Recovery and characterization of Neptune’s near-polar stratospheric hot spot
Images of Neptune obtained in 2006 at ESO's Very Large Telescope (Orton et al., 2007, Astronomy & Astrophysics 473, L5) revealed a near-polar hot spot near 70°S latitude that was detectable in filters sampling both stratospheric methane (7 μm) and ethane (∼12 μm) emission. Such a feature wa...
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ftcaltechauth:oai:authors.library.caltech.edu:32974 2023-05-15T18:23:22+02:00 Recovery and characterization of Neptune’s near-polar stratospheric hot spot Orton, Glenn S. Fletcher, Leigh N. Liu, Junjun Schneider, Tapio Yanamandra-Fisher, Padma A. de Pater, Imke Edwards, Michelle Geballe, Thomas R. Hammel, Heidi B. Fujiyoshi, Takuya Encrenaz, Therese Pantin, Eric Mousis, Olivier Fuse, Tetsuharu 2012-02 https://authors.library.caltech.edu/32974/ https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478 unknown Elsevier Orton, Glenn S. and Fletcher, Leigh N. and Liu, Junjun and Schneider, Tapio and Yanamandra-Fisher, Padma A. and de Pater, Imke and Edwards, Michelle and Geballe, Thomas R. and Hammel, Heidi B. and Fujiyoshi, Takuya and Encrenaz, Therese and Pantin, Eric and Mousis, Olivier and Fuse, Tetsuharu (2012) Recovery and characterization of Neptune’s near-polar stratospheric hot spot. Planetary and Space Science, 61 (1). pp. 161-167. ISSN 0032-0633. doi:10.1016/j.pss.2011.06.013. https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478 <https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478> Article PeerReviewed 2012 ftcaltechauth https://doi.org/10.1016/j.pss.2011.06.013 2021-11-11T18:50:34Z Images of Neptune obtained in 2006 at ESO's Very Large Telescope (Orton et al., 2007, Astronomy & Astrophysics 473, L5) revealed a near-polar hot spot near 70°S latitude that was detectable in filters sampling both stratospheric methane (7 μm) and ethane (∼12 μm) emission. Such a feature was not present in 2003 Keck and 2005 Gemini North observations, which showed only a general warming trend toward Neptune's pole that was longitudinally homogeneous. Because of the paucity of longitudinal sampling in the 2003, 2005 and 2006 images, it was not clear whether the failure to see this phenomenon in 2003 and 2005 was simply the result of insufficient longitudinal sampling or whether the phenomenon was truly variable in time. To unravel these two possibilities, we made follow-up observations on large telescopes that were capable of resolving Neptune at thermal-infrared wavelengths: Gemini South in 2007 and 2010 using the T-ReCS instrument, Subaru in 2008 using the COMICS instrument and VLT in 2008 and 2009 using the VISIR instrument. Two serendipitous T-ReCS images of Neptune were also obtained in 2007 using a broad N-band (8–14 μm) filter, whose radiance is dominated by stratospheric emission from both methane and ethane. The feature was recovered (i) in 2007 with T-ReCS in the broad N-band image and (ii) in 2008 with COMICS in a 12.5-μm image. However, T-ReCS observations in 2010 that covered up to 250° of longitude did not show evidence of an off-polar hot spot. Although we have not definitively ruled out the possibility that various observers have simply missed a semi-permanent feature, it seems statistically very unlikely to be the case. With only 3 sightings in 13 independent observing epochs, it is likely that the phenomenon is ephemeral in time. A possible origin for the phenomenon is a large planetary wave that is dynamically confined to the high-latitude regions characterized by prograde zonal winds. It may be episodically excited by dynamical activity deeper in the atmosphere. This must be coupled with mixing near the poles that destroys or at least substantially attenuates the hot spot over the south pole that leads to an appearance of the typical polar stratospheric hot spot being offset in latitude. Article in Journal/Newspaper South pole Caltech Authors (California Institute of Technology) Gemini ENVELOPE(-62.500,-62.500,-66.133,-66.133) South Pole Planetary and Space Science 61 1 161 167 |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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description |
