Detection of H<sub>3</sub><sup>+</sup>auroral emission in Jupiter’s 5-micron window

Giles, Rohini; Fletcher, Leigh N.; Irwin, Patrick G. J.; Melin, Henrik; Stallard, T.

doi:10.1051/0004-6361/201628170

Cited by 10 publications

(7 citation statements)

References 15 publications

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“…Melin et al () and Tao et al () found that non‐LTE effects increase with altitude, where the temperature is higher and the density is lower. Giles et al () detected H 3 + lines in Jupiter's auroral regions in the 5 μm window and this was the first and only study to date to measure all three temperatures simultaneously. They obtained a kinetic temperature of 1390 ± 160 K, a rotational temperature of 960 ± 40 K, and a vibrational temperature of 925 ± 25 K. These three temperature values are not all in agreement with each other, which indicates a departure from LTE.…”

Section: Discussionmentioning

confidence: 92%

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: Discussionmentioning

confidence: 92%

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

et al. 2018

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“…The Juno mission Bolton et al [2017] and Connerney et al [2017] provides the first occasion to study the South Pole aurora of Jupiter in homogeneous and simultaneous observing conditions. Past analyses [Kim et al, 2009[Kim et al, , 2015Giles et al, 2016], conducted from ground-based observations, have been challenged by using spectra obtained on different dates with different sky conditions. One of the primary objectives of the Juno mission is to clarify the auroral mechanisms at play.…”

Section: Research Lettermentioning

confidence: 99%

Preliminary JIRAM results from Juno polar observations: 2. Analysis of the Jupiter southern H₃⁺ emissions and comparison with the north aurora

Adriani

Mura

Moriconi

et al. 2017

Geophysical Research Letters

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The Jupiter InfraRed Auroral Mapper (JIRAM) aboard Juno observed the Jovian South Pole aurora during the first orbit of the mission. H3+ (trihydrogen cation) and CH4 (methane) emissions have been identified and measured. The observations have been carried out in nadir and slant viewing both by a L‐filtered imager and a 2–5 μm spectrometer. Results from the spectral analysis of the all observations taken over the South Pole by the instrument are reported. The coverage of the southern aurora during these measurements has been partial, but sufficient to determine different regions of temperature and abundance of the H3+ ion from its emission lines in the 3–4 μm wavelength range. Finally, the results from the southern aurora are also compared with those from the northern ones from the data taken during the same perijove pass and reported by Dinelli et al. (2017).

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“…CRIRES is a cryogenic high-resolution infrared echelle spectrograph [Käufl et al, 2004], which provides long-slit (0.2×40") spectroscopy with a resolving power of 96,000. The CRIRES observations used in this paper have previously been used to study the latitudinal variability in Jupiter's tropospheric disequilibrium species [Giles et al, 2017] and the H 3 + auroral emission [Giles et al, 2016]. In this paper, these CRIRES observations are used to study NH 3 absorption in the 5-µm window.…”

Section: Crires Observationsmentioning

confidence: 99%

Ammonia in Jupiter's Troposphere From High‐Resolution 5 μm Spectroscopy

Giles

Fletcher

Irwin

et al. 2017

Geophysical Research Letters

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Jupiter's tropospheric ammonia (NH 3) abundance is studied using spatially resolved 5 μm observations from the cryogenic high-resolution infrared spectrograph (CRIRES) at the European Southern Observatory's Very Large Telescope. The high-resolving power (R = 96, 000) allows the line shapes of three NH 3 absorption features to be resolved. We find that within the 1-4 bar pressure range, the NH 3 abundance decreases with altitude. The instrument slit was aligned north-south along Jupiter's central meridian, allowing us to search for latitudinal variability. There is considerable uncertainty in the large-scale latitudinal variability, as the increase in cloud opacity in zones compared to belts can mask absorption features. However, we do find evidence for a strong NH 3 enhancement at 4-6 ∘ N, consistent with a localized "ammonia plume" on the southern edge of Jupiter's North Equatorial Belt.

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Detection of H₃⁺auroral emission in Jupiter’s 5-micron window

Cited by 10 publications

References 15 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

Preliminary JIRAM results from Juno polar observations: 2. Analysis of the Jupiter southern H₃⁺ emissions and comparison with the north aurora

Ammonia in Jupiter's Troposphere From High‐Resolution 5 μm Spectroscopy

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Detection of H3+auroral emission in Jupiter’s 5-micron window

Cited by 10 publications

References 15 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

Preliminary JIRAM results from Juno polar observations: 2. Analysis of the Jupiter southern H3+ emissions and comparison with the north aurora

Ammonia in Jupiter's Troposphere From High‐Resolution 5 μm Spectroscopy

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Resources

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Detection of H₃⁺auroral emission in Jupiter’s 5-micron window

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

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

Preliminary JIRAM results from Juno polar observations: 2. Analysis of the Jupiter southern H₃⁺ emissions and comparison with the north aurora