pub2016.bib
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@comment{{Command line: bib2bib -c 'not journal:"Discussions"' -c 'not title:"Correction to"' -c year=2016 -c $type="ARTICLE" -oc pub2016.txt -ob pub2016.bib leconte.link.bib}}
@article{2016A&A...596A.112T,
author = {{Turbet}, M. and {Leconte}, J. and {Selsis}, F. and {Bolmont}, E. and
{Forget}, F. and {Ribas}, I. and {Raymond}, S.~N. and {Anglada-Escudé}, G.
},
title = {{The habitability of Proxima Centauri b. II. Possible climates and observability}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1608.06827},
primaryclass = {astro-ph.EP},
keywords = {stars: individual: Proxima Cen, planets and satellites: individual: Proxima Cen b, planets and satellites: atmospheres, planets and satellites: terrestrial planets, planets and satellites: detection, astrobiology},
year = 2016,
volume = 596,
eid = {A112},
pages = {A112},
abstract = {{Radial velocity monitoring has found the signature of a Msini =
1.3M$_{⊕}$ planet located within the habitable zone (HZ) of
Proxima Centauri. Despite a hotter past and an active host star, the
planet Proxima b could have retained enough volatiles to sustain surface
habitability. Here we use a 3D Global Climate Model (GCM) to simulate
the atmosphere and water cycle of Proxima b for its two likely rotation
modes (1:1 and 3:2 spin-orbit resonances), while varying the
unconstrained surface water inventory and atmospheric greenhouse effect.
Any low-obliquity, low-eccentricity planet within the HZ of its star
should be in one of the climate regimes discussed here. We find that a
broad range of atmospheric compositions allow surface liquid water. On a
tidally locked planet with sufficient surface water inventory, liquid
water is always present, at least in the substellar region. With a
non-synchronous rotation, this requires a minimum greenhouse warming (
10 mbar of CO$_{2}$ and 1 bar of N$_{2}$). If the planet is
dryer, 0.5 bar or 1.5 bars of CO$_{2}$ (for asynchronous or
synchronous rotation, respectively) suffice to prevent the trapping of
any arbitrary, small water inventory into polar or nightside ice caps.
We produce reflection and emission spectra and phase curves for the
simulated climates. We find that atmospheric characterization will be
possible via direct imaging with forthcoming large telescopes. The
angular separation of 7{$\lambda$}/D at 1 {$\mu$}m (with the E-ELT) and a
contrast of 10$^{-7}$ will enable high-resolution spectroscopy
and the search for molecular signatures, including H$_{2}$O,
O$_{2}$, and CO$_{2}$. The observation of thermal phase
curves can be attempted with the James Webb Space Telescope, thanks to a
contrast of 2 {\times} 10$^{-5}$ at 10 {$\mu$}m. Proxima b will also
be an exceptional target for future IR interferometers. Within a decade
it will be possible to image Proxima b and possibly determine whether
the surface of this exoplanet is habitable.
}},
doi = {10.1051/0004-6361/201629577},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...596A.112T},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.112T.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.112T.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.112T.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...596A.111R,
author = {{Ribas}, I. and {Bolmont}, E. and {Selsis}, F. and {Reiners}, A. and
{Leconte}, J. and {Raymond}, S.~N. and {Engle}, S.~G. and {Guinan}, E.~F. and
{Morin}, J. and {Turbet}, M. and {Forget}, F. and {Anglada-Escudé}, G.
