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Journal ArticleDOI

Io's volcanic control of Jupiter's extended neutral clouds

01 Aug 2004-Icarus (Academic Press)-Vol. 170, Iss: 2, pp 430-442

AbstractDramatic changes in the brightness and shape of Jupiter's extended sodium nebula are found to be correlated with the infrared emission brightness of Io. Previous imaging and modeling studies have shown that varying appearances of the nebula correspond to changes in the rate and the type of loss mechanism for atmospheric escape from Io. Similarly, previous IR observational studies have assumed that enhancements in infrared emissions from Io correspond to increased levels of volcanic (lava flow) activity. In linking these processes observationally and statistically, we conclude that silicate volcanism on Io controls both the rate and the means by which sodium escapes from Io's atmosphere. During active periods, molecules containing sodium become an important transient in Io's upper atmosphere, and subsequent photochemistry and molecular-ion driven dynamics enhance the high speed sodium population, leading to the brightest nebulas observed. This is not the case during volcanically quiet times when omni-present atmospheric sputtering ejects sodium to form a modest, base-level nebula. Sodium's role as a “trace gas” of the more abundant species of sulfur (S) and oxygen (O) is less certain during volcanic episodes. While we suggest that volcanism must also affect the escape rates of S and O, and consequently their extended neutral clouds, the different roles played by lava and plume sources for non-sodium species are far too uncertain to make definitive comparisons at this time.

Topics: Atmospheric escape (54%), Population (52%), Jupiter (52%), Atmosphere (52%), Nebula (51%)

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Citations
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Journal ArticleDOI
Abstract: We present new optical coronagraphic data of Fomalhaut obtained with HST/STIS in 2010 and 2012. Fomalhaut b is recovered at both epochs to high significance. The observations include the discoveries of tenuous nebulosity beyond the main dust belt detected to at least 209AU projected radius, and a approx. 50AU wide azimuthal gap in the belt northward of Fomalhaut b. The two epochs of Space Telescope Imaging Spectrograph (STIS) photometry exclude optical variability greater than 35%. A Markov chain Monte Carlo analysis demonstrates that the orbit of Fomalhaut b is highly eccentric, with e = 0.8 +/- 0.1, a = 177 +/- 68AU, and q = 32 +/- 24AU. Fomalhaut b is apsidally aligned with the belt and 90% of allowed orbits have mutual inclination <=36 deg. Fomalhaut b's orbit is belt crossing in the sky plane projection, but only 12% of possible orbits have ascending or descending nodes within a 25AU wide belt annulus. The high eccentricity invokes a dynamical history where Fomalhaut b may have experienced a significant dynamical interaction with a hypothetical planet Fomalhaut c, and the current orbital configuration may be relatively short-lived. The Tisserand parameter with respect to a hypothetical Fomalhaut planet at 30AU or 120AU lies in the range 2-3, similar to highly eccentric dwarf planets in our solar system. We argue that Fomalhaut b's minimum mass is that of a dwarf planet in order for a circumplanetary satellite system to remain bound to a sufficient radius from the planet to be consistent with the dust scattered light hypothesis. In the coplanar case, Fomalhaut b will collide with the main belt around 2032, and the subsequent emergent phenomena may help determine its physical nature.

168 citations


Cites background from "Io's volcanic control of Jupiter's ..."

  • ...These variations are correlated to the volcanic activity of Io (Mendillo et al. 2004)....

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Journal ArticleDOI
01 Mar 2008-Icarus
Abstract: In this fourth paper in a series, we present a model of the remarkable temporal and azimuthal variability of the Io plasma torus observed during the Cassini encounter with Jupiter. Over a period of three months, the Cassini Ultraviolet Imaging Spectrograph (UVIS) observed a dramatic variation in the average torus composition. Superimposed on this long-term variation, is a 10.07-h periodicity caused by an azimuthal variation in plasma composition subcorotating relative to System III longitude. Quite surprisingly, the amplitude of the azimuthal variation appears to be modulated at the beat frequency between the System III period and the observed 10.07-h period. Previously, we have successfully modeled the months-long compositional change by supposing a factor of three increase in the amount of material supplied to Io's extended neutral clouds. Here, we extend our torus chemistry model to include an azimuthal dimension. We postulate the existence of two azimuthal variations in the number of superthermal electrons in the torus: a primary variation that subcorotates with a period of 10.07 h and a secondary variation that remains fixed in System III longitude. Using these two hot electron variations, our model can reproduce the observed temporal and azimuthal variations observed by Cassini UVIS.

