Io's volcanic control of Jupiter's extended neutral clouds
TL;DR: In this article, dramatic changes in the brightness and shape of Jupiter's extended sodium nebula are found to be correlated with the infrared emission brightness of Io, and they conclude that silicate volcanism on Io controls both the rate and the means by which sodium escapes from Io's atmosphere.
About: This article is published in Icarus.The article was published on 2004-08-01. It has received 42 citations till now. The article focuses on the topics: Atmospheric escape & Population.
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29 citations
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...The plasma density and temperature in the IPT are known to vary over time due to the change in volcanic activity on Io [Brown and Bouchez, 1997; Delamere and Bagenal, 2003; Nozawa et al., 2004; Steffl et al., 2004a; Mendillo et al., 2004; Yoneda et al., 2010, 2015]....
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TL;DR: In this paper, a new four-dimensional (three spatial and local time) empirical model for the Io plasma torus is presented that includes several System III longitude asymmetries and a dawn-dusk electric field with variable direction and magnitude.
Abstract: [1] A new four-dimensional (three spatial and local time) empirical model for the Io plasma torus is presented that includes several System III longitude asymmetries and a dawn-dusk electric field with variable direction and magnitude. The model is used to analyze and compare observations for the peak density structure of the plasma torus acquired at the 1979 Voyager 1, the 1991 ground-based, and the 1995 Galileo J0 epochs. The mean magnitude of the dawn-dusk electric field is determined to be much smaller at the 1991 ground-based epoch than at the Voyager 1 and Galileo J0 epochs. A consistent understanding of the radial structure for the density peaks in the plasma torus may then be achieved for these epochs if the dawn-dusk electric field departs by ∼20° from the true dawn-dusk direction and if account is taken of absolute density changes. The ratio of the electron density in the inner and outer plasma torus varies significantly for the three epochs and indicates different temporal evolutions in the balance of the plasma torus production and loss processes. The undisturbed electron density at Io's position in the plasma torus is calculated and has significantly different values at the three epochs; it is shown for each epoch to undergo large variations as Io changes its location in heliocentric phase angle and System III longitude. These large variations provide a wide variety of changing upstream plasma conditions for Io's atmospheric formation, local aurora and distant footprint emissions, and electrodynamic interaction.
28 citations
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...The new model provides a description for the basic structure of the plasma torus, which in addition is known to exhibit short‐time erratic fluctuations, temporal localized density enhancements, and longer‐term variability [e.g., Brown, 1995; Oliversen et al., 2001; Nozawa et al., 2004; Mendillo et al., 2004; Steffl et al., 2006; Yoneda et al., 2010]....
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TL;DR: In this paper, the spectral search for expected yet undetected molecular species (KCl, SiO, S2O) and isotopes ((SO2)-S-34) was focused on the spectrum of a potentially line-rich spectral window around 345 GHz.
Abstract: The composition of Io's tenuous atmosphere is poorly constrained. Only the major species SO2 and a handful of minor species have been positively identified, but a variety of other molecular species should be present, based on thermochemical equilibrium models of volcanic gas chemistry and the composition of Io's environment. This paper focuses on the spectral search for expected yet undetected molecular species (KCl, SiO, S2O) and isotopes ((SO2)-S-34). We analyze a disk-averaged spectrum of a potentially line-rich spectral window around 345 GHz, obtained in 2010 at the APEX 12 m antenna. Using different models assuming either extended atmospheric distributions or a purely volcanically sustained atmosphere, we tentatively measure the KCl relative abundance with respect to SO2 and derive a range of 4 x 10(-4)-8 x 10(-3). We do not detect SiO or S2O and present new upper limits on their abundances. We also present the first measurement of the S-34/S-32 isotopic ratio in gas phase on Io, which appears to be twice as high as the Earth and interstellar medium reference values. Strong lines of SO2 and SO are also analyzed to check for longitudinal variations of column density and relative abundance. Our models show that, based on their predicted relative abundance with respect to SO2 in volcanic plumes, both the tentative KCl detection and SiO upper limit are compatible with a purely volcanic origin for these species.
28 citations
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...Mendillo et al. (2004) measured the Na escape rate during volcanically active periods to be between 1.8-5.6×109 Na atoms/s.cm−2....
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TL;DR: In this paper, the authors used the Hisaki satellite to investigate the time variation of atomic oxygen emission around Io during the same period of 30 days as the observed sodium brightness, and found that the duration of the atomic oxygen brightness increases from a volcanically quiet level to a maximum level during a volcanic event.
