Thermal Structure of Jupiter's Upper Atmosphere Derived from the Galileo Probe

Seiff, A.; Kirk, Donn B.; Knight, T. C. D.; Young, L. A.; Milos, Frank S.; Venkatapathy, Ethiraj; Mihalov, J. D.; Blanchard, Robert C.; Young, Richard E.; Schubert, G.

doi:10.1126/science.276.5309.102

Cited by 90 publications

(68 citation statements)

References 13 publications

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“…These temperatures are much lower than those inferred from rotational analyses of high-resolution spectra of the Ha Lyman and Werner band systems, which are in the range 300 to 850 K at the peak of the emitting layer, with most values near 400-500 K [T ration et al Finally, we find that the temperatures at the altitude of peak electron energy deposition for our Galileobased thermospheric models are less than 200 K and are much smaller than those derived from rotational analysis of HST data. We conclude that the auroral thermosphere is considerably hotter in the 0.5-10/•bar region than the near-equatorial region that was sampled by the Galileo probe [Seiff et al, 1997] and from which our pressure and temperature profiles were constructed. Calculations for a background model with a more realistic auroral temperature profile are in progress.…”

Section: Temperatures and Pressures At The Auroral Energy Deposition mentioning

confidence: 99%

Chemistry of the Jovian auroral ionosphere

Perry¹,

Kim²,

Fox³

et al. 1999

J. Geophys. Res.

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Abstract. We have investigated the chemistry of the Jovian auroral thermosphere-/ionosphere by modeling the precipitation of high-energy electrons into the auroral zones using a multistream electron-transport code and three model thermospheres' a standard model based on pressure and temperature data from Galileo, and two additional models that are characterized by enhanced eddy diffusion coefficients. We have predicted the effects of precipitation of monoenergetic electrons with energies between 20 and 100 keV with energy fluxes of about 11 ergs cm-2s -•. We have derived the column densities of H2, H, CH4, and C2H2 above the altitudes of peak energy deposition. For methane column densities similar to those determined from IUE and Hubble Space Telescope H2 spectral data, we find that for our standard model, the most likely electron energies are in the 45-55 keV range. For the enhanced eddy diffusion models the energies are lower. We present ion density profiles, H density profiles, and production profiles for the most important H2 and H emissions. The predicted H column densities are in the range (1 -6) x 10 •8 cm -2 for the standard model and are smaller for the enhanced eddy diffusion models. We find that the temperatures near the altitude of peak energy deposition vary from 160 to 200 K and are significantly lower than those derived from rotational analyses of auroral H2 emissions, which average 400-500 K. This indicates that the auroral thermosphere is considerably warmer than those at lower latitudes that were measured by the Voyager spacecraft or the Galileo probe.

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Section: Temperatures and Pressures At The Auroral Energy Deposition mentioning

confidence: 99%

Chemistry of the Jovian auroral ionosphere

Perry¹,

Kim²,

Fox³

et al. 1999

J. Geophys. Res.

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“…Assuming that these equatorial X rays are caused by the precipitation of energetic (>300 keV nucteon -•) S and O ions out of Jupiter's inner radiation belt, Waite et al [1997] studied the implications of these precipitating heavy ions for the heating of the atmosphere. Their model calculations showed that a height-integrated heating rate of 0.08-3 ergs cm -2 s -•, with a preferred value of 0.2 ergs cm -2 s -•, can result in substantial heating of the atmosphere that may account for a large fraction of the upper atmosphere temperature structure observed by the Galileo probe's atmospheric structure instrument [Seiff et al, 1996[Seiff et al, , 1997.…”

Section: ] That Precipitating Energetic (>700 Kev Nucleon -•)mentioning

confidence: 99%

Auroral emissions of the giant planets

Bhardwaj¹,

Gladstone²

2000

Reviews of Geophysics

154

128

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Abstract. Auroras are (generally) high-latitude atmospheric emissions that result from the precipitation of energetic charged particles from a planet's magnetosphere. Auroral emissions from the giant planets have been observed from ground-based observatories, Earthorbiting satellites (e.g., International Ultraviolet Explorer (IUE), Hubble Space Telescope (HST), and R6entgensatellit (ROSAT)), flyby spacecraft (e.g., Voyager 1 and 2), and orbiting spacecraft platforms (e.g., Galileo) at X-ray, ultraviolet (UV), visible, infrared (IR), and radio wavelengths. UV, visible, and IR auroras are atmospheric emissions, produced or initiated when ambient atmospheric species are excited through collisions with the precipitating particles, while radio and X-ray auroras are beam emissions, produced by the precipitating species themselves. The emissions at different wavelengths provide unique and complementary information, accessible to remote sensing, about the key physical processes operating in the atmospheric and magnetospheric regions where they originate. This paper reviews the development of our current understanding of auroral emissions from Jupiter, Saturn, Uranus, and Neptune, as revealed through multispectral observations and supplemented by plasma measurements.

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“…The temperature at the Jovian homopause, which is located at 0.1-1 μbar (e.g., Yelle & Miller 2004), is ∼160 K (Seiff et al 1997). Thus, for a planet like HD209458b, with g J /g ≈ 2 and v τ /v τ J ≈ 5, we obtain K τ ≈ 10 4 -10 5 m 2 s −1 near the 1 μbar level at 0.047 AU (using T /T J ≈ 7) and K τ ≈ 10 3 -10 4 m 2 s −1 at 0.8 AU (using T /T J ≈ 2).…”

Section: The Upper and Lower Boundariesmentioning

confidence: 99%

Ionization of Extrasolar Giant Planet Atmospheres

Koskinen

Cho

Achilleos

et al. 2010

ApJ

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Many extrasolar planets orbit close in and are subject to intense ionizing radiation from their host stars. Therefore, we expect them to have strong, and extended, ionospheres. Ionospheres are important because they modulate escape in the upper atmosphere and can modify circulation, as well as leave their signatures, in the lower atmosphere. In this paper, we evaluate the vertical location Z I and extent D I of the EUV ionization peak layer. We find that Z I ≈ 1-10 nbar-for a wide range of orbital distances (a = 0.047-1 AU) from the host star-and D I /H p 15, where H p is the pressure scale height. At Z I , the plasma frequency is ∼80-450 MHz, depending on a. We also study global ion transport, and its dependence on a, using a three-dimensional thermosphere-ionosphere model. On tidally synchronized planets with weak intrinsic magnetic fields, our model shows only a small, but discernible, difference in electron density from the dayside to the nightside (∼9 × 10 13 m −3 to ∼2 × 10 12 m −3 , respectively) at Z I . On asynchronous planets, the distribution is essentially uniform. These results have consequences for hydrodynamic modeling of the atmospheres of close-in extrasolar giant planets.

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Thermal Structure of Jupiter's Upper Atmosphere Derived from the Galileo Probe

Cited by 90 publications

References 13 publications

Chemistry of the Jovian auroral ionosphere

Chemistry of the Jovian auroral ionosphere

Auroral emissions of the giant planets

Ionization of Extrasolar Giant Planet Atmospheres

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