Model Calculations for Io's Atmosphere at Eastern and Western Elongations

Wong, M. C.; Smyth, W. H.

doi:10.1006/icar.2000.6362

Cited by 69 publications

(72 citation statements)

References 34 publications

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“…The atmosphere is supported by a combination of direct volcanic supply and frost sublimation (Fanale et al 1982, Ingersoll et al 1989, Moreno et al 1991, Wong and Smyth 2000, Zhang et al 2003. The relative roles of the volcanos and the surface frost in directly supporting the atmosphere depend on the frost temperature and the volcanic supply rate, and have not yet been determined.…”

Section: Introductionmentioning

confidence: 99%

“…The arguments for the dominance of one or the other mechanism are considered later, in the discussion section. The question is important because a sublimation-supported atmosphere is likely to collapse at night and during Jupiter eclipse due to frost cooling, dramatically changing the interaction of Io with the magnetosphere (Wong and Smyth 2000), and will have a different local distribution, being concentrated more around SO 2 frost deposits than active volcanic plumes. …”

Section: Introductionmentioning

confidence: 99%

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Mid-infrared detection of large longitudinal asymmetries in Io's SO atmosphere

Spencer¹,

Lellouch²,

Richter³

et al. 2005

Icarus

103

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We have observed about 16 absorption lines of the ν 2 SO 2 vibrational band on Io, in disk-integrated 19 µm spectra taken with the TEXES high spectral resolution mid-infrared spectrograph at the NASA Infrared Telescope Facility in November 2001, December 2002, and January 2004 These are the first ground-based infrared observations of Io's sunlit atmosphere, and provide a new window on the atmosphere that allows better longitudinal and temporal monitoring than previous techniques. Dramatic variations in band strength with longitude are seen that are stable over at least a 2 year period. The depth of the strongest feature, a blend of lines centered at 530.42 cm -1 , varies from about 7% near longitude 180 to about 1% near longitude 315 W, as measured at a spectral resolution of 57,000. Interpretation of the spectra requires modeling of surface temperatures and atmospheric density across Io's disk, and the variation in non-LTE ν 2 vibrational temperature with altitude, and depends on the assumed atmospheric and surface temperature structure. About half of Io's 19µm radiation comes from the sun-heated surface, and half from volcanic hot spots with temperatures primarily between 150 and 200 K, which occupy about 8% of the surface. The observations are thus weighted towards the atmosphere over these lowtemperature hot spots. If we assume that the atmosphere over the hot spots is representative of the atmosphere elsewhere, and that the atmospheric density is a function of latitude, the most plausible interpretation of the data is that the equatorial atmospheric column density varies from about 1.5 x 10 17 cm -2 near longitude 180 W to about 1.5 x 10 16 cm -2 near longitude 300 W, roughly consistent with HST UV spectroscopy and Lyman-α imaging. The inferred atmospheric kinetic temperature is less than about 150 K, at least on the anti-Jupiter hemisphere where the bands are strongest, somewhat colder than inferred from HST UV spectroscopy and millimeter-wavelength spectroscopy. This longitudinal variability in atmospheric density correlates with the longitudinal variability in the abundance of optically thick, near-UV bright SO 2 frost. However it is not clear whether the correlation results from volcanic control (regions of large frost abundance result from greater condensation of atmospheric gases supported by more vigorous volcanic activity in these regions) or sublimation control (regions of large frost abundance produce a more extensive atmosphere due to more extensive sublimation). Comparison of data taken in 2001, 2002, and 2004 shows that with the possible exception of longitudes near 180 W between 2001 and 2002, Io's atmospheric density does not appear to decrease as Io recedes from the sun, as would be expected if the atmosphere were supported by the sublimation of surface frost, suggesting that the atmosphere is dominantly supported by direct volcanic supply rather than by frost sublimation. However, other evidence such as the smooth variation in atmospheric abundance with latitude, and atmospheric ch...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mid-infrared detection of large longitudinal asymmetries in Io's SO atmosphere

Spencer¹,

Lellouch²,

Richter³

et al. 2005

Icarus

103

View full text Add to dashboard Cite

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“…The ratio for sodium is smaller due to the shorter lifetime. By comparison the ratio at Io is 3 for O and 1 for S (Wong and Smyth, 2000;Smyth and Marconi, 2003), and the total Europa neutral cloud content, maximum column density, and maximum density exceed that for the total Io neutral cloud (Fig. 9) by a factor of 3.…”

Section: Neutral Clouds and Extended Atmospherementioning

confidence: 87%

Composition and Detection of Europa’s Sputter-induced Atmosphere

Johnson¹,

Burger²,

Cassidy³

et al.

Europa

118

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An intense flux of ions and electrons from the jovian magnetosphere both alters and erodes Europa's surface, producing a tenuous atmosphere. This chapter discusses the physical processes that create and remove the atmosphere, such as ion erosion (sputtering), radiation-induced chemical alteration of the surface (radiolysis), and atmospheric loss processes such as ionization and pickup. Special emphasis is placed on ongoing modeling efforts to connect atmospheric properties to surface composition. Models are at present constrained by a small number of observations, but a future mission to Europa has the potential to detect even trace atmospheric species.

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“…The tidal heating generated due to Io's orbital eccentricity produces at its surface hundreds of volcanic spots and extensive lava flows. Three main mechanisms for generating an atmosphere on Io are proposed: frost sublimation, surface sputtering, and active volcanism (e.g., Chrisey et al 1988;Wong & Smyth 2000;Bagenal & Delamere 2011). During a major eruption, lava flows tens or even hundreds of kilometers long can be produced, which consist mainly of basalt silicate lavas with either mafic or ultramafic Mg-rich compositions.…”

Section: Io's Volcanic Activitymentioning

confidence: 99%

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

Kislyakova

Pilat-Lohinger

Funk

et al. 2016

Mon. Not. R. Astron. Soc.

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We suggest an additional possible plasma source to explain part of the phenomena observed for the transiting hot Jupiters WASP-12b and HD 189733b in their ultraviolet (UV) light curves. In the proposed scenario, material outgasses from the molten surface of Trojan satellites on tadpole orbits near the Lagrange points L 4 and L 5 . We show that the temperature at the orbital location of WASP-12b is high enough to melt the surface of rocky bodies and to form shallow lava oceans on them. In case of WASP12b, this leads to the release of elements such as Mg and Ca, which are expected to surround the system. The predicted Mg and Ca outgassing rates from two Io-sized WASP-12b Trojans are ≈ 2.2 × 10 27 s −1 and ≈ 2.2 × 10 26 s −1 , respectively. Trojan outgassing can lead to the apparent lack of emission in Mgii h&k and Caii H&K line cores of WASP-12. For HD 189733b, the mechanism is only marginally possible due to the lower temperature. This may be one of the reasons that couldn't explain the early ingress of HD 189733b observed in the far-UV (FUV) Cii doublet due to absence of carbon within elements outgassed by molten lava. We investigate the long-term stability region of WASP-12b and HD 189733b in case of planar and inclined motion of these satellites and show that unlike the classical exomoons orbiting the planet, Io-sized Trojans can be stable for the whole systems life time.

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Model Calculations for Io's Atmosphere at Eastern and Western Elongations

Cited by 69 publications

References 34 publications

Mid-infrared detection of large longitudinal asymmetries in Io's SO atmosphere

Mid-infrared detection of large longitudinal asymmetries in Io's SO atmosphere

Composition and Detection of Europa’s Sputter-induced Atmosphere

On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source

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