Transit Signatures of Inhomogeneous Clouds on Hot Jupiters: Insights From Microphysical Cloud Modeling. (arXiv:1910.07527v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Powell_D/0/1/0/all/0/1">Diana Powell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Louden_T/0/1/0/all/0/1">Tom Louden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kreidberg_L/0/1/0/all/0/1">Laura Kreidberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_X/0/1/0/all/0/1">Xi Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_P/0/1/0/all/0/1">Peter Gao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parmentier_V/0/1/0/all/0/1">Vivien Parmentier</a>
We determine the observability in transmission of inhomogeneous cloud cover
on the limbs of hot Jupiters through post processing a general circulation
model to include cloud distributions computed using a cloud microphysics model.
We find that both the east and west limb often form clouds, but that the
different properties of these clouds enhances the limb to limb differences
compared to the clear case. Using JWST it should be possible to detect the
presence of cloud inhomogeneities by comparing the shape of the transit
lightcurve at multiple wavelengths because inhomogeneous clouds impart a
characteristic, wavelength dependent signature. This method is statistically
robust even with limited wavelength coverage, uncertainty on limb darkening
coefficients, and imprecise transit times. We predict that the short wavelength
slope varies strongly with temperature. The hot limb of the hottest planets
form higher altitude clouds composed of smaller particles leading to a strong
rayleigh slope. The near infrared spectral features of clouds are almost always
detectable, even when no spectral slope is visible in the optical. In some of
our models a spectral window between 5 and 9 microns can be used to probe
through the clouds and detect chemical spectral features. Our cloud particle
size distributions are not log-normal and differ from species to species. Using
the area or mass weighted particle size significantly alters the relative
strength of the cloud spectral features compared to using the predicted size
distribution. Finally, the cloud content of a given planet is sensitive to a
species’ desorption energy and contact angle, two parameters that could be
constrained experimentally in the future.
We determine the observability in transmission of inhomogeneous cloud cover
on the limbs of hot Jupiters through post processing a general circulation
model to include cloud distributions computed using a cloud microphysics model.
We find that both the east and west limb often form clouds, but that the
different properties of these clouds enhances the limb to limb differences
compared to the clear case. Using JWST it should be possible to detect the
presence of cloud inhomogeneities by comparing the shape of the transit
lightcurve at multiple wavelengths because inhomogeneous clouds impart a
characteristic, wavelength dependent signature. This method is statistically
robust even with limited wavelength coverage, uncertainty on limb darkening
coefficients, and imprecise transit times. We predict that the short wavelength
slope varies strongly with temperature. The hot limb of the hottest planets
form higher altitude clouds composed of smaller particles leading to a strong
rayleigh slope. The near infrared spectral features of clouds are almost always
detectable, even when no spectral slope is visible in the optical. In some of
our models a spectral window between 5 and 9 microns can be used to probe
through the clouds and detect chemical spectral features. Our cloud particle
size distributions are not log-normal and differ from species to species. Using
the area or mass weighted particle size significantly alters the relative
strength of the cloud spectral features compared to using the predicted size
distribution. Finally, the cloud content of a given planet is sensitive to a
species’ desorption energy and contact angle, two parameters that could be
constrained experimentally in the future.
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