},
title = {{The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1608.06813},
primaryclass = {astro-ph.EP},
keywords = {stars: individual: Proxima Cen, planets and satellites: individual: Proxima b, planets and satellites: atmospheres, X-rays: stars, planet-star interactions},
year = 2016,
volume = 596,
eid = {A111},
pages = {A111},
abstract = {{Proxima b is a planet with a minimum mass of 1.3M$_{⊕}$
orbiting within the habitable zone (HZ) of Proxima Centauri, a very
low-mass, active star and the Sun's closest neighbor. Here we
investigate a number of factors related to the potential habitability of
Proxima b and its ability to maintain liquid water on its surface. We
set the stage by estimating the current high-energy irradiance of the
planet and show that the planet currently receives 30 times more
extreme-UV radiation than Earth and 250 times more X-rays. We compute
the time evolution of the star's spectrum, which is essential for
modeling the flux received over Proxima b's lifetime. We also show that
Proxima b's obliquity is likely null and its spin is either synchronous
or in a 3:2 spin-orbit resonance, depending on the planet's eccentricity
and level of triaxiality. Next we consider the evolution of Proxima b's
water inventory. We use our spectral energy distribution to compute the
hydrogen loss from the planet with an improved energy-limited escape
formalism. Despite the high level of stellar activity we find that
Proxima b is likely to have lost less than an Earth ocean's worth of
hydrogen (EO$_{H}$) before it reached the HZ 100-200 Myr after its
formation. The largest uncertainty in our work is the initial water
budget, which is not constrained by planet formation models. We conclude
that Proxima b is a viable candidate habitable planet.
}},
doi = {10.1051/0004-6361/201629576},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...596A.111R},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.111R.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.111R.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.111R.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016Icar..277..196F,
author = {{Fouchet}, T. and {Greathouse}, T.~K. and {Spiga}, A. and {Fletcher}, L.~N. and
{Guerlet}, S. and {Leconte}, J. and {Orton}, G.~S.},
title = {{Stratospheric aftermath of the 2010 Storm on Saturn as observed by the TEXES instrument. I. Temperature structure}},
journal = {\icarus},
archiveprefix = {arXiv},
eprint = {1604.06479},
primaryclass = {astro-ph.EP},
keywords = {Saturn, atmosphere, Atmospheres, structure, Atmospheres, dynamics, Infrared observations},
year = 2016,
volume = 277,
pages = {196-214},
abstract = {{We report on spectroscopic observations of Saturn's stratosphere in July
2011 with the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted
on the NASA InfraRed Telescope Facility (IRTF). The observations,
targeting several lines of the CH$_{4}${$\nu$}$_{4}$ band and
the H$_{2}$ S(1) quadrupolar line, were designed to determine how
Saturn's stratospheric thermal structure was disturbed by the 2010 Great
White Spot. A study of Cassini Composite Infrared Spectrometer (CIRS)
spectra had already shown the presence of a large stratospheric
disturbance centered at a pressure of 2 hPa, nicknamed the beacon B0,
and a tail of warm air at lower pressures (Fletcher et al. [2012] Icarus
221, 560-586). Our observations confirm that the beacon B0 vertical
structure determined by CIRS, with a maximum temperature of 180 {\plusmn}
1 K at 2 hPa, is overlain by a temperature decrease up to the 0.2-hPa
pressure level. Our retrieved maximum temperature of 180 {\plusmn} 1 K is
colder than that derived by CIRS (200 {\plusmn} 1 K), a difference that
may be quantitatively explained by terrestrial atmospheric smearing. We
propose a scenario for the formation of the beacon based on the
saturation of gravity waves emitted by the GWS. Our observations also
reveal that the tail is a planet-encircling disturbance in Saturn's
upper stratosphere, oscillating between 0.2 and 0.02 hPa, showing a
distinct wavenumber-2 pattern. We propose that this pattern in the upper
stratosphere is either the signature of thermal tides generated by the
presence of the warm beacon in the mid-stratosphere, or the signature of
Rossby wave activity.
