light curves during the planet transit.
Results: We identified two types of granulation noise that act
simultaneously during the planet transit: (I) the intrinsic change in
the granulation pattern with timescale (e.g., 10 min for solar-type
stars assumed in this work) is smaller than the usual planet transit (
hours as in our prototype cases); and (II) the fact that the transiting
planet occults isolated regions of the photosphere that differ in local
surface brightness as a result of convective-related surface structures.
First, we showed that our modeling approach returns granulation
timescale fluctuations that are comparable with what has been observed
for the Sun. Then, our statistical approach shows that the granulation
pattern of solar and K-dwarf-type stars have a non-negligible effect of
the light curve depth during the transit, and, consequentially on the
determination of the planet transit parameters such as the planet radius
(up to 0.90\% and 0.47\% for terrestrial and gaseous planets,
respectively). We also showed that larger (or smaller) orbital
inclination angles with respect to values corresponding to transit at
the stellar center display a shallower transit depth and longer ingress
and egress times, but also granulation fluctuations that are correlated
to the center-to-limb variation: they increase (or decrease) the value
of the inclination, which amplifies the fluctuations. The granulation
noise appears to be correlated among the different wavelength ranges
either in the visible or in the infrared regions.
Conclusions:
The prospects for planet detection and characterization with transiting
methods are excellent with access to large amounts of data for stars.
The granulation has to be considered as an intrinsic uncertainty (as a
result of stellar variability) on the precise measurements of exoplanet
transits of planets. The full characterization of the granulation is
essential for determining the degree of uncertainty on the planet
parameters. In this context, the use of 3D RHD simulations is important
to measure the convection-related fluctuations. This can be achieved by
performing precise and continuous observations of stellar photometry and
radial velocity, as we explained with RHD simulations, before, after,
and during the transit periods.
}},
doi = {10.1051/0004-6361/201528018},
adsurl = {https://ui.adsabs.harvard.edu/abs/2017A%26A...597A..94C},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2015ExA....40..329T,
author = {{Tinetti}, G. and {Drossart}, P. and {Eccleston}, P. and {Hartogh}, P. and
{Isaak}, K. and {Linder}, M. and {Lovis}, C. and {Micela}, G. and
{Ollivier}, M. and {Puig}, L. and {Ribas}, I. and {Snellen}, I. and
{Swinyard}, B. and {Allard}, F. and {Barstow}, J. and {Cho}, J. and
{Coustenis}, A. and {Cockell}, C. and {Correia}, A. and {Decin}, L. and
{de Kok}, R. and {Deroo}, P. and {Encrenaz}, T. and {Forget}, F. and
{Glasse}, A. and {Griffith}, C. and {Guillot}, T. and {Koskinen}, T. and
{Lammer}, H. and {Leconte}, J. and {Maxted}, P. and {Mueller-Wodarg}, I. and
{Nelson}, R. and {North}, C. and {Pallé}, E. and {Pagano}, I. and
{Piccioni}, G. and {Pinfield}, D. and {Selsis}, F. and {Sozzetti}, A. and
{Stixrude}, L. and {Tennyson}, J. and {Turrini}, D. and {Zapatero-Osorio}, M. and
{Beaulieu}, J.-P. and {Grodent}, D. and {Guedel}, M. and {Luz}, D. and
{N{\o}rgaard-Nielsen}, H.~U. and {Ray}, T. and {Rickman}, H. and
{Selig}, A. and {Swain}, M. and {Banaszkiewicz}, M. and {Barlow}, M. and
{Bowles}, N. and {Branduardi-Raymont}, G. and {du Foresto}, V.~C. and
{Gerard}, J.-C. and {Gizon}, L. and {Hornstrup}, A. and {Jarchow}, C. and
{Kerschbaum}, F. and {Kovacs}, G. and {Lagage}, P.-O. and {Lim}, T. and
{Lopez-Morales}, M. and {Malaguti}, G. and {Pace}, E. and {Pascale}, E. and
{Vandenbussche}, B. and {Wright}, G. and {Ramos Zapata}, G. and
{Adriani}, A. and {Azzollini}, R. and {Balado}, A. and {Bryson}, I. and
{Burston}, R. and {Colomé}, J. and {Crook}, M. and {Di Giorgio}, A. and
{Griffin}, M. and {Hoogeveen}, R. and {Ottensamer}, R. and {Irshad}, R. and
{Middleton}, K. and {Morgante}, G. and {Pinsard}, F. and {Rataj}, M. and
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{Winter}, B. and {Abe}, L. and {Abreu}, M. and {Achilleos}, N. and
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{Agundez}, M. and {Alard}, C. and {Alcala}, J. and {Allende Prieto}, C. and
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},
title = {{The EChO science case}},
journal = {Experimental Astronomy},
archiveprefix = {arXiv},
eprint = {1502.05747},
primaryclass = {astro-ph.EP},
keywords = {Exoplanets, Spectroscopy, Atmospheric science, IR astronomy, Space missions},
year = 2015,
volume = 40,
pages = {329-391},
abstract = {{The discovery of almost two thousand exoplanets has revealed an
unexpectedly diverse planet population. We see gas giants in few-day
orbits, whole multi-planet systems within the orbit of Mercury, and new
