31st Annual Meeting of the DPS, October 1999
Session 53. Outer Planet Physics I Posters
Poster Group II, Thursday-Friday, October 14, 1999, Kursaal Center

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[53.09] The detectability of global oscillations on Jupiter and Saturn with the Magneto-Optical Filter

M. Dolci, A. Cacciani (Univ. La Sapienza di Roma)

The Magneto-Optical Filter (MOF) transmits the light in two very narrow (40 mÅ) bandpasses (B and R) located on the opposite wings of a spectral line. With a suitable elaboration of the transmitted channels (\cal R=(B-R)/(B+R) or \cal S=(B+R)/continuum) it is possible to get direct information about the velocity fields present on the surface of the observed object. Jovian sesimological observations, carried out in the past with this technique, found "global oscillations" with amplitudes around 8 m s-1 [3]; these "modes", however, could also be due to albedo fluctuations on Jupiter's surface [2]. Recent observations have detected no oscillations and given strong support to the albedo hypothesis [1]. The various experimental results can be reconciled if the sensitivities of \cal R and \cal S to the different oscillation or albedo "modes" is carefully computed. These sensitivities change with the mode degree (\ell,m) and with the observation date tobs. When applied to the two above-mentioned experiments, they agree very well with the observed results.

The authors thank the Ministero della Pubblica Istruzione and the Osservatorio Astronomico "V.Cerulli" di Teramo for financial support.


{ \smallskip [1] Cacciani A., Moretti P. F., Dolci M., D'Alessio F., Giuliani C., Micolucci E., Di Cianno A., 1999: Search for global oscillations on Jupiter with a double-cell Sodium Magneto-Optical Filter, submitted to Astron. Astrophys. \smallskip [2] Lederer S. M., Marley M. S., Mosser B., Maillard J. P., Chanover N. J., Beebe R. F., 1995: Albedo Features and Jovian Seismology, Icarus, 114, 269 \smallskip [3] Schmider F. X., Mosser B., Fossat E., 1991: Possible detection of Jovian global oscillations, Astron. Astrophys., 248, 281}

The author(s) of this abstract have provided an email address for comments about the abstract: alessandro.cacciani@roma1.infn.it

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