| Title: |
Titan's prolific propane: The Cassini CIRS perspective |
| Authors: |
Nixon, Conor A.; Jennings, Donald E.; Flaud, Jean-Marie; Bézard, Bruno; Teanby, Nicholas A.; Irwin, Patrick G. J.; Ansty, Todd M.; Coustenis, Athéna; Vinatier, Sandrine; Flasar, Michael |
| Contributors: |
University of Maryland; Solar System Exploration Division, Planetary Systems Laboratory - Code 693, NASA Goddard Space Flight Center, Greenbelt; Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)); Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité); Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA); Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS); Pôle Planétologie du LESIA; Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA); Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité); Department of Atmospheric, Oceanic and Planetary Physics Oxford (AOPP); University of Oxford; Department of Astronomy, Cornell University |
| Source: |
ISSN: 0032-0633 ; Planetary and Space Science ; https://hal.science/hal-03742407 ; Planetary and Space Science, 2009, 57, pp.1573-1585. ⟨10.1016/j.pss.2009.06.021⟩. |
| Publisher Information: |
HAL CCSD; Elsevier |
| Publication Year: |
2009 |
| Subject Terms: |
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; envir; geo |
| Description: |
International audience ; Although propane gas ( C 3 H 8 ) was first detected in the stratosphere of Titan by the Voyager IRIS infrared spectrometer in 1980, obtaining an accurate measurement of its abundance has proved difficult. All existing measurements have been made by modeling the nu 26 band at 748cm -1 : however, different analyzes over time have yielded quite different results, and it also suffers from confusion with the strong nearby nu 5 band of acetylene. In this paper we select large spectral averages of data from the Cassini Composite Infrared Spectrometer (CIRS) obtained in limb-viewing mode at low latitudes (30 oS-30 oN), greatly increasing the path length and hence signal-to-noise ratio for optically thin trace species such as propane. By modeling and subtracting the emissions of other gas species, we demonstrate that at least six infrared bands of propane are detected by CIRS, including two not previously identified in Titan spectra. Using a new linelist for the range 1300-1400 cm -1 , along with an existing GEISA list, we retrieve propane abundances from two bands at 748 and 1376 cm -1 . At 748 cm -1 we retrieve 4.2±0.5×10 -7 ( 1-sigma error) at 2 mbar, in good agreement with previous studies, although lack of hotbands in the present spectral atlas remains a problem. We also determine 5.7±0.8×10 -7 at 2 mbar from the 1376 cm -1 band - a value that is probably affected by systematic errors including continuum gradients due to haze and also an imperfect model of the nu 6 band of ethane. This study clearly shows for the first time the ubiquity of propane's emission bands across the thermal infrared spectrum of Titan, and points to an urgent need for further laboratory spectroscopy work, both to provide the line positions and intensities needed to model these bands, and also to further characterize haze spectral opacity. The present lack of accurate modeling capability for propane is an impediment not only for the measurement of propane itself, but also for the search for the emissions of new . |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://hal.science/hal-03742407 |
| Availability: |
https://hal.science/hal-03742407 |
| Rights: |
undefined |
| Accession Number: |
edsbas.4B785EC8 |
| Database: |
BASE |