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An unidentified emission in Titan's upper atmosphere
Author(s) -
Dinelli B. M.,
LópezPuertas M.,
Adriani A.,
Moriconi M. L.,
Funke B.,
GarcíaComas M.,
D'Aversa E.
Publication year - 2013
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 - 10.1002/grl.50332
Subject(s) - titan (rocket family) , methane , atmosphere (unit) , astrobiology , atmosphere of titan , infrared , physics , daytime , astrophysics , atmospheric sciences , geology , environmental science , astronomy , meteorology , chemistry , organic chemistry
We have analyzed limb daytime observations of Titan's upper atmosphere at 3.3 μ m, acquired by the visual‐infrared mapping spectrometer (VIMS) on Cassini. They were previously studied by García‐Comas et al. (2011) to derive CH 4 densities. Here, we report an unidentified emission peaking around 3.28 μ m, hidden under the methane R branch. This emission is very strong, with intensity comparable to the CH 4 bands located in the same spectral region. It presents a maximum at about 950 km and extends from 600 km up to 1250 km. It is definitely pumped by solar radiation since it vanishes at night. Our analysis shows that neither methane nor the major hydrocarbon compounds already discovered in Titan's upper atmosphere are responsible for it. We have discarded many other potential candidates and suggest that the unidentified emission might be caused by aromatic compounds.