}},
doi = {10.1016/j.icarus.2016.04.030},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016Icar..277..196F},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016Icar..277..196F.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016Icar..277..196F.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016Icar..277..196F.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016ApJ...826..222Y,
author = {{Yang}, J. and {Leconte}, J. and {Wolf}, E.~T. and {Goldblatt}, C. and
{Feldl}, N. and {Merlis}, T. and {Wang}, Y. and {Koll}, D.~D.~B. and
{Ding}, F. and {Forget}, F. and {Abbot}, D.~S.},
title = {{Differences in Water Vapor Radiative Transfer among 1D Models Can Significantly Affect the Inner Edge of the Habitable Zone}},
journal = {\apj},
archiveprefix = {arXiv},
eprint = {1809.01397},
primaryclass = {astro-ph.EP},
keywords = {astrobiology, methods: numerical, planets and satellites: atmospheres, planets and satellites: general, planets and satellites: terrestrial planets, radiative transfer},
year = 2016,
volume = 826,
eid = {222},
pages = {222},
abstract = {{An accurate estimate of the inner edge of the habitable zone is critical
for determining which exoplanets are potentially habitable and for
designing future telescopes to observe them. Here, we explore
differences in estimating the inner edge among seven one-dimensional
radiative transfer models: two line-by-line codes (SMART and LBLRTM) as
well as five band codes (CAM3, CAM4\_Wolf, LMDG, SBDART, and AM2) that
are currently being used in global climate models. We compare radiative
fluxes and spectra in clear-sky conditions around G and M stars, with
fixed moist adiabatic profiles for surface temperatures from 250 to 360
K. We find that divergences among the models arise mainly from large
uncertainties in water vapor absorption in the window region (10 {$\mu$}m)
and in the region between 0.2 and 1.5 {$\mu$}m. Differences in outgoing
longwave radiation increase with surface temperature and reach 10-20 W
m$^{-2}$ differences in shortwave reach up to 60 W m$^{-2}$,
especially at the surface and in the troposphere, and are larger for an
M-dwarf spectrum than a solar spectrum. Differences between the two
line-by-line models are significant, although smaller than among the
band models. Our results imply that the uncertainty in estimating the
insolation threshold of the inner edge (the runaway greenhouse limit)
due only to clear-sky radiative transfer is {\ap}10\% of modern
Earth{\rsquo}s solar constant (I.e., {\ap}34 W m$^{-2}$ in global
mean) among band models and {\ap}3\% between the two line-by-line models.
These comparisons show that future work is needed that focuses on
improving water vapor absorption coefficients in both shortwave and
longwave, as well as on increasing the resolution of stellar spectra in
broadband models.
}},
doi = {10.3847/0004-637X/826/2/222},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...591A.144F,
author = {{Fromang}, S. and {Leconte}, J. and {Heng}, K.},
title = {{Shear-driven instabilities and shocks in the atmospheres of hot Jupiters}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1603.02794},
primaryclass = {astro-ph.EP},
keywords = {hydrodynamics, instabilities, shock waves, methods: numerical, planets and satellites: atmospheres},
year = 2016,
volume = 591,
eid = {A144},
pages = {A144},
abstract = {{Context. General circulation models of the atmosphere of hot Jupiters
have shown the existence of a supersonic eastward equatorial jet. These
results have been obtained using numerical schemes that filter out
vertically propagating sound waves and assume vertical hydrostatic
equilibrium, or were acquired with fully compressive codes that use
large dissipative coefficients.
Aims: We remove these two
limitations and investigate the effects of compressibility on the
atmospheric dynamics by solving the standard Euler equations.
Methods: This was done by means of a series of simulations performed in
the framework of the equatorial {$\beta$}-plane approximation using the
finite-volume shock-capturing code RAMSES.
Results: At low
resolution, we recover the classical results described in the
literature: we find a strong and steady supersonic equatorial jet of a
few km s$^{-1}$ that displays no signature of shocks. We next show
that the jet zonal velocity depends significantly on the grid meridional
resolution. When this resolution is fine enough to properly resolve the
jet, the latter is subject to a Kelvin-Helmholtz instability. The jet
zonal mean velocity displays regular oscillations with a typical
timescale of a few days and a significant amplitude of about 15\% of the
jet velocity. We also find compelling evidence for the development of a
vertical shear instability at pressure levels of a few bars. It seems to
be responsible for an increased downward kinetic energy flux that
significantly affects the temperature of the deep atmosphere and appears
to act as a form of drag on the equatorial jet. This instability also
creates velocity fluctuations that propagate upward and steepen into
weak shocks at pressure levels of a few mbars.
Conclusions: We
conclude that hot-Jupiter equatorial jets are potentially unstable to
both a barotropic Kelvin-Helmholtz instability and a vertical shear
instability. Upon confirmation using more realistic models, these two
instabilities could result in significant time variability of the
atmospheric winds, may provide a small-scale dissipation mechanism in
the flow, and might have consequences for the internal evolution of hot
Jupiters.
}},
doi = {10.1051/0004-6361/201527600},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...591A.144F},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.144F.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.144F.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.144F.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...591A.106B,
author = {{Bolmont}, E. and {Libert}, A.-S. and {Leconte}, J. and {Selsis}, F.
