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Neptune long-lived atmospheric features in 2013–2015 from small (28-cm) to large (10-m) telescopes

Hueso, R. and de Pater, I. and de Kleer, K. and Riddle, R. (2017) Neptune long-lived atmospheric features in 2013–2015 from small (28-cm) to large (10-m) telescopes. Icarus, 295 . pp. 89-109. ISSN 0019-1035.

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Since 2013, observations of Neptune with small telescopes (28–50 cm) have resulted in several detections of long-lived bright atmospheric features that have also been observed by large telescopes such as Keck II or Hubble. The combination of both types of images allows the study of the long-term evolution of major cloud systems in the planet. In 2013 and 2014 two bright features were present on the planet at southern mid-latitudes. These may have merged in late 2014, possibly leading to the formation of a single bright feature observed during 2015 at the same latitude. This cloud system was first observed in January 2015 and nearly continuously from July to December 2015 in observations with telescopes in the 2-10-m class and in images from amateur astronomers. These images show the bright spot as a compact feature at −40.1 ± 1.6° planetographic latitude well resolved from a nearby bright zonal band that extended from −42° to −20°. The size of this system depends on wavelength and varies from a longitudinal extension of 8000 ± 900 km and latitudinal extension of 6500 ± 900 km in Keck II images in H and Ks bands to 5100 ± 1400 km in longitude and 4500 ± 1400 km in latitude in HST images in 657 nm. Over July to September 2015 the structure drifted westward in longitude at a rate of 24.48 ± 0.03°/day or −94 ± 3 m/s. This is about 30 m/s slower than the zonal winds measured at the time of the Voyager 2 flyby. Tracking its motion from July to November 2015 suggests a longitudinal oscillation of 16° in amplitude with a 90-day period, typical of dark spots on Neptune and similar to the Great Red Spot oscillation in Jupiter. The limited time covered by high-resolution observations only covers one full oscillation and other interpretations of the changing motions could be possible. HST images in September 2015 show the presence of a dark spot at short wavelengths located in the southern flank (planetographic latitude −47.0°) of the bright compact cloud observed throughout 2015. The drift rate of the bright cloud and dark spot translates to a zonal speed of −87.0 ± 2.0 m/s, which matches the Voyager 2 zonal speeds at the latitude of the dark spot. Identification of a few other features in 2015 enabled the extraction of some limited wind information over this period. This work demonstrates the need of frequently monitoring Neptune to understand its atmospheric dynamics and shows excellent opportunities for professional and amateur collaborations.

Item Type:Article
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URLURL TypeDescription
Hueso, R.0000-0003-0169-123X
de Pater, I.0000-0002-4278-3168
de Kleer, K.0000-0002-9068-3428
Riddle, R.0000-0002-0387-370X
Additional Information:© 2017 Elsevier Inc. Received 8 November 2016, Revised 15 May 2017, Accepted 5 June 2017, Available online 7 June 2017. We thank two anonymous referees from their constructive comments that improved the contents of this paper. We are very grateful to Grischa Hahn for his update on the WinJupos software incorporating the ephemeris of Triton that allowed the measurement of amateur images of Neptune. We are also grateful to many amateur observers that observed Neptune intensively over 2013 to 2015 providing data for this research. We are also thankful to P. Irwin for giving permission to use his VLT/SINFONI observations of Neptune. Observations for this research were obtained at the following observatories: Pic du Midi in France, Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, Spain, the Lick Observatory and Palomar Observatory in California and the W.M. Keck Observatory in Hawaii. The Centro Astronómico Hispano Alemán (CAHA) at Calar Alto is operated jointly by the Max Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). The Robo-AO system was developed by collaborating partner institutions, the California Institute of Technology and the Inter-University Centre for Astronomy and Astrophysics, and with the support of the National Science Foundation under grant Nos. AST-0906060, AST-0960343, AST-0908575, AST-1207891 and AST-1615004, the Mt. Cuba Astronomical Foundation, and by a gift from Samuel Oschin. Research at Lick Observatory is partially supported by a generous gift from Google. The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Additional observations were acquired by the Hubble Space Telescope (Programs GO 13937, 14044). Portions of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. C.B. acknowledges support from the Alfred P. Sloan Foundation. This work was supported by the Spanish MINECO project AYA2015-65041-P (MINECO/FEDER, UE), Grupos Gobierno Vasco IT-765-13, UPV/EHU UFI11/55 and ‘Infraestructura’ grants from Gobierno Vasco and UPV/EHU.
Group:Astronomy Department
Funding AgencyGrant Number
Mt. Cuba Astronomical FoundationUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Department of Energy (DOE)DE-AC52-07NA27344
Alfred P. Sloan FoundationUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)AYA2015-65041-P
Grupos Gobierno VascoIT-765-13
University of the Basque CountryUPV/EHU UFI11/55
Record Number:CaltechAUTHORS:20190611-141527333
Persistent URL:
Official Citation:Luszcz-Cook, G.S. Orton, H.B. Hammel, J.M. Gómez-Forrellad, I. Ordonez-Etxeberria, L. Sromovsky, P. Fry, F. Colas, J.F. Rojas, S. Pérez-Hoyos, P. Gorczynski, J. Guarro, W. Kivits, P. Miles, D. Millika, P. Nicholas, J. Sussenbach, A. Wesley, K. Sayanagi, S.M. Ammons, E.L. Gates, D. Gavel, E. Victor Garcia, N.M. Law, I. Mendikoa, R. Riddle, Neptune long-lived atmospheric features in 2013–2015 from small (28-cm) to large (10-m) telescopes, Icarus, Volume 295, 2017, Pages 89-109, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96300
Deposited By: Tony Diaz
Deposited On:11 Jun 2019 23:11
Last Modified:20 Apr 2020 08:47

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