populations of planets with masses between that of the Earth and
Neptune{\mdash}all unknown in the Solar System. Observations to date have
shown that our Solar System is certainly not representative of the
general population of planets in our Milky Way. The key science
questions that urgently need addressing are therefore: What are
exoplanets made of? Why are planets as they are? How do planetary
systems work and what causes the exceptional diversity observed as
compared to the Solar System? The EChO (Exoplanet Characterisation
Observatory) space mission was conceived to take up the challenge to
explain this diversity in terms of formation, evolution, internal
structure and planet and atmospheric composition. This requires in-depth
spectroscopic knowledge of the atmospheres of a large and well-defined
planet sample for which precise physical, chemical and dynamical
information can be obtained. In order to fulfil this ambitious
scientific program, EChO was designed as a dedicated survey mission for
transit and eclipse spectroscopy capable of observing a large, diverse
and well-defined planet sample within its 4-year mission lifetime. The
transit and eclipse spectroscopy method, whereby the signal from the
star and planet are differentiated using knowledge of the planetary
ephemerides, allows us to measure atmospheric signals from the planet at
levels of at least 10$^{-4}$ relative to the star. This can only
be achieved in conjunction with a carefully designed stable payload and
satellite platform. It is also necessary to provide broad instantaneous
wavelength coverage to detect as many molecular species as possible, to
probe the thermal structure of the planetary atmospheres and to correct
for the contaminating effects of the stellar photosphere. This requires
wavelength coverage of at least 0.55 to 11 {$\mu$}m with a goal of covering
from 0.4 to 16 {$\mu$}m. Only modest spectral resolving power is needed,
with R \~{} 300 for wavelengths less than 5 {$\mu$}m and R \~{} 30 for
wavelengths greater than this. The transit spectroscopy technique means
that no spatial resolution is required. A telescope collecting area of
about 1 m$^{2}$ is sufficiently large to achieve the necessary
spectro-photometric precision: for the Phase A study a 1.13
m$^{2}$ telescope, diffraction limited at 3 {$\mu$}m has been
adopted. Placing the satellite at L2 provides a cold and stable thermal
environment as well as a large field of regard to allow efficient
time-critical observation of targets randomly distributed over the sky.
EChO has been conceived to achieve a single goal: exoplanet
spectroscopy. The spectral coverage and signal-to-noise to be achieved
by EChO, thanks to its high stability and dedicated design, would be a
game changer by allowing atmospheric composition to be measured with
unparalleled exactness: at least a factor 10 more precise and a factor
10 to 1000 more accurate than current observations. This would enable
the detection of molecular abundances three orders of magnitude lower
than currently possible and a fourfold increase from the handful of
molecules detected to date. Combining these data with estimates of
planetary bulk compositions from accurate measurements of their radii
and masses would allow degeneracies associated with planetary interior
modelling to be broken, giving unique insight into the interior
structure and elemental abundances of these alien worlds. EChO would
allow scientists to study exoplanets both as a population and as
individuals. The mission can target super-Earths, Neptune-like, and
Jupiter-like planets, in the very hot to temperate zones (planet
temperatures of 300-3000 K) of F to M-type host stars. The EChO core
science would be delivered by a three-tier survey. The EChO Chemical
Census: This is a broad survey of a few-hundred exoplanets, which allows
us to explore the spectroscopic and chemical diversity of the exoplanet
population as a whole. The EChO Origin: This is a deep survey of a
subsample of tens of exoplanets for which significantly higher signal to
noise and spectral resolution spectra can be obtained to explain the
origin of the exoplanet diversity (such as formation mechanisms,
chemical processes, atmospheric escape). The EChO Rosetta Stones: This
is an ultra-high accuracy survey targeting a subsample of select
exoplanets. These will be the bright ``benchmark'' cases for which a large
number of measurements would be taken to explore temporal variations,
and to obtain two and three dimensional spatial information on the
atmospheric conditions through eclipse-mapping techniques. If EChO were
launched today, the exoplanets currently observed are sufficient to
provide a large and diverse sample. The Chemical Census survey would
consist of $\gt$ 160 exoplanets with a range of planetary sizes,
temperatures, orbital parameters and stellar host properties.
