Article (Scientific journals)
Pluto's atmosphere from stellar occultations in 2012 and 2013
Dias-Oliveira, A.; Sicardy, B.; Lellouch, Emmanuel et al.
2015In Astrophysical Journal, 1506, p. 8173
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Keywords :
Astrophysics - Earth and Planetary Astrophysics
Abstract :
[en] We analyze two multi-chord stellar occultations by Pluto observed on July 18th, 2012 and May 4th, 2013, and monitored respectively from five and six sites. They provide a total of fifteen light-curves, twelve of them being used for a simultaneous fit that uses a unique temperature profile, assuming a clear (no-haze) and pure N_2 atmosphere, but allowing for a possible pressure variation between the two dates. We find a solution that fits satisfactorily (i.e. within the noise level) all the twelve light-curves, providing atmospheric constraints between ~1,190 km (pressure ~ 11 µbar) and ~ 1,450 km (pressure ~0.1 µbar) from Pluto's center. Our main results are: (1) the best-fitting temperature profile shows a stratosphere with strong positive gradient between 1,190 km (at 36 K, 11 µbar) and r = 1,215 km (6.0 µbar), where a temperature maximum of 110 K is reached; above it is a mesosphere with negative thermal gradient of -0.2 K/km up to ~ 1,390 km (0.25 µbar), where, the mesosphere connects itself to a more isothermal upper branch around 81 K; (2) the pressure shows a small (6%) but significant increase (6σ level) between the two dates; (3) without a troposphere, Pluto's radius is found to be ${R}_{{\rm{P}}}=1190\;\pm $ 5 km. Allowing for a troposphere, RP is constrained to lie between 1168 and 1195 km; and (4) the currently measured CO abundance is too small to explain the mesospheric negative thermal gradient. Cooling by HCN is possible, but only if this species is largely saturated. Alternative explanations like zonal winds or vertical compositional variations of the atmosphere are unable to explain the observed mesospheric negative thermal gradient.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Dias-Oliveira, A.
Sicardy, B.
Lellouch, Emmanuel
Vieira-Martins, R.
Assafin, M.
Camargo, J. I. B.
Braga-Ribas, F.
Gomes-Júnior, A. R.
Benedetti-Rossi, G.
Colas, F.
Decock, A.
Doressoundiram, A.
Dumas, C.
Emilio, M.
Fabrega Polleri, J.
Gil-Hutton, R.
Gillon, Michaël  ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Girard, J.
Hau, G.
Ivanov, V. D.
Jehin, Emmanuel  ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Lecacheux, J.
Leiva, R.
Lopez-Sisterna, C.
Mancini, L.
Maury, A.
Meza, E.
Morales, N.
Nagy, L.
Opitom, Cyrielle ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Ortiz, J. L.
Pollock, J.
Roques, F.
Snodgrass, C.
Soulier, J. F.
Thirouin, A.
Vanzi, L.
Widemann, T.
Reichart, D. E.
LaCluyze, A. P.
Haislip, J. B.
Ivarsen, K. M.
Dominik, M.
Jørgensen, U.
Skottfelt, J.
More authors (35 more) Less
Language :
English
Title :
Pluto's atmosphere from stellar occultations in 2012 and 2013
Publication date :
01 June 2015
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
IOP Publishing
Volume :
1506
Pages :
8173
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
41 pages, 13 figures, 4 tables. Submitted to ApJ
Available on ORBi :
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