- Names
-
- Lora Jovanović
- Thomas Gautier
- Véronique Vuitton
- Cédric Wolters
- Jérémy Bourgalais
- Arnaud Buch
- Françcois-Régis Orthous-Daunay
- Ludovic Vettier
- Laurène Flandinet
- Nathalie Carrasco
- Title
- Chemical composition of Pluto aerosol analogues
- Abstract
- Photochemical aerosols were observed in Pluto atmosphere during the New Horizons flyby on July 14$^{th}$, 2015, as several thin haze layers extending at $\gt$350 km of altitude. This flyby has raised numerous questions on the aerosols formation processes and their impact on Pluto radiative transfer and climate. In order to gain a better understanding, we synthesized Pluto aerosol analogues in a room-temperature dusty plasma experiment and inferred their chemical composition from infrared spectroscopy, elemental composition analysis and very high- resolution mass spectrometry (ESI+/Orbitrap device). Three types of samples were synthesized at 0.9 \ensuremath\pm 0.1 mbar, called P$_{400}$, P$_{600}$ and P$_{CO-free}$. The samples P$_{400}$ and P$_{600}$ were produced from gas mixtures mimicking Pluto atmosphere at around 400 and 600 km of altitude, respectively, in order to determine if CH$_4$ mixing ratio has an influence on the chemical composition of the aerosols. The sample P$_CO-free$ was produced from a gas mixture similar to the one forming the sample P$_{400}$, but without carbon monoxide, in order to identify the impact of CO. \textbackslash\textbackslashOur study shows that the molecules constituting samples P$_{400}$ and P$_{600}$ are very rich in nitrogen atoms (up to 45% in mass of N elements) and, compared to the molecules constituting the P$_{CO-free}$ sample, a significant incorporation of oxygen atoms was detected. Moreover, our results on the variation of CH$_4$ mixing ratio demonstrate that different ratios lead to different reactivity between N$_2$, CH$_4$ and CO. In particular, more nitrogen and oxygen atoms are detected in the bulk composition of the analogues P$_{400}$. Due to the presence of nitrogenated and oxygenated molecules in the analogues of Pluto aerosols, we suggest that these aerosols will have an impact on Pluto radiative transfer, and thus on climate, that will differ from predictions based on the optical constants of Titan aerosol analogues.
- Keywords
- spectroscopy, mid-IR, absorbance spectra, tholins, organic matter, composition, molecular bond, Pluto, aerosols, atmosphere, chemistry, Organic chemistry
- Content
- material-matter, spectral data, planetary sciences
- Document type
- article
- Publication state
- published
- Doi
- 10.1016/j.icarus.2020.113774
- Identifiers
-
- bibcode: 2020Icar..34613774J