The upper Jovian atmosphere aerosol content determined from a satellite eclipse observation

Smith, D. W.; Greene, T. F.; Shorthill, R. W.

doi:10.1016/0019-1035(77)90089-6

Cited by 32 publications

(7 citation statements)

References 30 publications

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“…Consequently, the data used in the present analysis have not been corrected for this effect. In the pressure regime of the present observations (P •< 10/•bar), the effect of haze--such as seen at the millibar or higher pressures [Cook et al, 1979;Smith et al, 1977]--is unimportant.…”

Section: Introductioncontrasting

confidence: 49%

Composition and thermal profiles of the Jovian upper atmosphere determined by the Voyager Ultraviolet Stellar Occultation Experiment

Atreya²,

et al. 1981

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Occultation of the star Regulus—α Leo—by the Jovian atmosphere was monitored by the Voyager 2 spacecraft on July 9, 1979. The absorption recorded in the 910–1200 Å range was caused primarily by the H2‐Lyman and Werner bands. These data provide the first complete measurements of atmospheric density and temperature profiles between 330 and 830 km above the ammonia cloud tops. The molecular hydrogen density at 380 km is found to be 3−1+4 × 1013 cm−3, where the atmospheric temperature is 200±50 K. The thermal gradient above 830 km altitude is found to be approximately 1 K km−1 to reconcile the stellar occultation data with the Voyager 1 solar occultation data for the exosphere. Both experiments were performed in the equatorial region. The observed temperature gradient in the upper atmosphere rules out inertia gravity wave propagation as the primary heating mechanism; the heating must be caused by one or many of a host of other potential sources such as magnetospheric electrons (soft or hard), Joule heating and even solar extreme ultraviolet radiation. The data do not present a strong argument in favor of an earthlike mesopause on Jupiter. The absorption in the 1250–1600 Å range yields volume mixing ratios of methane and ethane of 2.5−2+3 × 10−5 and 2.5−1.5+2.0 × 10−6, respectively, at a height of 325 km above the ammonia cloud tops. An upper limit of 2.5 × 10−6 for the mixing ratio of acetylene has been found at the altitude of 300 km. The Voyager infrared data yield mixing ratios of these hydrocarbons deeper in the stratosphere. A study of the density profiles of the hydrocarbons deduced from the stellar occultation data yields a value of the eddy diffusion coefficient at the homopause to be 1.4−0.7+0.8 × 106 cm² s−1 in the equatorial region which is consistent with the value deduced from the hydrogen Lyman alpha and helium 584 Å emission data. Detailed aeronomical implications of the results are discussed elsewhere (Atreya et al., 1981).

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Section: Introductioncontrasting

confidence: 49%

Composition and thermal profiles of the Jovian upper atmosphere determined by the Voyager Ultraviolet Stellar Occultation Experiment

Atreya²,

et al. 1981

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“…The ubiquity of the cloud cover on Venus makes this reduction a global feature. Discovery of frequent lightning discharges (Russell et al 2007 and references therein) in the atmosphere show the active electrical processes in Venus. The presence of lightning implies that the charge separation mechanisms operate at a rate sufficient to overcome the dissipation of the separated charge by atmospheric conduction.…”

Section: Electrical Conductivitymentioning

confidence: 98%

Profiles of Ion and Aerosol Interactions in Planetary Atmospheres

2008

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In planetary atmospheres the nature of the aerosols varies, as does the relative importance of different sources of ion production. The nature of the aerosol and ion production is briefly reviewed here for the atmospheres of Venus, Mars, Jupiter and Titan using the concepts established for the terrestrial atmosphere. Interactions between the ions formed and aerosols present cause (1) charge exchange, which can lead to substantial aerosol charge and (2) ion removal. Consequences of (1) are that (a) charged aerosol are more effectively removed by conducting liquid droplets than uncharged aerosol and (b) particle-particle coagulation rates are modified, influencing particle residence times in the relevant atmosphere. Consequences of (2) are that ions are removed in regions with abundant aerosol, which may preclude charge flow in an atmosphere, such as that associated with an atmospheric electrical circuit. In general, charge should be included in microphysical modeling of the properties of planetary aerosols.

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“…For example, observed brightness variances of Ganymede and Callisto shown in Figure 2 might be explained by the variance of the haze abundance in the Jovian atmosphere. Similar studies were conducted to investigate the composition of the Jovian atmosphere using Galilean satellites' eclipses (Smith et al 1977;Greene et al 1980;Smith 1980;. However, these previous works were based on ingress and egress eclipse light curves that probed reflected/refracted sunlight through regions of the Jovian upper atmosphere (specifically, the bottom of the Jovian stratosphere at pressures of several hundred mbars).…”

Section: Forward-scattered Sunlight At Jovian Upper Atmospherementioning

confidence: 99%

“…The historic first measurement of the speed of light was achieved by observations of eclipses of Galilean satellites (Römer 1676), and this kind of observation has recently been used to obtain accurate astrometric data with great precision (Emelyanov & Gilbert 2006;Emelyanov 2009;Mallama et al 2010;Emelyanov et al 2011). The Jovian upper atmosphere was previously investigated through satellite eclipse events (Smith et al 1977;Greene et al 1980;Smith 1980;, which allowed studies of the Jovian atmosphere through Earth-based astronomical observations as opposed to in situ studies by spacecraft missions to Jupiter. These eclipse studies were based on the shape of the ingress and egress light curves (Mallama 1991(Mallama , 1992, since no emission was expected to be detectable during the eclipse itself.…”

Section: Introductionmentioning

confidence: 99%

Near-Infrared Brightness of the Galilean Satellites Eclipsed in Jovian Shadow: A New Technique to Investigate Jovian Upper Atmosphere

Tsumura

Arimatsu

Egami

et al. 2014

ApJ

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Based on observations from the Hubble Space Telescope and the Subaru Telescope, we have discovered that Europa, Ganymede, and Callisto are bright around 1.5 μm even when not directly lit by sunlight. The observations were conducted with non-sidereal tracking on Jupiter outside of the field of view to reduce the stray light subtraction uncertainty due to the close proximity of Jupiter. Their eclipsed luminosity was 10 −6 -10 −7 of their uneclipsed brightness, which is low enough that this phenomenon has been undiscovered until now. In addition, Europa in eclipse was <1/10 of the others at 1.5 μm, a potential clue to the origin of the source of luminosity. Likewise, Ganymede observations were attempted at 3.6 μm by the Spitzer Space Telescope, but it was not detected, suggesting a significant wavelength dependence. It is still unknown why they are luminous even when in the Jovian shadow, but forward-scattered sunlight by hazes in the Jovian upper atmosphere is proposed as the most plausible candidate. If this is the case, observations of these Galilean satellites while eclipsed by the Jovian shadow provide us with a new technique to investigate the Jovian atmospheric composition. Investigating the transmission spectrum of Jupiter by this method is important for investigating the atmosphere of extrasolar giant planets by transit spectroscopy.

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The upper Jovian atmosphere aerosol content determined from a satellite eclipse observation

Cited by 32 publications

References 30 publications

Composition and thermal profiles of the Jovian upper atmosphere determined by the Voyager Ultraviolet Stellar Occultation Experiment

Composition and thermal profiles of the Jovian upper atmosphere determined by the Voyager Ultraviolet Stellar Occultation Experiment

Profiles of Ion and Aerosol Interactions in Planetary Atmospheres

Near-Infrared Brightness of the Galilean Satellites Eclipsed in Jovian Shadow: A New Technique to Investigate Jovian Upper Atmosphere

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