27 citations
TL;DR: In this paper, the authors used a wide field filter imager to obtain ground-based optical observations of D 1 and D 2 line emissions from Jupiter's sodium nebula, which extend over several hundreds of jovian radii, from May 19 to June 21, 2007.
26 citations
References
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01 Jan 2004
TL;DR: In this paper, the authors present a model for the formation and evolution of the inner and outer clouds of the Jovian satellite system, including the formation of the outer clouds.
Abstract: Preface 1. Introduction F. Bagenal, T. E. Dowling and W. B. McKinnon 2. The origin of Jupiter J. I. Lunine, A. Corandini, D. Gautier, T. C. Owen and G. Wuchterl 3. The interior of Jupiter T. Guillot, D. J. Stevenson, W. B. Hubbard and D. Saumon 4. The composition of the atmosphere of Jupiter F. W. Taylor, S. K. Atreya, Th. Encrenaz, D. M. Hunten, P. G. J. Irwin and T. C. Owen 5. Jovian clouds and haze R. A. West, K. H. Baines, A. J. Friedson, D. Banfield, B. Ragent and F. W. Taylor 6. Dynamics of Jupiter's atmosphere A. P. Ingersoll, T. E. Dowling, P. J. Gierasch, G. S. Orton, P. L. Read, A. Sanchez-Lavega, A. P. Showman, A. A. Simon-Miller and A. R. Vasavada 7. The stratosphere of Jupiter J. I. Moses, T. Fouchet, R. V. Yelle, A. J. Friedson, G. S. Orton, B. Bezard, P. Drossart, G. R. Gladstone, T. Kostiuk and T. A. Livengood 8. Lessons from Shoemaker-Levy 9 about Jupiter and planetary impacts J. Harrington, I. de Pater, S. H. Brecht, D. Deming, V. Meadows, K. Zahnle and P. D. Nicholson 9. Jupiter's thermosphere and ionosphere R. V. Yelle and S. Miller 10. Jovian dust: streams, clouds and rings H. Kruger, M. Horanyi, A. V. Krivov and A. L. Graps 11. Jupiter's ring-moon system J. A. Burns, D. P. Simonelli, M. R. Showalter, D. P. Hamilton, C. C. Porco, H. Throop and L. W. Esposito 12. Jupiter's outer satellites and trojans D. C. Jewitt, S. Sheppard and C. Porco 13. Interior composition, structure and dynamics of the Galilean satellites G. Schubert, J. D. Anderson, T. Spohn and W. B. McKinnon 14. The lithosphere and surface of Io A. S. McEwen, L. P. Keszthelyi, R. Lopes, P. M. Schenk and J. R. Spencer 15. Geology of Europa R. Greeley, C. F. Chyba, J. W. Head III, T. B. McCord, W. B. McKinnon, R. T. Pappalardo and P. Figueredo 16. Geology of Ganymede R. T. Pappalardo, G. C. Collins, J. W. Head III, P. Helfenstein, T. B. McCord, J. M. Moore, L. M. Procktor, P. M. Shenk and J. R. Spencer 17. Callisto J. M. Moore, C. R. Chapman. E. B. Bierhaus, R. Greeley, F. C. Chuang, J. Klemaszewski, R. N. Clark, J. B. Dalton, C. A. Hibbitts, P. M. Schenk, J. R. Spencer and R. Wagner 18. Ages and interiors: the cratering record of the Galilean satellites P. M. Schenk, C. R. Chapman, K. Zahnle and J. M. Moore 19. Satellite atmospheres M. A. McGrath, E. Lellouch, D. F. Strobel, P. D. Feldman and R. E. Johnson 20. Radiation effects on the surfaces of the Galilean satellites R. E. Johnson, R. W. Carlson, J. F. Cooper, C. Paranicas, M. H. Moore and M. C. Wong 21. Magnetospheric interactions with satellites M. G. Kivelson, F. Bagenal, W. S. Kurth, F. M. Neubauer, C. Paranicas and J. Saur 22. Plasma interactions of Io with its plasma torus J. Saur, F. M. Neubauer, J. E. P. Connerney, P. Zarka and M. G. Kivelson 23. The Io neutral clouds and plasma torus N. Thomas, F. Bagenal, T. W. Hill and J. K. Wilson 24. The configuration of Jupiter's magnetosphere K. K. Khurana, M. G. Kivelson, V. M. Vasyliunas, N. Krupp, J. Woch, A. Lagg, B. H. Mauk and W. S. Kurth 25. Dynamics of the Jovian magnetosphere N. Krupp, V. M. Vasyliunas, J. Woch, A. Lagg, K. K. Khurana, M. G. Kivelson, B. H. Mauk, E. C. Roelof, D. J. Williams, S. M. Krimigis, W. S. Kurth, L. A. Frank and W. R. Paterson 26. Jupiter's Aurora J. T. Clarke, D. Grodent, S. W. H. Cowley, E. J. Bunce, P. Zarka, J. E. P. Connerney and T. Satoh 27. Jupiter's inner radiation belts S. J. Bolton, R. M. Thorne, S. Bourdarie, I. de Pater and B. Mauk Appendix 1. Maps and spectra of Jupiter and the Galilean satellites J. R. Spencer, R. W. Carlson, T. L. Becker and J. S. Blue Appendix 2. Planetary parameters J. W. Weiss Index.
