Spectro-imaging observations of Jupiter’s 2μm auroral emission. II: Thermospheric winds

Chaufray, Jean‐Yves; Greathouse, T. K.; Gladstone, G. R.; Waite, J. H.; Maillard, J. P.; Majeed, T.; Bougher, S. W.; Lellouch, E.; Drossart, P.

doi:10.1016/j.icarus.2010.11.021

Cited by 22 publications

(46 citation statements)

References 58 publications

(98 reference statements)

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“…There are very limited measurements of the neutral velocity in the thermosphere. The only two measurements of neutral winds measured in the auroral region were taken by Chaufray et al (, ). Using observations of the H Ly‐α line profile taken with HST‐STIS of the northern auroral region, Chaufray et al () calculated a velocity of ~4–8 km/s at ~1,500 km above the 1‐bar level.…”

Section: Resultsmentioning

confidence: 99%

“…Using observations of the H Ly‐α line profile taken with HST‐STIS of the northern auroral region, Chaufray et al () calculated a velocity of ~4–8 km/s at ~1,500 km above the 1‐bar level. Through IR observations using the Fourier transform spectrometer (FTS/BEAR) instrument at the Canada‐France Hawaii Telescope (CFHT), Chaufray et al () derived an upper limit on the LOS velocity of <1.0 km/s for the H 2 , at altitude ~560–690 km above the 1‐bar level (Uno et al, ). Models such as Achilleos et al (), Bougher et al (), and Tao et al () show that the neutral wind velocity remains less than ~1 km/s.…”

Section: Resultsmentioning

confidence: 99%

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Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

et al. 2018

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We present a detailed study of the H3+ auroral emissions at Jupiter, using data taken on 31 December 2012 with the long‐slit Echelle spectrometer CRIRES (ESO‐VLT). From this data set the rotational temperature of the H3+ ions in Jupiter's upper atmosphere was calculated using the ratio of the ν2 Q(1,0−) and ν2 Q(3,0−) fundamental emission lines. The entire northern auroral region was observed, providing a highly detailed view of ionospheric temperatures, which were mapped onto polar projections. The temperature range we derive in the northern auroral region is ~750–1000 K, which is consistent with past studies, although the temperature structure differs. We identify two broad regions which exhibit temperature changes over a short period of time (~80 minutes). We propose that the changes in temperature could be due to a local time change in particle precipitation energy, or they could be caused by dynamic temperature changes generated in the neutral thermosphere due to the magnetospheric response to a transient enhancement of solar wind dynamic pressure, as predicted by models. By comparing the H3+ temperature, column density, total emission, and line‐of‐sight velocity, we were unable to identify a single dominant mechanism responsible for the energetics in Jupiter's northern auroral region. The comparison reveals that there is complex interplay between heating by impact from particle precipitation and Joule heating, as well as cooling by the H3+ thermostat effect.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

et al. 2018

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“…In our observed results, the H 3 + overtone (~650–1000 km), H 3 + hot overtone (~550–1050 km), and IR H 2 emissions (~700–950 km) appeared at similar altitudes. Chaufray et al [] showed that the velocity of the H 3 + ion drift (~3 km/s) was larger than the neutral wind velocity of H 2 (<1 km/s), with the ratio V (H 2 )/ V (H 3 + ) < 0.33. They suggested that H 2 emission with lower velocity is from a lower altitude than that of H 3 + emission with higher velocity.…”

Section: Resultsmentioning

confidence: 99%

“…This suggests a difference in their emission altitudes, heating process, and the energy transfer between the ionized and neutral polar atmospheres. From the same data set, Chaufray et al [] showed that the line of sight velocity of H 2 molecules, determined from the Doppler shift of the emission lines, was <1.0 km/s, which is lower than that of the H 3 + ions measured at 3.1 ± 0.4 km/s. This result could have originated from the difference in altitudes sounded by these emission lines.…”

Section: Introductionmentioning

confidence: 99%

Vertical emissivity profiles of Jupiter's northern H₃⁺ and H₂ infrared auroras observed by Subaru/IRCS

et al. 2014

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We resolved the vertical emissivity profiles of H 3 + overtone, H 3 + hot overtone, and H 2 emission lines of the Jovian northern auroras in K band obtained in December 2011 observed by the IR Camera and Spectrograph of the Subaru 8.2 m telescope with the adaptive optics system (AO188). The spatial resolution achieved was~0.2 arcsec, corresponding to~600 km at Jupiter. We derived the vertical emissivity profiles at three polar regions close to the Jovian limb. The H 3 + overtone and H 3 + hot overtone lines had similar peak altitudes of 700-900 km and 680-950 km above the 1 bar level, which were 100-300 km and 150-420 km lower, respectively, than the model values. On the contrary, the H 2 peak emission altitude was high, 590-720 km above the 1 bar level. It was consistent with the value expected for precipitation of~1 keV electron, which favors a higher-altitude emissivity profile. We concluded that the lower peak altitudes of H 3 + overtone and hot overtone lines were caused by the nonlocal thermodynamic equilibrium effect stronger than the model assumption. We could reproduce the observational emissivity profiles from the model by including this effect. It has been proposed that neutral H 2 and ionized H 3 + emissions can have different source altitudes because of their different morphologies and velocities; however, our observed results with a general circulation model show that the peak emission altitudes of H 3 + and H 2 can be similar even with different velocities.

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“…Raynaud et al (2004) observed a H + 3 'hotspot' on Jupiter's northern aurora using the Fourier Transform Spectrometer (FTS) mounted on the Canada France Hawaii Telescope (CFHT) in the 2 µm region. This region had a temperature 250 K higher than the rest of the auroral region, which had an average temperature of ∼1150 K. Using the same data, Chaufray et al (2011) were able to simultaneously derive, for the first time, the H + 3 ion velocity and the neutral H 2 velocity, showing that the 'hot-spot' had an ion velocity of 3.1±0.4 kms −1 , whereas the neutral atmosphere rotated with an upper limit velocity of 1 km s −1 . The intensity (thin) and velocity (bold) profiles can be seen in Figure 19b, showing regions of corotation (steep gradients), sub-corotation (shallow gradients), and stagnation (flat).…”

Section: Latitudinal Cutsmentioning

confidence: 93%

Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

et al. 2014

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Spectro-imaging observations of Jupiter’s 2μm auroral emission. II: Thermospheric winds

Cited by 22 publications

References 58 publications

Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Vertical emissivity profiles of Jupiter's northern H₃⁺ and H₂ infrared auroras observed by Subaru/IRCS

Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

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Spectro-imaging observations of Jupiter’s 2μm auroral emission. II: Thermospheric winds

Cited by 22 publications

References 58 publications

Mapping H3+ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Mapping H3+ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Vertical emissivity profiles of Jupiter's northern H3+ and H2 infrared auroras observed by Subaru/IRCS

Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra

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Resources

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Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Mapping H₃⁺ Temperatures in Jupiter's Northern Auroral Ionosphere Using VLT‐CRIRES

Vertical emissivity profiles of Jupiter's northern H₃⁺ and H₂ infrared auroras observed by Subaru/IRCS