How Pluto's Ethane Ice Varies Based on Longitude

Longitudinal variability of ethane ice on the surface of Pluto

Authors:

Holler et al

Abstract:

We present the results of an investigation using near-infrared spectra of Pluto taken on 72 separate nights using SpeX/IRTF. These data were obtained between 2001 and 2013 at various sub-observer longitudes. The aim of this work was to confirm the presence of ethane ice and to determine any longitudinal trends on the surface of Pluto. We computed models of the continuum near the 2.405 {\mu}m ethane band using Hapke theory and calculated an equivalent width of the ethane absorption feature for six evenly-spaced longitude bins and a grand average spectrum. Ethane on Pluto was confirmed at the 7.5-{\sigma} level from the grand average spectrum. Additionally, ethane was found to vary longitudinally with the highest abundance present in the N2-rich region and the lowest abundance found in the visibly dark tholin-rich region. We argue for ethane production in the atmosphere and present a theory of volatile transport to explain the observed longitudinal trend.