Additionally, over the next 10 years, several new ground- and
space-based transit photometric surveys and missions will come on-line
(e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on
finding bright, nearby systems. The current rapid rate of discovery
would allow the target list to be further optimised in the years prior
to EChO's launch and enable the atmospheric characterisation of hundreds
of planets.
}},
doi = {10.1007/s10686-015-9484-8},
adsurl = {https://ui.adsabs.harvard.edu/abs/2015ExA....40..329T},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2014RSPTA.37230084F,
author = {{Forget}, F. and {Leconte}, J.},
title = {{Possible climates on terrestrial exoplanets}},
journal = {Philosophical Transactions of the Royal Society of London Series A},
archiveprefix = {arXiv},
eprint = {1311.3101},
primaryclass = {astro-ph.EP},
year = 2014,
volume = 372,
pages = {20130084-20130084},
abstract = {{What kind of environment may exist on terrestrial planets around other
stars? In spite of the lack of direct observations, it may not be
premature to speculate on exoplanetary climates, for instance to
optimize future telescopic observations, or to assess the probability of
habitable worlds. To first order, climate primarily depends on 1) The
atmospheric composition and the volatile inventory; 2) The incident
stellar flux; 3) The tidal evolution of the planetary spin, which can
notably lock a planet with a permanent night side. The atmospheric
composition and mass depends on complex processes which are difficult to
model: origins of volatile, atmospheric escape, geochemistry,
photochemistry. We discuss physical constraints which can help us to
speculate on the possible type of atmosphere, depending on the planet
size, its final distance for its star and the star type. Assuming that
the atmosphere is known, the possible climates can be explored using
Global Climate Models analogous to the ones developed to simulate the
Earth as well as the other telluric atmospheres in the solar system. Our
experience with Mars, Titan and Venus suggests that realistic climate
simulators can be developed by combining components like a ``dynamical
core'', a radiative transfer solver, a parametrisation of subgrid-scale
turbulence and convection, a thermal ground model, and a volatile phase
change code. On this basis, we can aspire to build reliable climate
predictors for exoplanets. However, whatever the accuracy of the models,
predicting the actual climate regime on a specific planet will remain
challenging because climate systems are affected by strong positive
destabilizing feedbacks (such as runaway glaciations and runaway
greenhouse effect). They can drive planets with very similar forcing and
volatile inventory to completely different states.
}},
doi = {10.1098/rsta.2013.0084},
adsurl = {https://ui.adsabs.harvard.edu/abs/2014RSPTA.37230084F},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2013NatGe...6..347L,
author = {{Leconte}, J. and {Chabrier}, G.},
title = {{Layered convection as the origin of Saturn's luminosity anomaly}},
journal = {Nature Geoscience},
archiveprefix = {arXiv},
eprint = {1304.6184},
primaryclass = {astro-ph.EP},
year = 2013,
volume = 6,
pages = {347-350},
abstract = {{As the giant planets of our Solar System continue to cool and contract,
they radiate more energy than they receive from the Sun. A giant
planet's cooling rate, luminosity and temperature at a given age can be
determined using the first and second principles of thermodynamics.
Measurements of Saturn's infrared luminosity, however, reveal that
Saturn is significantly brighter than predicted for its age. This excess
luminosity has been attributed to the immiscibility of helium in
Saturn's hydrogen-rich envelope, which leads to rains of helium-rich
droplets. Existing calculations of Saturn's evolution, however, suggest
that the energy released by helium rains might be insufficient to
resolve the luminosity puzzle. Here we demonstrate, using
semi-analytical models of planetary thermal evolution, that the cooling
of Saturn's interior is significantly slower in the presence of layered
convection generated--like in Earth's oceans--by a compositional
gradient. We find that layered convection can explain Saturn's present
luminosity for a wide range of initial energy configurations without
invoking any additional energy source. Our findings suggest that the
interior structure, composition and thermal evolution of giant planets
in our Solar System and beyond may be more complex than the conventional
approximation of giant planets as homogeneous adiabatic bodies.