486 citations
"Io's volcanic control of Jupiter's ..." refers background in this paper
...While a consensus model is far from complete, its potential elements have been described in several review articles (Schneider et al., 1989; Spencer and Schneider, 1996; Thomas, 1997; Bagenal, 2004)....
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TL;DR: In this paper, the authors report the following results from a decade of infrared radiometry of Io: (1) the average global heat flow is more than approx. 2.5 W/sq.m, large warm (less than or equal to 200 K) volcanic regions dominate the global heat flows, smal high-temperature (greater than or = 300 K) 'hotspots' contribute little to the average heat flow, thermal anomalies on the leading hemisphere contribute about half of the heat flow and a substantial amount of heat is radiated during Io's night, high
Abstract: We report the following results from a decade of infrared radiometry of Io: (1) The average global heat flow is more than approx. 2.5 W/sq.m, (2) large warm (less than or equal to 200 K) volcanic regions dominate the global heat flow, (3) smal high-temperature (greater than or = 300 K) 'hotspots' contribute little to the average heat flow, (4) thermal anomalies on the leading hemisphere contribute about half of the heat flow, (5) a substantial amount of heat is radiated during Io's night, (6) high-temperature (greater than or = 600 K) 'outbursts' occurred during approx. 4% of the nights we observed, (7) 'Loki' is the brightest, persistent, infrared emission feature, and (8) some excess emission is always present at the longitude of Loki, but its intensity and other characteristics change between apparitions. Observations of Io at M(4.8 micrometer), 8.7 micrometer, N(10 micrometer), and Q(20 micrometer) with the Infrared Telescope Facility presented here were collected during nine apparitions between 1983 and 1993. These measurements provide full longitudinal coveraged as well as an eclipse observation and the detection of two outbursts. Reflected sunlight, passive thermal emission, and radiation from thermal anomalies all contribute to the observed flux densities. We find that a new thermophysical model is required to match all the data. Two key elements of this model are (1) a 'thermal reservoir' unit which lowers daytime temperatures, and (2) the 'thermal pedestal effect' which shifts to shorter wavelengths the spectral emission due to the reradiation of solar energy absorbed by the thermal anomalies. The thermal anomalies are modeled with a total of 10 source components at five locations. Io's heat flow is the sum of the power from these components.
217 citations
"Io's volcanic control of Jupiter's ..." refers background in this paper
...Hence, w there is continuity of nebula observations from year to y shorter time resolution issues cannot be addressed with a dataset....
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TL;DR: Io, the innermost of Jupiter's large moons, is one of the most unusual objects in the Solar System as discussed by the authors, which produces a global heat flux 40 times the terrestrial value, producing intense volcanic activity and a global resurfacing rate averaging perhaps 1 cm yr−1.
Abstract: ▪ Abstract Io, innermost of Jupiter's large moons, is one of the most unusual objects in the Solar System. Tidal heating of the interior produces a global heat flux 40 times the terrestrial value, producing intense volcanic activity and a global resurfacing rate averaging perhaps 1 cm yr−1. The volcanoes may erupt mostly silicate lavas, but the uppermost surface is dominated by sulfur compounds including SO2 frost. The volcanoes and frost support a thin, patchy SO2 atmosphere with peak pressure near 10−8 bars. Self-sustaining bombardment of the surface and atmosphere by Io-derived plasma trapped in Jupiter's magnetosphere causes escape of material from Io (predominantly sulfur, oxygen, and sodium atoms, ions, and molecules) at a rate of about 103 kg s−1. The resulting Jupiter-encircling torus of ionized sulfur and oxygen dominates the Jovian magnetosphere and, together with an extended cloud of neutral sodium, is readily observable from Earth.