79 citations


Cites background from "Io's volcanic control of Jupiter's ..."

  • ...When torus ions becomes neutralized, the resulting atom is no longer constrained by Jupiter’s magnetic field and is quickly lost from the Io torus, eventually forming an extended nebula hundreds of jovian radii in size (Mendillo et al., 2004)....

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Journal ArticleDOI
01 Jul 2006-Icarus
Abstract: The Cassini spacecraft encountered Jupiter in late 2000. Within more than 1 AU of the gas giant the Cosmic Dust Analyser onboard the spacecraft recorded the first ever mass spectra of jovian stream particles. To determine the chemical composition of particles, a comprehensive statistical analysis of the dataset was performed. Our results imply that the vast majority (>95%) of the observed stream particles originate from the volcanic active jovian satellite Io from where they are sprinkled out far into the Solar System. Sodium chloride (NaCl) was identified as the major particle constituent, accompanied by sulphurous as well as potassium bearing components. This is in contrast to observations of gas in the ionian atmosphere, its co-rotating plasma torus, and the neutral cloud, where sulphur species are dominant while alkali and chlorine species are only minor components. Io has the largest active volcanoes of the Solar System with plumes reaching heights of more than 400 km above the moons surface. Our in situ measurements indicate that alkaline salt condensation of volcanic gases inside those plumes could be the dominant formation process for particles reaching the ionian exosphere.

66 citations


Cites background from "Io's volcanic control of Jupiter's ..."

  • ...Furthermore, its abundance is dependent on the volcanic activity on the moon (Lellouch et al., 2003; Mendillo et al., 2004)....

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  • ...It is evident that it does escape from the moon’s gravitational influence, forming the major source for Na and Cl species in the ionian system (Fegley and Zolotov, 2000; Küppers and Schneider, 2000; Schneider et al., 2000; Moses et al., 2002a; Lellouch et al., 2003; Mendillo et al., 2004)....

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Journal ArticleDOI
15 Nov 2015-Icarus
Abstract: Jupiter’s sodium nebula, which originates from Io’s volcanic gas, shows variations in its brightness due to the volcanic activity on Io. Imaging observation of D-line brightness in the sodium nebula was performed from 2013 through 2015 in a conjunction with the HISAKI mission. The D-line brightness of the sodium nebula had been stably faint and dim until January 2015, but it showed a distinct enhancement from February through March, 2015. The brightness increased by three times during this enhancement. Details in variations of Jupiter’s sodium nebula are shown in this paper.

34 citations


Book ChapterDOI
01 Jan 2007

32 citations


References
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Book
01 Jan 2004
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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Journal ArticleDOI
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.

201 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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Journal ArticleDOI
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.

180 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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Journal ArticleDOI
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.

131 citations


Journal ArticleDOI
22 Nov 1990-Nature
Abstract: THE detection of a cloud of neutral sodium near Jupiter's moon Io1 has led to the use of sodium as a tracer of processes in the jovian environment. Although relatively rare in the Io–Jupiter system, sodium atoms are easily detected because of their high efficiency for scattering sunlight at wavelengths of ∼5,890 A. Direct imaging of the sodium cloud2 has suggested that sodium atoms are a common feature close to Io (at distances of about six Io radii, RIo) and detection of high-speed sodium jets3 suggested that sodium is present only sporadically at ∼30/RIo (ref. 4). Sodium emission has been reported at greater distances5, even as far as 60RIo (ref. 6) but these observations have been controversial in view of suggestions7 that the detection of sodium beyond ∼10RIo was implausible on theoretical grounds and probably indistinguishable from terrestrial sodium airglow. Here we report on the detection of sodium to distances beyond ∼400 RI, an observation that requires the ejection rate of sodium atoms to be increased. By relating the shape of this great nebula to conditions in the plasma torus surrounding Jupiter, we show that ground-based imaging techniques can provide information about distant planetary magnetospheres.

92 citations


"Io's volcanic control of Jupiter's ..." refers background or methods in this paper

  • ...The imaging technique used to observe Jup sodium nebula has been described in several previous w (Mendillo et al., 1990; Baumgardner and Mendillo, 199 Baumgardner et al., 1993)....

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  • ...The distant Na∗ atoms in the nebula were successfu imaged for the first time in December 1989(Mendillo et al., 1990; Flynn et al., 1994)and at yearly intervals since then....

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  • ...Given the primary role of volcanic activity (lava flow and plumes) in producing Io’s atmosphere, it is reason to expect that Io’s sodium clouds and plasma torus sh be affected by changes in Io’s volcanism....

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