}},
doi = {10.1038/ngeo1791},
adsurl = {https://ui.adsabs.harvard.edu/abs/2013NatGe...6..347L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2012A&A...540A..20L,
author = {{Leconte}, J. and {Chabrier}, G.},
title = {{A new vision of giant planet interiors: Impact of double diffusive convection}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1201.4483},
primaryclass = {astro-ph.EP},
keywords = {Planets and satellites: general, Planets and satellites: composition, Planets and satellites: interiors, Planets and satellites: individual: Jupiter, Planets and satellites: individual: Saturn},
year = 2012,
volume = 540,
eid = {A20},
pages = {A20},
abstract = {{While conventional interior models for Jupiter and Saturn are based on
the simplistic assumption of a solid core surrounded by a homogeneous
gaseous envelope, we have derived new models with an inhomogeneous
distribution of heavy elements within these planets. Such a
compositional gradient hampers large-scale convection that turns into
double-diffusive convection, yielding an inner thermal profile that
departs from the traditionally assumed adiabatic interior and affecting
these planets heat content and cooling history. To address this problem,
we have developed an analytical approach to describe layered
double-diffusive convection and apply this formalism to solar system
gaseous giant planet interiors. These models satisfy all observational
constraints and yield values for the metal enrichment of our gaseous
giants that are up to 30\% to 60\% higher than previously thought. The
models also constrain the size of the convective layers within the
planets. Because the heavy elements tend to be redistributed within the
gaseous envelope, the models predict smaller than usual central cores
inside Saturn and Jupiter, with possibly no core for the latter. These
models open a new window and raise new challenges to our understanding
of the internal structure of giant (solar and extrasolar) planets, in
particular on how to determine their heavy material content, a key
diagnostic for planet formation theories.
}},
doi = {10.1051/0004-6361/201117595},
adsurl = {https://ui.adsabs.harvard.edu/abs/2012A%26A...540A..20L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2011A&A...535A..94B,
author = {{Bolmont}, E. and {Raymond}, S.~N. and {Leconte}, J.},
title = {{Tidal evolution of planets around brown dwarfs}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1109.2906},
primaryclass = {astro-ph.EP},
keywords = {brown dwarfs, stars: rotation, planets and satellites: dynamical evolution and stability, planet-star interactions, astrobiology},
year = 2011,
volume = 535,
eid = {A94},
pages = {A94},
abstract = {{Context. The tidal evolution of planets orbiting brown dwarfs (BDs)
presents an interesting case study because BDs' terrestrial planet
forming region is located extremely close-in. In fact, the habitable
zones of BDs range from roughly 0.001 to 0.03 AU and for the lowest-mass
BDs are located interior to the Roche limit.
Aims: In contrast
with stars, BDs spin up as they age. Thus, the corotation distance moves
inward. This has important implications for the tidal evolution of
planets around BDs.
Methods: We used a standard equilibrium tidal
model to compute the orbital evolution of a large ensemble of planet-BD
systems. We tested the effect of numerous parameters such as the initial
semi-major axis and eccentricity, the rotation period of the BD, the
masses of both the BD and planet, and the tidal dissipation factors.
Results: We find that all planets that form at or beyond the
corotation distance and with initial eccentricities smaller than \~{}0.1
are repelled from the BD. Some planets initially interior to corotation
can survive if their inward tidal evolution is slower than the BD's spin
evolution, but most initially close-in planets fall onto the BD.
Conclusions: We find that the most important parameter for the tidal
evolution is the initial orbital distance with respect to the corotation
distance. Some planets can survive in the habitable zone for Gyr
timescales, although in many cases the habitable zone moves inward past
the planet's orbit in just tens to hundreds of Myr. Surviving planets
can have orbital periods of less than 10 days (as small as 10 h), so
they could be observable by transit.
}},
doi = {10.1051/0004-6361/201117734},
adsurl = {https://ui.adsabs.harvard.edu/abs/2011A%26A...535A..94B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2010A&A...516A..64L,
author = {{Leconte}, J. and {Chabrier}, G. and {Baraffe}, I. and {Levrard}, B.