},
title = {{Habitability of planets on eccentric orbits: Limits of the mean flux approximation}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1604.06091},
primaryclass = {astro-ph.EP},
keywords = {planets and satellites: atmospheres, planets and satellites: terrestrial planets, methods: numerical},
year = 2016,
volume = 591,
eid = {A106},
pages = {A106},
abstract = {{Unlike the Earth, which has a small orbital eccentricity, some
exoplanets discovered in the insolation habitable zone (HZ) have high
orbital eccentricities (e.g., up to an eccentricity of \~{}0.97 for HD
20782 b). This raises the question of whether these planets have surface
conditions favorable to liquid water. In order to assess the
habitability of an eccentric planet, the mean flux approximation is
often used. It states that a planet on an eccentric orbit is called
habitable if it receives on average a flux compatible with the presence
of surface liquid water. However, because the planets experience
important insolation variations over one orbit and even spend some time
outside the HZ for high eccentricities, the question of their
habitability might not be as straightforward. We performed a set of
simulations using the global climate model LMDZ to explore the limits of
the mean flux approximation when varying the luminosity of the host star
and the eccentricity of the planet. We computed the climate of tidally
locked ocean covered planets with orbital eccentricity from 0 to 0.9
receiving a mean flux equal to Earth's. These planets are found around
stars of luminosity ranging from 1 L$_{&sun;}$ to
10$^{-4}$L$_{&sun;}$. We use a definition of habitability
based on the presence of surface liquid water, and find that most of the
planets considered can sustain surface liquid water on the dayside with
an ice cap on the nightside. However, for high eccentricity and high
luminosity, planets cannot sustain surface liquid water during the whole
orbital period. They completely freeze at apoastron and when approaching
periastron an ocean appears around the substellar point. We conclude
that the higher the eccentricity and the higher the luminosity of the
star, the less reliable the mean flux approximation.
}},
doi = {10.1051/0004-6361/201628073},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...591A.106B},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.106B.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.106B.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.106B.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...589A..52V,
author = {{von Paris}, P. and {Gratier}, P. and {Bordé}, P. and {Leconte}, J. and
{Selsis}, F.},
title = {{Inferring asymmetric limb cloudiness on exoplanets from transit light curves}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1602.04362},
primaryclass = {astro-ph.EP},
keywords = {techniques: photometric, planets and satellites: atmospheres, planets and satellites: individual: Kepler-7b, planets and satellites: individual: HAT-P-7b, planets and satellites: individual: HD 209458b},
year = 2016,
volume = 589,
eid = {A52},
pages = {A52},
abstract = {{Context. Clouds have been shown to be present in many exoplanetary
atmospheres. Cloud formation modeling predicts considerable
inhomogeneities of cloud cover, consistent with optical phase curve
observations. However, optical phase curves cannot resolve some existing
degeneracies between cloud location and cloud optical properties.
Aims: We present a conceptually simple technique for detecting
inhomogeneous cloud cover on exoplanets. Such an inhomogeneous cloud
cover produces an asymmetric primary transit of the planet in front of
the host star. Asymmetric transits produce characteristic residuals that
are different from standard symmetric models. Furthermore, bisector
spans can be used to determine asymmetries in the transit light curve.
Methods: We apply a model of asymmetric transits to the light
curves of HAT-P-7b, Kepler-7b, and HD 209458b and search for possible
cloud signatures. The nearly uninterrupted Kepler photometry is
particularly well suited for this method since it allows for a very high
time resolution.
Results: We do not find any statistically sound
cloud signature in the data of the considered planets. For HAT-P-7b, a
tentative detection of an asymmetric cloud cover is found, consistent
with analysis of the optical phase curve. Based on Bayesian probability
arguments, a symmetric model with an offset in the transit ephemeris is
still the most viable model. This work demonstrates that for suitable
targets, namely low-gravity planets around bright stars, the method can
be used to constrain cloud cover characteristics and is thus a helpful
additional tool for the study of exoplanetary atmospheres.
}},
doi = {10.1051/0004-6361/201527894},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...589A..52V},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...589A..52V.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...589A..52V.pdf},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...589A..52V.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}