Hot CH_4 in the polar regions of Jupiter
We have obtained 3.3–3.4-μm spectro-images of Jupiter including CH_4 and H_3^+ emission lines from both polar regions at the Gemini North telescope. We find that the peak of the 3-μm CH_4 northern bright spot is located at ∼200° (SysIII) longitude, ∼20° west of the center of the 8-μm north-polar bright spot, and does not coincide with the 3-μm H_3^+ bright spot. We derive high temperatures (500–850 K) from CH_4 rotational lines on the bright spots of both polar regions, above the 1-μbar pressure level, while we find cooler temperatures (<350 K) over the 8-μm spot. The intensity ratios of the various 3-μm 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-μm thermal emission.
© 2015 Elsevier. Received 19 January 2015; Revised 27 March 2015; Accepted 7 May 2015; Available online 15 May 2015. This paper is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). SJK acknowledges support from the Brain Korea 21 Plus (BK21+) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology, and from the Korean Astronomy & Space Science Institute under the R&D program supervised by the Ministry of Science, ICT and Future Planning.