Hot CH4 in the polar regions of Jupiter

We have obtained 3.3–3.4-lm spectro-images of Jupiter including CH4 and H3 emission lines from both polar regions at the Gemini North telescope. We find that the peak of the 3-lm CH4 northern bright spot is located at 200 (SysIII) longitude, 20 west of the center of the 8-lm north-polar bright spot, and does not coincide with the 3-lm H3 bright spot. We derive high temperatures (500–850 K) from CH4 rotational lines on the bright spots of both polar regions, above the 1-lbar pressure level, while we find cooler temperatures (<350 K) over the 8-lm spot. The intensity ratios of the various 3-lm vibrational bands of CH4 are roughly constant, indicating that the upper states of these bands are mostly populated by non-thermal excitation mechanisms, such as auroral particle precipitation and/or Joule heating, in contrast with the 8-lm thermal emission. 2015 Elsevier Inc. All rights reserved.