Abstract
We present H-band (1.4–1.8 μm) images of Neptune with a spatial resolution of ∼0.06″, taken with the W.M. Keck II telescope using the slit-viewing camera (SCAM) of the NIRSPEC instrument backed with Adaptive Optics. Images with 60-second integration times span 4 hours each on UT 20 and 21 August, 2001 and ∼1 hour on UT 1 September, 2001. These images were used to characterize the overall brightness distribution on Neptune, and to determine rotations periods (which translate into wind speeds) of individual cloud features.
The images show that the spatial brightness distribution of cloud features, in particular the bright bands at mid-southern latitudes and near 30°N, changed considerably between 1989 (Voyager era) and 2001. The brightest features extend latitudinally over several degrees, and despite the different velocities in different latitude bands, these bright features remain coherent. We show that these features are bright in part because of the foreshortening effect near the limb, which suggests that the features may be composed of small bright clouds that happen to line up near the limb.
At certain latitudes (mid-southern and northern latitudes), there is considerable dispersion in relative rotation periods (and hence zonal velocities) of faint and moderately bright features, while there is essentially no velocity dispersion of features at 50°S. While the zonal speeds of the brightest features are consistent with the Voyager-derived zonal-mean wind profile, there are many cloud features that do not appear to move with the flow. The data are further suggestive of oscillations in longitude, with periods > 4 hrs. We suggest that tidal forcing by Triton could play a role in exciting the waves responsible for the velocity variations of the observed period.
Article PDF
Similar content being viewed by others
References
Asay-Davis, X.S., Marcus, P.S., Wong, M.H., de Pater, I.: Icarus 211, 1215 (2011)
Barranco, J.A., Marcus, P.S.: Astrophys. J. 623, 1157–1170 (2005)
Benielli, D., Sommeria, J.: J. Fluid Mech. 374, 117–144 (1998)
Canny, J.: IEEE Trans. Pattern Anal. Mach. Intell. 8, 679 (1986)
Conrath, B., Flasar, F.M., Hanel, R., Kunde, V., Maguire, W., Pearl, J., Pirraglia, J., Samuelson, R., Cruikshank, D., Horn, L.: Science 246, 1454 (1989)
de Pater, I., Gibbard, S.G., Macintosh, B., Roe, H.G., Gavel, D., Max, C.E.: Icarus 160, 359 (2002)
de Pater, I., Gibbard, S.G., Chiang, E., Hammel, H.B., Macintosh, B., Marchis, F., Martin, S., Roe, H.G., Showalter, M.: Icarus 174, 263 (2005)
Dumas, C., Terrile, R.J., Smith, B.A., Schneider, G.: Astrophys. J. 123, 1776 (2002)
Fry, P.M., Sromovsky, L.A.: Bull. Am. Astron. Soc. 36, 1103 (2004)
Garrett, C., Munk, W.: Annu. Rev. Fluid Mech. 11, 339 (1979)
Gibbard, S.G., de Pater, I., Roe, H.G., Martin, S., Macintosh, B.A., Max, C.E.: Icarus 166, 359–374 (2003)
Gill, A.E.: Atmosphere-Ocean Dynamics. International Geophysics Series, vol. 20. Academic Press, San Diego (1982)
Hammel, H.B.: Science 244, 1165–1167 (1989)
Hammel, H.B., Lockwood, G.W.: Icarus 129, 466 (1997)
Herbert, T.: Annu. Rev. Fluid Mech. 29, 245–283 (1997)
Hines, C.O.: Upper Atmosphere in Motion. Geophysical Monograph Series, vol. 18. American Geophysical Union, Washington (1974)
Ingersoll, A.P., Barnet, C.D., Beebe, R.F., Flasar, F.M., Hinson, D.P., Limaye, S.S., Sromovsky, L.A., Suomi, V.E.: Dynamic meteorology of Neptune. In: Cruikshank, D.P., Matthews, M.S. (eds.) Neptune and Triton. Univ. of Arizona Press, Tucson (1995)
Jacobsen, R.A., Owen, W.M.: Astron. J. 128, 1412 (2004)
Johansson, E.K., et al.: Proc. SPIE 4007, 600 (2000) and 20 colleagues
Lighthill, J.: Waves in Fluids. Cambridge University Press, Cambridge (1978)
Limaye, S.S.: NASA Spec. Publ. 494, 311 (1989)
Limaye, S.S., Sromovsky, L.A.: J. Geophys. Res. 96, 18941 (1991)
Luszcz-Cook, S.H., de Pater, I., Adamkovics, M., Hammel, H.B.: Icarus 208, 938 (2010)
Max, C.E., Macintosh, B.A., Gibbard, S.G., Gavel, D.T., Roe, H.G., de Pater, I., Ghez, A.M., Acton, D.S., Lai, O., Stomski, P., Wizinowich, P.L.: Astron. J. 125, 364 (2003)
McLandress, C.: J. Atmos. Sol.-Terr. Phys. 60, 1357 (1998)
Ni, X.J., Xiong, J.G., Wan, W.X., Ning, B.Q., Liu, L.B.: Earth Planets Space 59, 991 (2007)
Roddier, F., Roddier, C., Graves, J.E., Northcott, M.J., Owen, T.: Icarus 136, 168 (1998)
Roe, H.G.: Publ. Astron. Soc. Pac. 114, 450 (2002)
Sanchez-Lavega, A., Hueso, R., Perez-Hoyos, S.: Icarus 187, 510 (2007)
Sato, K., Kumakura, T., Takahashi, M.: J. Atmos. Sci. 56, 1005 (1999)
Smith, B.A., et al.: Science 246, 1422 (1989) and 64 colleagues
Sromovsky, L.A.: Science 254, 684 (1991)
Sromovsky, L.A., Limaye, S.S., Fry, P.M.: Icarus 105, 110 (1993)
Sromovsky, L.A., Fry, P.M., Baines, K.H., Limaye, S.S., Orton, G.S., Dowling, T.E.: Icarus 149, 416 (2001a)
Sromovsky, L.A., Frye, P.M., Dowling, T., Baines, K.H., Limaye, S.S.: Icarus 149, 459 (2001b)
Sromovsky, L.A., Frye, P.M., Dowling, T., Baines, K.H., Limaye, S.S.: Icarus 150, 244 (2001c)
Sromovsky, L.A., Frye, P.M., Baines, K.H.: Icarus 156, 16 (2002)
Sromovsky, L.A., Fry, P.M., Hammel, H.B., Ahue, A.W., de Pater, I., Rages, K.A., Showalter, M.R., van Dam, M.: Icarus 203, 265–286 (2009)
Stratman, P.W., Showman, A.P., Dowling, T.E., Sromovsky, L.A.: Icarus 151, 275 (2001)
van Dam, M.A., Le Mignant, D., Macintosh, B.A.: Performance of the Keck Observatory adaptive optics system. Appl. Opt. 43, 5458–5467 (2004)
Wizinowich, P., et al.: Publ. Astron. Soc. Pac. 112, 315 (2000a) and 17 colleagues
Wizinowich, P.L., Acton, D.S., Lai, O., Gathright, J., Lupton, W., Stomski, P.J.: Proc. SPIE 4007, 2–13 (2000b)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Martin, S.C., de Pater, I. & Marcus, P. Neptune’s zonal winds from near-IR Keck adaptive optics imaging in August 2001. Astrophys Space Sci 337, 65–78 (2012). https://doi.org/10.1007/s10509-011-0847-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10509-011-0847-y