},
title = {{Is tidal heating sufficient to explain bloated exoplanets? Consistent calculations accounting for finite initial eccentricity}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1004.0463},
primaryclass = {astro-ph.EP},
keywords = {brown dwarfs, planet-star interactions, planets and satellites: dynamical evolution and stability, planets and satellites: general},
year = 2010,
volume = 516,
eid = {A64},
pages = {A64},
abstract = {{We present the consistent evolution of short-period exoplanets coupling
the tidal and gravothermal evolution of the planet. Contrarily to
previous similar studies, our calculations are based on the complete
tidal evolution equations of the Hut (1981) model, valid at any order in
eccentricity, obliquity and spin. We demonstrate both analytically and
numerically that except if the system was formed with a nearly circular
orbit (e {\lap} 0.2), consistently solving the complete tidal equations
is mandatory to derive correct tidal evolution histories. We show that
calculations based on tidal models truncated at 2nd order in
eccentricity, as done in all previous studies, lead to quantitatively
and sometimes even qualitatively erroneous tidal evolutions. As a
consequence, tidal energy dissipation rates are severely underestimated
in all these calculations and the characteristic timescales for the
various orbital parameters evolutions can be wrong by up to three orders
of magnitude. These discrepancies can by no means be justified by
invoking the uncertainty in the tidal quality factors. Based on these
complete, consistent calculations, we revisit the viability of the tidal
heating hypothesis to explain the anomalously large radius of transiting
giant planets. We show that even though tidal dissipation does provide a
substantial contribution to the planet's heat budget and can explain
some of the moderately bloated hot-Jupiters, this mechanism can not
explain alone the properties of the most inflated objects, including HD
209 458 b. Indeed, solving the complete tidal equations shows that
enhanced tidal dissipation and thus orbit circularization occur too
early during the planet's evolution to provide enough extra energy at
the present epoch. In that case either a third, so far undetected,
low-mass companion must be present to keep exciting the eccentricity of
the giant planet, or other mechanisms - stellar irradiation induced
surface winds dissipating in the planet's tidal bulges and thus reaching
the convective layers, inefficient flux transport by convection in the
planet's interior - must be invoked, together with tidal dissipation, to
provide all the pieces of the abnormally large exoplanet puzzle.
}},
doi = {10.1051/0004-6361/201014337},
adsurl = {https://ui.adsabs.harvard.edu/abs/2010A%26A...516A..64L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2009A&A...506..385L,
author = {{Leconte}, J. and {Baraffe}, I. and {Chabrier}, G. and {Barman}, T. and
{Levrard}, B.},
title = {{Structure and evolution of the first CoRoT exoplanets: probing the brown dwarf/planet overlapping mass regime}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {0907.2669},
primaryclass = {astro-ph.EP},
keywords = {stars: low-mass, brown dwarfs, stars: planetary systems},
year = 2009,
volume = 506,
pages = {385-389},
abstract = {{We present detailed structure and evolution calculations for the first
transiting extrasolar planets discovered by the space-based CoRoT
mission. Comparisons between theoretical and observed radii provide
information on the internal composition of the CoRoT objects. We
distinguish three different categories of planets emerging from these
discoveries and from previous ground-based surveys: (i) planets
explained by standard planetary models including irradiation; (ii)
abnormally bloated planets; and (iii) massive objects belonging to the
overlapping mass regime between planets and brown dwarfs. For the second
category, we show that tidal heating can explain the relevant CoRoT
objects, providing non-zero eccentricities. We stress that the usual
assumption of a quick circularization of the orbit by tides, as usually
done in transit light curve analysis, is not justified a priori, as
suggested recently by Levrard et al. (2009), and that eccentricity
analysis should be carefully redone for some observations. Finally,
special attention is devoted to CoRoT-3b and to the identification of
its very nature: giant planet or brown dwarf? The radius determination
of this object confirms the theoretical mass-radius predictions for
gaseous bodies in the substellar regime but, given the present
observational uncertainties, does not allow an unambiguous
identification of its very nature. This opens the avenue, however, to an
observational identification of these two distinct astrophysical
populations, brown dwarfs and giant planets, in their overlapping mass
range, as done for the case of the 8 Jupiter-mass object Hat-P-2b.
According to the presently published error bars for the radius
determination and to our present theoretical description of planet
structure and evolution, the high mean density of this object requires a
substantial metal enrichment of the interior and is inconsistent at
about the 2-sigma limit with the expected radius of a solar-metallicity
brown dwarf. Within the aforementioned observational and theoretical
determinations, this allows a clear identification of its planetary
nature, suggesting that planets may form up to at least 8 Jupiter
masses.
}},
doi = {10.1051/0004-6361/200911896},
adsurl = {https://ui.adsabs.harvard.edu/abs/2009A%26A...506..385L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}