Lower Surface Temperature at Bright Ephemeral Feature Site on Titan's North Pole

Abstract

We report a temperature difference in one of the regions on Titan that is, documented as a bright ephemeral feature (BEF). Spectra were recorded by Cassini's Composite Infrared Spectrometer. BEFs are 5 µm bright areas that appear, disappear, and shift from flyby to flyby at Titan's North Pole observed in Visual and Infrared Mapping Spectrometer (VIMS) data. They are inferred to be broad specular reflections caused by a smooth surface on Titan or a near surface fog—both of which indicate that the atmosphere interacted with the surface. We used 24 spectra for "on the BEF" and 51 spectra for "off the BEF" region to determine the temperature difference during the T121 flyby (July 25, 2016). At the 410-560 cm⁻¹ window where surface emissions are perceptible we see a decrease in temperature by 1.2 ± 0.2 K. This decrease in temperature might indicate precipitative cooling after a fresh rainfall on Titan's land/sea surface.