The spectrum of Jupiter's Great Red Spot: The case for ammonium hydrosulfide (NH4SH)

Loeffler, M. J.; Hudson, R. L.; Chanover, N. J.; Simon-Miller, A. A.

doi:10.1016/j.icarus.2016.02.010

Cited by 26 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hazes in the upper troposphere near 200 mbars are bright at 0.89 µm and at 2.2 µm and dark in the ultraviolet. Chromophores mixed into the haze absorb strongly in both ultraviolet and blue wavelengths giving the GRS its red color (see Wong et al (2011);Loeffler et al (2016)). Ammonia and ammonium hydrosulfide clouds can be probed by reflected sunlight using filters in the optical and near-infrared.…”

Section: Observationsmentioning

confidence: 99%

The Gas Composition and Deep Cloud Structure of Jupiter's Great Red Spot

Bjoraker¹,

Wong

Pater

et al. 2018

View full text Add to dashboard Cite

We have obtained high-resolution spectra of Jupiter's Great Red Spot (GRS) between 4.6 and 5.4 µm using telescopes on Mauna Kea in order to derive gas abundances and to constrain its cloud structure between 0.5 and 5 bars. We used line profiles of deuterated methane (CH 3 D) at 4.66 µm to infer the presence of an opaque cloud at 5±1 bars. From thermochemical models this is almost certainly a water cloud. We also used the strength of Fraunhofer lines in the GRS to obtain the ratio of reflected sunlight to thermal emission. The level of the reflecting layer was constrained to be at 570±30 mbars based on fitting strong NH 3 lines at 5.32 µm. We identify this layer as an ammonia cloud based on the temperature where gaseous NH 3 condenses. We found evidence for a strongly absorbing, but not totally opaque, cloud layer at pressures deeper than 1.3 bars by combining Cassini/CIRS spectra of the GRS at 7.18 µm with ground-based spectra at 5 µm. This is consistent with the predicted level of an NH 4 SH cloud. We also constrained the vertical profile of H 2 O and NH 3 . The GRS spectrum is matched by a saturated H 2 O profile above an opaque water cloud at 5 bars. The pressure of the water cloud constrains Jupiter's O/H ratio to be at least 1.1 times solar. The NH 3 mole fraction is 200±50 ppm for pressures between 0.7 and 5 bars. Its abundance is 40 ppm at the estimated pressure of the reflecting layer. We obtained 0.8±0.2 ppm for PH 3 , a factor of 2 higher than in the warm collar surrounding the GRS. We detected all 5 naturally occurring isotopes of germanium in GeH 4 in the Great Red Spot. We obtained an average value of 0.35±0.05 ppb for GeH 4 . Finally, we measured 0.8±0.2 ppb for CO in the deep atmosphere.

show abstract

Section: Observationsmentioning

confidence: 99%

The Gas Composition and Deep Cloud Structure of Jupiter's Great Red Spot

Bjoraker¹,

Wong

Pater

et al. 2018

View full text Add to dashboard Cite

show abstract

“…At temperatures below ∼200 K NH 3 condenses and reacts with H 2 S to form NH 4 SH (Atreya et al 1999;Loeffler et al 2016), whereas above ∼1500 K (at P<1 bar) it dissociates into SH and S (Visscher et al 2006). The stability of H 2 S is disrupted by disequilibrium processes, however, as upward transport of H 2 S to the tropopause by turbulent mixing and advection results in its destruction by photolysis and reactions with atomic H released from photolysis of CH 4 , NH 3 , and H 2 O (Zahnle et al 2016):…”

Section: Sulfur In Giant Exoplanetsmentioning

confidence: 99%

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

Gao

Marley

Zahnle

et al. 2017

View full text Add to dashboard Cite

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.

show abstract

“…The dashed line displays the tholin index ofKhare et al (1993) multiplied by a factor of ten. For reference, panel A displays theLoeffler et al (2016) measurement of reflectivity of NH 4 SH irradiated at a temperature of 120 K and warmed to a temperature of 190 K (dashed) and 200 K (solid). The y-axis scale in A is inverted so that increasing absorption is in the same sense (upward) as the refractive index plots in panel B.…”

mentioning

confidence: 99%

A possibly universal red chromophore for modeling color variations on Jupiter

Sromovsky

Baines

Fry

et al. 2017

Icarus

View full text Add to dashboard Cite

A new laboratory-generated chemical compound made from photodissociated ammonia (NH 3 ) molecules reacting with acetylene (C 2 H 2 ) was suggested as a possible coloring agent for Jupiter's Great Red Spot (GRS) by Carlson et al. (2016, Icarus 274, 106-115). Baines et al. (2016, Icarus, submitted) showed that the GRS spectrum measured by the visual channels of the Cassini VIMS instrument in 2000 could be accurately fit by a cloud model in which the chromophore appeared as a physically thin layer of small particles immediately above the main cloud layer of the GRS. Here we show that the same chromophore and same layer location can also provide close matches to the short wave spectra of many other cloud features on Jupiter, suggesting this material may be a nearly universal chromophore that could explain the various degrees of red coloration on Jupiter. This is a robust conclusion, even for 12% changes in VIMS calibration and large uncertainties in the refractive index of the main cloud layer due to uncertain fractions of NH 4 SH and NH 3 in its cloud particles. The chromophore layer can account for color variations among north and south equatorial belts, equatorial zone, and the Great Red Spot, by varying particle size from 0.12 µm to 0.29 µm and 1-µm optical depth from 0.06 to 0.76. The total mass of the chromophore layer is much less variable, ranging from 18 to 30 µg/cm 2 , except in the equatorial zone, where it is only 10-13 µg/cm 2 . We also found a depression of the ammonia volume mixing ratio in the two belt regions, which averaged 0.4-0.5 ×10 −4 immediately below the ammonia condensation level, while the other regions averaged twice that value.

show abstract

The spectrum of Jupiter's Great Red Spot: The case for ammonium hydrosulfide (NH4SH)

Cited by 26 publications

References 27 publications

The Gas Composition and Deep Cloud Structure of Jupiter's Great Red Spot

The Gas Composition and Deep Cloud Structure of Jupiter's Great Red Spot

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

A possibly universal red chromophore for modeling color variations on Jupiter

Contact Info

Product

Resources

About