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Pluto's atmosphere from the 2015 June 29 ground-based stellar occultation at the time of the new horizons flyby

Citation

Sicardy, B and Talbot, J and Meza, E and Camargo, JIB and Desmars, J and Gault, D and Herald, D and Kerr, S and Pavlov, H and Braga-Ribas, F and Assafin, M and Benedetti-Rossi, G and Dias-Oliveira, A and Gomes-Junior, AR and Vieira-Martins, R and Berard, D and Kervella, P and Lecacheux, J and Lellouch, E and Beisker, W and Dunham, D and Jelinek, M and Duffard, R and Ortiz, JL and Castro-Tirado, AJ and Cunniffe, R and Querel, R and Yock, PC and Cole, AA and Giles, AB and Hill, KM and Beaulieu, JP and Harnisch, M and Jansen, R and Pennell, A and Todd, S and Allen, WH and Graham, PB and Loader, B and McKay, G and Milner, J and Parker, S and Barry, MA and Bradshaw, J and Broughton, J and Davis, L and Devillepoix, H and Drummond, J and Field, L and Forbes, M and Giles, D and Glassey, R and Groom, R and Hooper, D and Horvat, R and Hudson, G and Idaczyk, R and Jenke, D and Lade, B and Newman, J and Nosworthy, P and Purcell, P and Skilton, PF and Streamer, M and Unwin, M and Watanabe, H and White, GL and Watson, D, Pluto's atmosphere from the 2015 June 29 ground-based stellar occultation at the time of the new horizons flyby, Astrophysical Journal Letters, 819, (2) Article L38. ISSN 2041-8205 (2016) [Refereed Article]


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© 2016. The American Astronomical Society. All rights reserved.

DOI: doi:10.3847/2041-8205/819/2/L38

Abstract

We present results from a multi-chord Pluto stellar occultation observed on 2015 June 29 from New Zealand and Australia. This occurred only two weeks before the NASA New Horizons flyby of the Pluto system and serves as a useful comparison between ground-based and space results. We find that Pluto's atmosphere is still expanding, with a significant pressure increase of 5 ± 2% since 2013 and a factor of almost three since 1988. This trend rules out, as of today, an atmospheric collapse associated with Pluto's recession from the Sun. A central flash, a rare occurrence, was observed from several sites in New Zealand. The flash shape and amplitude are compatible with a spherical and transparent atmospheric layer of roughly 3 km in thickness whose base lies at about 4 km above Pluto's surface, and where an average thermal gradient of about 5 K km−1 prevails. We discuss the possibility that small departures between the observed and modeled flash are caused by local topographic features (mountains) along Pluto's limb that block the stellar light. Finally, using two possible temperature profiles, and extrapolating our pressure profile from our deepest accessible level down to the surface, we obtain a possible range of 11.9–13.7 μbar for the surface pressure.

Item Details

Item Type:Refereed Article
Keywords:Kuiper belt objects: individual (Pluto), occultations, planets and satellites: atmospheres, techniques: photometric
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Planetary Science (excl. Extraterrestrial Geology)
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Cole, AA (Associate Professor Andrew Cole)
Author:Giles, AB (Dr Barry Giles)
Author:Hill, KM (Dr Kym Hill)
ID Code:107646
Year Published:2016
Funding Support:Australian Research Council (LE110100055)
Web of Science® Times Cited:11
Deposited By:Mathematics and Physics
Deposited On:2016-03-21
Last Modified:2017-11-06
Downloads:78 View Download Statistics

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