Estimates of the bolometric albedos and radiation balance of Uranus and Neptune

Pollack, James B.; Rages, K.; Baines, K. H.; Bergstralh, J. T.; Wenkert, Daniel; Danielson, G. E.

doi:10.1016/0019-1035(86)90147-8

Cited by 81 publications

(80 citation statements)

References 27 publications

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“…Opacity sources considered when calculating the geometric albedo spectrum include molecular absorption, as previously mentioned (including collision-induced absorption of H 2 -H, H 2 -H 2 , H 2 -He, and H 2 -CH 4 ), as well as Rayleigh scattering (Cahoy et al 2010) and Raman scattering (Pollack et al 1986). The optical depths, single scattering albedos, and asymmetry parameters calculated by the cloud model are fed as input parameters into a double Henyey-Greenstein phase function to account for the opacity and anisotropic scattering of the condensate clouds and the sulfur haze.…”

Section: Geometric Albedo Modelmentioning

confidence: 99%

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Gao

Marley

Zahnle

et al. 2017

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Recent work has shown that sulfur hazes may arise in the atmospheres of some giant exoplanets, due to the photolysis of H 2 S. We investigate the impact such a haze would have on an exoplanet's geometric albedo spectrum and how it may affect the direct imaging results of the Wide Field Infrared Survey Telescope (WFIRST), a planned NASA space telescope. For temperate (250 K<T eq <700 K) Jupiter-mass planets, photochemical destruction of H 2 S results in the production of ∼1 ppmv of S 8 between 100 and 0.1 mbar, which, if cool enough, will condense to form a haze. Nominal haze masses are found to drastically alter a planet's geometric albedo spectrum: whereas a clear atmosphere is dark at wavelengths between 0.5 and 1 μm, due to molecular absorption, the addition of a sulfur haze boosts the albedo there to ∼0.7, due to scattering. Strong absorption by the haze shortward of 0.4 μm results in albedos <0.1, in contrast to the high albedos produced by Rayleigh scattering in a clear atmosphere. As a result, the color of the planet shifts from blue to orange. The existence of a sulfur haze masks the molecular signatures of methane and water, thereby complicating the characterization of atmospheric composition. Detection of such a haze by WFIRST is possible, though discriminating between a sulfur haze and any other highly reflective, high-altitude scatterer will require observations shortward of 0.4 μm, which is currently beyond WFIRST's design.

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Section: Geometric Albedo Modelmentioning

confidence: 99%

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Gao

Marley

Zahnle

et al. 2017

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“…We also show a few examples of Solar System moons, where we adopted 0.343 for Jupiter's bond albedo (Hanel et al, 1981), 0.342 for Saturn (Hanel et al, 1983), 0.32 for Uranus (Neff et al, 1985;Pollack et al, 1986;Pearl et al, 1990), 0.29 for Neptune (Neff et al, 1985;Pollack et al, 1986;Pearl and Conrath, 1991), and 0.3 for Earth. Flux contours are not directly applicable to the indicated moons because the host planets Jupiter, Saturn, Uranus, and Neptune do not orbit the Sun at 1 AU, as assumed for our prototype exomoon system 7 .…”

Section: Heller and Barnesmentioning

confidence: 99%

Exomoon Habitability Constrained by Illumination and Tidal Heating

2013

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The detection of moons orbiting extrasolar planets (''exomoons'') has now become feasible. Once they are discovered in the circumstellar habitable zone, questions about their habitability will emerge. Exomoons are likely to be tidally locked to their planet and hence experience days much shorter than their orbital period around the star and have seasons, all of which works in favor of habitability. These satellites can receive more illumination per area than their host planets, as the planet reflects stellar light and emits thermal photons. On the contrary, eclipses can significantly alter local climates on exomoons by reducing stellar illumination. In addition to radiative heating, tidal heating can be very large on exomoons, possibly even large enough for sterilization. We identify combinations of physical and orbital parameters for which radiative and tidal heating are strong enough to trigger a runaway greenhouse. By analogy with the circumstellar habitable zone, these constraints define a circumplanetary ''habitable edge.'' We apply our model to hypothetical moons around the recently discovered exoplanet Kepler-22b and the giant planet candidate KOI211.01 and describe, for the first time, the orbits of habitable exomoons. If either planet hosted a satellite at a distance greater than 10 planetary radii, then this could indicate the presence of a habitable moon.

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“…It was found that large planets -Jupiter, Saturn, Neptune, Uranus and Earth not only get their energy from the Sun, but also have their own internal energy sources [Hanel et al, 1981[Hanel et al, , 1983Pollac et al, 1986Pollac et al, , 1993.…”

Section: Source Of the Internal Energy Of The Earthmentioning

confidence: 99%

“…In this paper we analyzed the data shown in [Hanel et al, 1981[Hanel et al, , 1983Pollac et al, 1986Pollac et al, , 1993. Figure 4a and Figure 4b shows the mass-luminosity relationship for: a) the following planets: Earth, Uranus, Neptune, Saturn, Jupiter; b) the same planets and the Sun.…”

Section: Source Of the Internal Energy Of The Earthmentioning

confidence: 99%

Neutrons of terrestrial origin and the endogenous activity of the Earth

Shestopalov¹

2016

Russ. J. Earth Sci.

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As a result of ground measurements of a) thermal and fast neutrons, carried out at the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Moscow; b) thermal neutrons, carried out at the Karymshina Complex Geophysical Observatory, Kamchatka Branch, Geophysical Survey, Russian Academy of Sciences, near Petropavlovsk-Kamchatsky in 2010-2012, neutron fluxes were registered, related to earthquakes in Chile, Japan, Indonesia. The magnitude of these earthquakes was = 8.6 − 9. Fluxes of neutrons were also registered during the volcanic eruption in Iceland in 2010. In 2013-2015 bursts of neutron fluxes were registered, not only by the instrumental complex with helium counters, i.e. with an energy of several MeV, but also by neutron monitors with threshold energy of 20-30 MeV. We can assume that the emergence of neutrons on the surface of the Earth is related to nuclear reactions in the Earth's interior, generating a variety of particles with high penetrating capacity.KEYWORDS: Thermal and fast neutrons; generation of neutrons; nuclear reactions; neutron monitors; seismicity and volcanism of the Earth.

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Estimates of the bolometric albedos and radiation balance of Uranus and Neptune

Cited by 81 publications

References 27 publications

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Exomoon Habitability Constrained by Illumination and Tidal Heating

Neutrons of terrestrial origin and the endogenous activity of the Earth

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