JIRAM, the Jovian Infrared Auroral Mapper

Throughout the first orbit of the NASA Juno mission around Jupiter, the Jupiter InfraRed Auroral Mapper (JIRAM) targeted the northern and southern polar regions several times. The analyses of the acquired images and spectra confirmed a significant presence of methane (CH4) near both poles through its 3.3 μm emission overlapping the H3+ auroral feature at 3.31 μm. Neither acetylene (C2H2) nor ethane (C2H6) have been observed so far. The analysis method, developed for the retrieval of H3+ temperature and abundances and applied to the JIRAM‐measured spectra, has enabled an estimate of the effective temperature for methane peak emission and the distribution of its spectral contribution in the polar regions. The enhanced methane inside the auroral oval regions in the two hemispheres at different longitude suggests an excitation mechanism driven by energized particle precipitation from the magnetosphere.

Section: Jiram Instrument and Data Managementmentioning

confidence: 99%

Preliminary JIRAM results from Juno polar observations: 3. Evidence of diffuse methane presence in the Jupiter auroral regions

Moriconi

Adriani

Dinelli

et al. 2017

“…Preliminary results from Juno's magnetospheric science are summarized in Connerney et al [2017a]. Juno includes a comprehensive suite of instruments to characterize Jupiter's magnetosphere [Bagenal et al, 2014]: MAG is a magnetometer [Connerney, 2017b], the Jovian Auroral Distributions Experiment (JADE) is an ion and electron plasma instrument [McComas et al, 2013], Jupiter Energetic Particle Detector Instrument (JEDI) is an energetic ion and electron instrument [Mauk et al, 2014], Waves is a plasma waves instrument, UVS is a UV spectrometer [Gladstone et al, 2014], and Jovian Infrared Auroral Mapper (JIRAM) is an infrared imager [Adriani et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Electron beams and loss cones in the auroral regions of Jupiter

Allegrini

Bagenal

Bolton

et al. 2017

We report on the first observations of 100 eV to 100 keV electrons over the auroral regions of Jupiter by the Jovian Auroral Distributions Experiment (JADE) on board the Juno mission. The focus is on the regions that were magnetically connected to the main auroral oval. Amongst the most remarkable features, JADE observed electron beams, mostly upward going but also some downward going in the south, at latitudes from ~69° to 72° and ~ −66° to −70° corresponding to M shells (“M” for magnetic) from ~18 to 54 and ~28 to 61, respectively. The beams were replaced by upward loss cones at lower latitudes. There was no evidence of strongly accelerated downward electrons analogous to the auroral “inverted Vs” at Earth. Rather, the presence of upward loss cones suggests a diffuse aurora process. The energy spectra resemble tails of distributions or power laws (suggestive of a stochastic acceleration process) but can also have some clear enhancements or even peaks generally between 1 and 10 keV. Electron intensities change on timescales of a second or less at times implying that auroral structures can be of the order of a few tens of kilometers.

“…The Jovian Infrared Auroral Mapper (JIRAM) [Adriani et al, 2008[Adriani et al, , 2014[Adriani et al, , 2016 is an imaging spectrometer on board the Juno spacecraft, which started the prime mission around Jupiter in August 2016 [Bolton et al, 2017].…”

Section: Introductionmentioning

confidence: 99%

Infrared observations of Jovian aurora from Juno's first orbits: Main oval and satellite footprints

Mura

Adriani

Altieri

et al. 2017

The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3+ infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io “tail” persists for ~3 h after the passage of the satellite flux tube. Multi‐arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3+ emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions.