SYMPA, a dedicated instrument for Jovian seismology

Abstract

Aims. The detection and measurement of acoustic modes on the giant planets of the solar system is of great interest for the study of the internal structure and evolution of the giant planets, as well as the study of the solar system formation. Such observations require a dedicated instrument and observing procedure. Methods. We describe the principle and the performance of an instrument dedicated to seismology of giant planets. In this first paper, we describe the principle and the optical scheme, and derive the theoretical performances. As for the Sun, it is possible to measure modes with spatial resolution, but a larger collecting area is necessary. As for asteroseismology in general, continuity in the observation is also required. Results. From results obtained at the laboratory, we derive the actual performance of the instrument and estimate its capabilities in network observations. Conclusions. We demonstrate that the proposed instrument and strategy is adapted for the seismology of giant planets. In a second paper, we will present the first data set obtained with it, explain the data reduction procedure, and present preliminary results.

Detection of Jovian seismic waves: a new probe of its interior structure

“…The inhomogeneities in both the photometric and dynamic structure could indeed affect the measured signal. The effect of quasi-periodic albedo features and its possible contamination of Doppler measurements was studied in Lederer et al (1995) source of spurious velocity signals in the case of spatially unresolved Doppler measurements as in Schmider et al (1991) and Mosser et al (1993). Most of the detected frequencies were found below 1000 μHz, but that might be a consequence of the limited spatial resolution of their dataset.…”

“…As we simultaneously recorded the photometric images, it is possible to compute the power spectrum of the photometric time series associated with our measurements. For each exposure, the sum of the four outputs of the instrument is an image of Jupiter with the fringe pattern suppressed (Schmider et al 2007). We multiplied each image for the whole run with the pair of masks l, m = 1, 0 and l, m = 1, 1, eliminating the outer 25% of Jupiter's diameter, to obtain two new times series.…”

Seismology of Giant Planets: General Overview and Results from theKeplerK2 Observations of Neptune

“…There have been several attempts to detect Jovian oscillations using infrared photometry [18], Doppler spectrometry [19][20][21], and careful searches for excitation of acoustic waves due to the impact of the Shoemaker-Levy 9 comet [22,23]. In most of these campaigns, the signal-to-noise (SNR) ratio was too low or instrumental artifacts were present that inhibited any positive detection.…”

“…Jovian seismology had to wait until 2011 to get the first strong evidence of the detection of oscillations using the SYMPA instrument, an imaging spectrometer based on a Mach-Zehnder interferometer at fixed optical path difference [24]. This instrument was designed to overcome some of the earlier limitations by imaging the full planetary disk, similar to solar helioseismic instruments like GONG [25], MDI/SOHO [26], and HMI/SDO [27].…”

Physics of Substellar Objects Interiors, Atmospheres, Evolution

“…Such a discovery would lead to great leaps in our knowledge of the interior of these planets, as can be seen from the level of accuracy reached by solar interior models since the discovery of its oscillations. Observations aimed at detecting modes of Jupiter have shown promising results (Schmider et al 1991), but have thus far been limited by instrumental and windowing effects. A recent work by Mosser et al (2000) puts an upper limit to the amplitude of the modes at 0.6 m s −1 , and shows an increased energy of the Fourier spectrum in the expected range of frequencies.…”