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Limits on Dione's Activity Using Cassini/CIRS Data
Author(s) -
Howett Carly J. A.,
Spencer John R.,
Hurford Terry,
Verbiscer Anne,
Segura Marcia
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl078161
Subject(s) - middle latitudes , latitude , atmospheric sciences , low latitude , hot spot (computer programming) , environmental science , surface (topology) , climatology , geology , astrophysics , physics , geodesy , geometry , mathematics , computer science , operating system
We use nighttime Cassini Composite Infrared Spectrometer (CIRS) data to look for discrete regions of elevated nighttime temperatures indicative of endogenic activity on Dione's surface. This is achieved by producing low latitude and midlatitude (less than 60°) maps of Dione's nighttime surface temperature, derived from 10 to 1,100‐cm −1 CIRS data. The surface temperatures observed do not show evidence of any small discrete regions of elevated nighttime temperatures and are comparable to temperatures predicted by a passive thermophysical model of Dione's surface. Thus, we conclude that no evidence for activity exists on Dione at midlatitude to low latitude. Using the derived surface temperature maps, we set upper limits for the temperature at which a 50‐, 100‐, or 200‐km 2 hot spot would remain undetected by this study. We find the mean temperature of such a hot spot would be 117.1 ± 47.2 K (−249 F), 104.8 ± 27.7 K (−272 F), and 95.4 ± 19.5 K (−288 F) for a 50‐, 100‐, and 200‐km 2 hot spot, respectively, corresponding to endogenic emission of 1.07, 0.68, and 0.47 GW.