Images of Neptune obtained in 2006 at ESO's Very Large Telescope (Orton et al., 2007, Astronomy & Astrophysics 473, L5) revealed a near-polar hot spot near 70°S latitude that was detectable in filters sampling both stratospheric methane (7 μm) and ethane (∼12 μm) emission. Such a feature was not present in 2003 Keck and 2005 Gemini North observations, which showed only a general warming trend toward Neptune's pole that was longitudinally homogeneous. Because of the paucity of longitudinal sampling in the 2003, 2005 and 2006 images, it was not clear whether the failure to see this phenomenon in 2003 and 2005 was simply the result of insufficient longitudinal sampling or whether the phenomenon was truly variable in time. To unravel these two possibilities, we made follow-up observations on large telescopes that were capable of resolving Neptune at thermal-infrared wavelengths: Gemini South in 2007 and 2010 using the T-ReCS instrument, Subaru in 2008 using the COMICS instrument and VLT in 2008 and 2009 using the VISIR instrument. Two serendipitous T-ReCS images of Neptune were also obtained in 2007 using a broad N-band (8–14 μm) filter, whose radiance is dominated by stratospheric emission from both methane and ethane. The feature was recovered (i) in 2007 with T-ReCS in the broad N-band image and (ii) in 2008 with COMICS in a 12.5-μm image. However, T-ReCS observations in 2010 that covered up to 250° of longitude did not show evidence of an off-polar hot spot. Although we have not definitively ruled out the possibility that various observers have simply missed a semi-permanent feature, it seems statistically very unlikely to be the case. With only 3 sightings in 13 independent observing epochs, it is likely that the phenomenon is ephemeral in time. A possible origin for the phenomenon is a large planetary wave that is dynamically confined to the high-latitude regions characterized by prograde zonal winds. It may be episodically excited by dynamical activity deeper in the atmosphere. This must be coupled with mixing near the poles that destroys or at least substantially attenuates the hot spot over the south pole that leads to an appearance of the typical polar stratospheric hot spot being offset in latitude. |
format |
Article in Journal/Newspaper |
author |
Orton, Glenn S. Fletcher, Leigh N. Liu, Junjun Schneider, Tapio Yanamandra-Fisher, Padma A. de Pater, Imke Edwards, Michelle Geballe, Thomas R. Hammel, Heidi B. Fujiyoshi, Takuya Encrenaz, Therese Pantin, Eric Mousis, Olivier Fuse, Tetsuharu |
spellingShingle |
Orton, Glenn S. Fletcher, Leigh N. Liu, Junjun Schneider, Tapio Yanamandra-Fisher, Padma A. de Pater, Imke Edwards, Michelle Geballe, Thomas R. Hammel, Heidi B. Fujiyoshi, Takuya Encrenaz, Therese Pantin, Eric Mousis, Olivier Fuse, Tetsuharu Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
author_facet |
Orton, Glenn S. Fletcher, Leigh N. Liu, Junjun Schneider, Tapio Yanamandra-Fisher, Padma A. de Pater, Imke Edwards, Michelle Geballe, Thomas R. Hammel, Heidi B. Fujiyoshi, Takuya Encrenaz, Therese Pantin, Eric Mousis, Olivier Fuse, Tetsuharu |
author_sort |
Orton, Glenn S. |
title |
Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
title_short |
Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
title_full |
Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
title_fullStr |
Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
title_full_unstemmed |
Recovery and characterization of Neptune’s near-polar stratospheric hot spot |
title_sort |
recovery and characterization of neptune’s near-polar stratospheric hot spot |
publisher |
Elsevier |
publishDate |
2012 |
url |
https://authors.library.caltech.edu/32974/ https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478 |
long_lat |
ENVELOPE(-62.500,-62.500,-66.133,-66.133) |
geographic |
Gemini South Pole |
geographic_facet |
Gemini South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
Orton, Glenn S. and Fletcher, Leigh N. and Liu, Junjun and Schneider, Tapio and Yanamandra-Fisher, Padma A. and de Pater, Imke and Edwards, Michelle and Geballe, Thomas R. and Hammel, Heidi B. and Fujiyoshi, Takuya and Encrenaz, Therese and Pantin, Eric and Mousis, Olivier and Fuse, Tetsuharu (2012) Recovery and characterization of Neptune’s near-polar stratospheric hot spot. Planetary and Space Science, 61 (1). pp. 161-167. ISSN 0032-0633. doi:10.1016/j.pss.2011.06.013. https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478 <https://resolver.caltech.edu/CaltechAUTHORS:20120807-101117478> |
op_doi |
https://doi.org/10.1016/j.pss.2011.06.013 |
container_title |
Planetary and Space Science |
container_volume |
61 |
container_issue |
1 |
container_start_page |
161 |
op_container_end_page |
167 |
_version_ |
1766202950062964736 |