184 citations
"Io's volcanic control of Jupiter's ..." refers background in this paper
...Keywords: Io; Jupiter, magnetosphere; Satellites, atmospheres; Volcanism nds phe and the ter’s and surd Io niza ally on, ter’s r in ave ronto a eres, ear iled the ecraft ervabit. n vol- proain e in a onents 997; d with...
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...They are estimated to occur 3% o time globally(Spencer and Schneider, 1996)....
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...In 1995, Tiermes Patera and Ukko Patera erupted a tectable levels for 60–80 days and 30–70 days, respecti Together, these represent 14 of the 23 non-Loki erup measurements in the total dataset of 120 nights....
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...While a c sensus model is far from complete, its potential elem have been described in several review articles(Schneider et al., 1989; Spencer and Schneider, 1996; Thomas, 1 Bagenal, 2004)....
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TL;DR: In this paper, a three-dimensional, stationary, two-fluid plasma model for electrons and one ion species was developed to understand the local interaction of Io's atmosphere with the Io plasma torus and the formation of Io ionosphere.
Abstract: A three-dimensional, stationary, two-fluid plasma model for electrons and one ion species was developed to understand the local interaction of Io's atmosphere with the Io plasma torus and the formation of Io's ionosphere. Our model calculates, self-consistently, the plasma density, the velocity and the temperatures of the ions and electrons, and the electric field for a given neutral atmosphere and imposed Io plasma torus conditions but assumes for the magnetic field the constant homogeneous Jovian field. With only photoionization in a pure SO2 atmosphere it is impossible to correctly model the plasma measurements by the Galileo spacecraft. With collisional ionization and photoionization the observations can be successfully modeled when the neutral atmospheric column density is Ncol = 6 × 1020 m−2 and the atmospheric scale height is H = 100 km. The energy reservoir of the Io plasma torus provides via electron heat conduction the necessary thermal energy for the maintenance of the collisional ionization process and thus the formation of Io's ionosphere. Anisotropic conductivity is shown numerically as well as analytically to be essential to understand the convection patterns and current systems across Io. The electric field is very greatly reduced, because the ionospheric conductances far exceed the Alfven conductance ΣA, and also strongly twisted owing to the Hall effect. We find that the electric field is twisted by an analytic angle tan Θtwist = Σ2/(Σ1 + 2ΣA) from the anti-Jupiter direction toward the direction of corotation for constant values of the Pedersen and Hall conductances Σ1 and Σ2 within a circle encompassing Io's ionosphere. Because the electron velocity is approximately equal to the E × B drift velocity, the electron flow trajectories are twisted by the same angle toward Jupiter, with E and B the electric and magnetic fields, respectively. Since Σ1 ∼ Σ2, the electron flow is strongly asymmetric during convection across Io, and the magnitude of this effect is directly due to the Hall conductivity. In contrast, the ions are diverted slightly away from Jupiter when passing Io. Large electric currents flow in Io's ionosphere owing to these substantially different flow patterns for electrons and ions, and our calculations predict that a total electric current of 5 million A was carried in each Alfven wing during the Galileo flyby. We also find a total Joule heating rate dissipated in Io's ionosphere of P = 4.2 × 1011 W.
144 citations
TL;DR: The detection of NaCl in Io's atmosphere is reported; it constitutes only ∼0.3% when averaged over the entire disk, but is probably restricted to smaller regions than SO2 because of its rapid photolysis and surface condensation.
Abstract: The atmosphere of Jupiter's satellite Io is extremely tenuous, time variable and spatially heterogeneous. Only a few molecules—SO2, SO and S2—have previously been identified as constituents of this atmosphere, and possible sources1,2,3,4 include frost sublimation, surface sputtering and active volcanism. Io has been known5,6 for almost 30 years to be surrounded by a cloud of Na, which requires an as yet unidentified atmospheric source of sodium. Sodium chloride has been recently proposed as an important atmospheric constituent, based on the detection of chlorine in Io's plasma torus7,8 and models of Io's volcanic gases9 . Here we report the detection of NaCl in Io's atmosphere; it constitutes only ∼0.3% when averaged over the entire disk, but is probably restricted to smaller regions than SO2 because of its rapid photolysis and surface condensation10. Although the inferred abundance of NaCl in volcanic gases is lower than predicted9, those volcanic emissions provide an important source of Na and Cl in Io's neutral clouds and plasma torus.
100 citations
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...%)...
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...…erable evidence for calling it NaCl+. Observations of Cl+ in the plasma torus(Kuppers and Schneider, 2000), direct detection of NaCl in Io’s atmosphere(Lellouch et al., 2003), and a recent set of atmospheric models for volcanic co tions offer ample evidence to base further discussions u NaCl being…...
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