Detection of Propadiene on Titan

dc.contributor.authorLombardo, Nicholas A.
dc.contributor.authorNixon, Conor A.
dc.contributor.authorGreathouse, Thomas K.
dc.contributor.authorBézard, Bruno
dc.contributor.authorJolly, Antoine
dc.contributor.authorVinatier, Sandrine
dc.contributor.authorTeanby, Nicholas A.
dc.contributor.authorRichter, Matthew J.
dc.contributor.authorIrwin, Patrick J. G.
dc.contributor.authorCoustenis, Athena
dc.contributor.authorFlasar, F. Michael
dc.date.accessioned2019-11-22T17:52:48Z
dc.date.available2019-11-22T17:52:48Z
dc.date.issued2019-08-20
dc.description.abstractThe atmosphere of Titan, the largest moon of Saturn, is rich in organic molecules, and it has been suggested that the moon may serve as an analog for the pre-biotic Earth due to its highly reducing chemistry and existence of global hazes. Photochemical models of Titan have predicted the presence of propadiene (historically referred to as allene), CH₂CCH₂, an isomer of the well-measured propyne (also called methylacetylene) CH₃CCH, but its detection has remained elusive due to insufficient spectroscopic knowledge of the molecule. This has recently been remedied with an updated spectral line list. Here we present the first unambiguous detection of the molecule in any astronomical object, observed with the Texas Echelle Cross Echelle Spectrograph on the NASA Infrared Telescope Facility in 2017 July. We model its emission line near 12 μm and measure a volume mixing ratio of (6.9 ± 0.8) × 10−¹⁰ at 175 km, assuming a vertically increasing abundance profile as predicted in photochemical models. Cassini measurements of propyne made during 2017 April indicate that the abundance ratio of propyne to propadiene is 8.2 ± 1.1 at the same altitude. This initial measurement of the molecule in Titan’s stratosphere paves the way toward constraining the amount of atomic hydrogen available on Titan, as well as future mapping of propadiene on Titan from 8 m and larger ground-based observatories, and future detection on other planetary bodies.en_US
dc.description.sponsorshipN.A.L., C.A.N., and F.M.F. were supported by the NASA Cassini Project for the research work reported in this Letter. P.G.J.I. and N.A.T. were funded by the UK Science and Technology Facilities Council. N.A.L. was supported by NASA through the CRESST II cooperative agreement CA 80GSFC17M0002. C.A.N. received additional funding through NASA’s Astrobiology Institute grant “Habitability of Hydrocarbons Worlds: Titan and Beyond,” and NASA’s Solar System Observations Program. N.A.L. and T.K.G. were Visiting Astronomers at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration.en_US
dc.description.urihttps://iopscience.iop.org/article/10.3847/2041-8213/ab3860en_US
dc.format.extent6 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2ss4o-i9m8
dc.identifier.citationLombardo, Nicholas A.; Nixon, Conor A.; Greathouse, Thomas K.; Bézard, Bruno; Jolly, Antoine; Vinatier, Sandrine; Teanby, Nicholas A.; Richter, Matthew J.; Irwin, Patrick J. G.; Coustenis, Athena; Flasar, F. Michael; Detection of Propadiene on Titan; The Astrophysical Journal Letters, Volume 881, Number 2(2019); https://iopscience.iop.org/article/10.3847/2041-8213/ab3860;en_US
dc.identifier.urihttp://hdl.handle.net/11603/16513
dc.language.isoen_USen_US
dc.publisherThe American Astronomical Societyen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Center for Space Sciences and Technology
dc.relation.ispartofUMBC Faculty Collection
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rights©2019. The American Astronomical Society. All rights reserved.
dc.subjectsaturnian satellitesen_US
dc.subjectplanetary atmospheresen_US
dc.subjectpre-biotic astrochemistryen_US
dc.subjectplanetary scienceen_US
dc.titleDetection of Propadiene on Titanen_US
dc.typeTexten_US

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